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Cardiac Emergencies: Assessment

4 Contact Hours including 4 Advanced Pharmacology Hours
This peer reviewed course is applicable for the following professions:
Advanced Registered Nurse Practitioner (ARNP), Certified Nurse Midwife, Certified Nurse Practitioner, Certified Registered Nurse Anesthetist (CRNA), Clinical Nurse Specialist (CNS), Licensed Practical Nurse (LPN), Licensed Vocational Nurses (LVN), Nursing Student, Registered Nurse (RN)
This course will be updated or discontinued on or before Friday, October 27, 2023
Outcomes

≥ 92% of participants will recognize and address acute chest pain.

Objectives

After completing this continuing education course, the participant will be able to:

  1. State life-threatening and non-life-threatening causes of CP.
  2. Differentiate between life-threatening and non-life-threatening causes of CP.
  3. Relate the epidemiology of and risk factors for each life-threatening cause of CP.
  4. Describe the pathogenesis and pathophysiology underlying each cause of life-threatening CP.
  5. Describe the general approach to collecting the patients’ health history when suspecting a life-threatening cause of CP.
  6. State the clinical presentation of each cause of life-threatening CP.
CEUFast Inc. and the course planners for this educational activity do not have any relevant financial relationship(s) to disclose with ineligible companies whose primary business is producing, marketing, selling, re-selling, or distributing healthcare products used by or on patients.

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To earn of certificate of completion you have one of two options:
  1. Take test and pass with a score of at least 80%
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    (NOTE: Some approval agencies and organizations require you to take a test and self reflection is NOT an option.)
Author:    Pamela Downey (MSN, ARNP)

Introduction

Chest pain (CP) accounts for approximately 7.6 million annual visits to emergency departments (EDs) in the United States (U.S.), making CP the second most common complaint (Hollander & Chase, 2021). Patients present with a spectrum of signs and symptoms reflecting the many potential etiologies of CP. Diseases of the heart, aorta, lungs, esophagus, stomach, mediastinum, pleura, and abdominal viscera may all cause chest discomfort.

Clinicians in the ED focus on the immediate recognition and exclusion of life-threatening causes of CP (Hollander & Chase, 2021). Patients with life-threatening etiologies for CP may appear deceptively well, manifesting neither vital signs nor physical examination abnormalities.

This course will discuss life-threatening and non-life-threatening causes of CP and provide an initial approach to evaluating CP patients stressing the collection of the health history and physical examination.

Differential Diagnosis

Patients present to the ED with a chief complaint of CP as well as a spectrum of signs and symptoms that could indicate many differential diagnoses. Of these differentials are both common conditions and those that are more life-threatening requiring decisive action (Hollander & Chase, 2021).

Most Common Conditions Causing Chest Pain

A brief description of diseases that commonly occur among patients complaining of CP include (Hollander & Chase, 2021):

  • Cardiac Causes of CP Include:
    • Acute heart failure is frequently associated with chest discomfort.
    • Patients with stable angina can usually identify their anginal CP and relay a history of exertional triggers.
    • Valvular heart disease, such as mitral valve prolapse and aortic stenosis, may cause chest discomfort, signify worsening valvular function.
    • Infectious or inflammatory causes of chest discomfort include pericarditis, myocarditis, and endocarditis.
    • Accumulation of pericardial fluid can result in chest discomfort, as can cardiac arrhythmias, especially if coronary blood flow is impaired.
  • Pulmonary/Pleural Causes of CP Include:
    • Respiratory infections, such as pneumonia, tracheitis, and bronchitis, are frequently accompanied by chest discomfort and cough.
    • Chest tightness is a common complaint with asthma exacerbations.
    • Several disease processes can increase pulmonary arterial pressures and resultant right-sided heart dysfunction (cor pulmonale).
    • Pulmonary malignancy can cause CP, particularly if there is pleural involvement.
    • Chest heaviness or discomfort may be noted with pleural effusions.
  • Gastrointestinal Causes of CP Include:
    • Gastroesophageal reflux disease (GERD)
    • Esophageal spasm
    • Esophageal rupture (Boerhaave's Syndrome)
    • Gastroesophageal inflammation
    • Sliding hiatal hernia
    • Pancreatitis (pain from pancreatitis can be referred to the chest)
  • Musculoskeletal Causes of CP Include:
    • Costochondritis
    • Intercostal muscle strains
    • Rib contusions
    • Rib fractures
  • Psychiatric Causes of CP Include:
    • Patients with panic attacks often complain of chest tightness and a sense of impending doom. This cause remains a diagnosis of exclusion.
  • Less commonly encountered conditions that may manifest as CP include:
    • Herpes zoster
    • Referred pain
    • Pain associated with various inflammatory conditions and collagen vascular diseases including:
      • Kawasaki's disease
      • Systemic Lupus Erythematosus (SLE)
      • Polyarteritis nodosa
      • Sarcoidosis
      • Scleroderma
      • Takayasu's arteritis

Life-Threatening Conditions

Causes of CP that pose an immediate threat to life include (Hollander & Chase, 2021):

  • Acute Coronary Syndrome (ACS)
  • Acute aortic dissection
  • Pulmonary embolism (PE)
  • Tension pneumothorax
  • Pericardial (cardiac) tamponade
  • Esophageal rupture (Boerhaave syndrome) leading to mediastinitis

Clinical Approach to Diagnosis

Thoracic organs share afferent nervous system pathways. This pathophysiology creates significant overlap in the symptoms patients experience when thoracic organs develop the disease, making it difficult to distinguish which organ system is involved purely based on history (Hollander & Chase, 2021). Patient descriptions of their symptoms can be helpful in some instances, but clinicians must guard against premature diagnostic closure based upon history (Hollander & Chase, 2021). Several studies demonstrate that so-called "atypical" presentations occur more often than was previously thought and misinterpretation of such presentations increases the risk for misdiagnosis and adverse outcomes (Hollander & Chase, 2021).

The clinician initially assesses all patients with acute CP for life-threatening causes (Hollander & Chase, 2021). Often a definitive diagnosis cannot be made at first and additional testing is performed parallel with management. The patient's history, comorbidities, and symptoms description help narrow the scope of potential diagnoses and stratify the patient's risk for life-threatening disease (Hollander & Chase, 2021). The physical examination focuses on vital sign abnormalities and cardiac or pulmonary findings and may support a diagnosis (Hollander & Chase, 2021).

Health History: Pain

Detailed health history of the patient's CP should be obtained, including (Hollander & Chase, 2021):

  • Onset of Pain:
    • Abrupt or gradual.
    • Pain that starts suddenly and is severe at onset is associated with acute aortic dissection, pneumothorax, and PE.
    • Chest pain associated with PE can begin suddenly but may worsen over time.
    • Nontraumatic pneumothorax most often occurs suddenly at rest, without any precipitating event.
    • A history of forceful vomiting preceding symptoms in a toxic-appearing patient raises concern for a ruptured esophagus and mediastinitis. However, a significant portion of patients who rupture their esophagus give no history of vomiting and presentations vary.
    • Discomfort from an ACS typically starts gradually and may worsen with exertion.
    • With stable angina, discomfort occurs only when activity creates an oxygen demand that outstrips supply limitations imposed by a fixed atherosclerotic lesion. This discomfort occurs at relatively predictable points and changes slowly over time.
    • Unstable angina (UA) represents an abrupt change from baseline functioning, which may manifest as discomfort that begins at lower levels of exercise or rest.
  • Provocation/Palliation:
    • Activities which provoke pain (provocation) and activities which alleviate pain (palliation).
  • Quality of Pain:
    • Sharp, squeezing, pleuritic, etc.
    • Patients often describe the symptoms of an ACS as discomfort rather than pain.
      • The discomfort may be described as pressure, heaviness, tightness, fullness, or squeezing.
      • Ischemia is less likely if the discomfort is knifelike, sharp, pleuritic, or positional.
      • The classic location of ACS is substernal or in the left chest and radiation to the arm, neck, jaw, back, abdomen, or shoulders may occur.
      • Pain that radiates to the shoulders or occurs with exertion significantly increases the relative risk for ACS.
      • Beware of "atypical" presentations of ACS, which are common and occur more often in the elderly, diabetics, and women.
        • Patients with "atypical" symptoms (e.g., dyspnea, weakness) associated with their myocardial infarction (MI) fare worse than patients who experience typical symptoms, likely due to delays in diagnosis and treatment.
      • A PE can create different kinds of pain or painless dyspnea. Pain associated with PE may worsen with deep inspiration and may localize to the chest wall.
      • Patients with pneumothorax report ipsilateral CP, which may initially be sharp and pleuritic but may become dull or achy over time.
      • The discomfort of pericarditis is classically positional, i.e., worse when lying supine and relieved somewhat when leaning forward. It may also worsen with deep inspiration.
      • Sharp, well-localized pain reproduced with movement or palpation of the chest wall is characteristic of musculoskeletal causes.
        • Often the patient relates a history of trauma or strenuous activity before developing pain.
      • Burning pain in the chest and epigastrium is commonly associated with gastrointestinal causes.
        • Esophageal rupture can cause CP or abdominal pain.
          • Cardiac disease can cause identical symptoms, however, and clinicians must avoid prematurely attributing such symptoms to gastrointestinal disease.
  • Radiation of Pain:
    • To the shoulder
    • To the jaw
    • To the back, etc
  • Site of Pain:
    • Substernal
    • Chest wall
    • Back
    • Diffuse vs. localized
  • Timing of Pain:
    • Constant or episodic
    • Duration of episodes
    • Where the pain began

Health History: General Inquiry

  • Inquire about prior diagnostic studies (e.g., stress test or coronary CT angiography, etc.) for similar symptoms or prior procedures (e.g., cardiac catheterization).
  • Ask whether the discomfort is similar to a prior illness(es).
  • Inquire about associated symptoms, such as nausea, vomiting, diaphoresis, dyspnea, syncope, and palpitations.

While conducting your health history regarding their present condition, keep in mind the following points that you can specifically ask your patient about (Hollander & Chase, 2021)

Acute Coronary Syndrome (ACS)

  • Diaphoresis, nausea, and vomiting frequently accompany chest discomfort associated with ACS but are not predictive of ACS.
  • Elderly patients with ACS may only complain of symptoms other than CP, such as:
    • Altered mental status
    • Dyspnea
    • Syncope
    • Weakness
  • Symptoms, such as diaphoresis and nausea, may also occur with nonischemic CP, including:
    • Acute heart failure
    • Aortic dissection
    • Esophageal spasm
    • PE

Acute Aortic Dissection

  • Acute aortic dissection has a wide range of potential associated symptoms, depending on the arterial branches involved, which may confound the diagnosis.
  • According to one review, syncope accompanies 13% of dissections involving the ascending aorta.
  • Neurological symptoms, ranging from hoarseness to paraplegia and altered mental status, occur in 18% to 30% of patients with aortic dissection.
  • ACS can occur when the dissection involves the coronary arteries.

Specific Symptoms

  • Dyspnea frequently accompanies pulmonary causes of CP and may be the predominant symptom in:
    • PE
    • Pneumonia
    • Pneumothorax
  • Tachypnea is common with PE and may be accompanied by wheezing and fever.
  • Young, healthy patients may manifest only relative tachypnea or tachycardia despite the presence of pneumonia or PE.
  • Dyspnea is often the only complaint among elderly patients with ACS.
  • Cough, syncope, and hemoptysis may occur with PE and valvular heart disease (particularly mitral stenosis).
  • Cough and hemoptysis are more common with bronchitis, pharyngitis, or exacerbations of COPD.
  • Dyspnea and cough may accompany pericardial and pleural effusions regardless of etiology.
  • Nausea and belching frequently accompany gastrointestinal causes of CP but can also occur in patients with an inferior MI.
  • Palpitations experienced.
  • Fever raises concern for infectious causes but is also associated with:
    • Acute MI (rarely)
    • Myocarditis
    • Pericarditis
    • PE (usually low-grade)
  • Inquire about preceding or concomitant symptoms, such as fever or peripheral edema.
  • Preceding or concomitant pain and swelling in an extremity suggests deep venous thrombosis (DVT) complicated by PE.
    • DVT occurs most often in the lower extremities, but clots may also originate in the upper extremities and the large veins of the pelvis, where they may produce bilateral lower extremity swelling if the inferior vena cava becomes occluded.

Risk Factors

Inquire about risk factors for life-threatening illness, including:

  • ACS
  • Acute aortic dissection
  • PE

Comorbidities

Inquire about comorbidities such as:

  • Bicuspid aortic valve
  • Connective tissue disorders
  • Current or recent pregnancy
  • Diabetes Mellitus (DM)
  • Hypertension (HTN)
  • Malignancy
  • Peripheral Arterial Disease (PAD)

Past Medical History

  • Inquire about recent events such as:
    • Diagnostic procedures (such as endoscopy, aortic catheterization)
  • Many patients with CP have undergone diagnostic testing for prior episodes, the results of which may be useful.
    • For example, a recent cardiac catheterization or coronary CT angiogram with normal or minimally diseased vessels virtually eliminates the possibility of an ACS.
    • An observational study of 1,977 consecutive patients with coronary arteriograms documenting minimal (i.e., less than 25%) stenosis or normal coronary arteries found that 98% of these patients were free of MI 10 years later. Other studies confirm this data (Hollander & Chase, 2021).
    • Conversely, a prior negative stress test is not useful to rule out ACS in patients with active CP.
  • Major surgery
  • Past physical trauma

Family History

  • Inquire about family history of CP
  • Also ask about family history of heart disease, lung disease, or any of the above life-threatening emergencies that often present with CP

Social History

  • Inquire about drug use (cocaine etc.)
  • Ask about use of cigarettes and other forms of tobacco/nicotine
  • Recent periods of immobilization (long plane ride, etc.)

Physical Examination

Most often, the physical examination does not help distinguish patients with ACS from those with noncardiac CP (Hollander & Chase, 2021). In some instances, physical findings suggest a specific noncardiac diagnosis. Patients with an immediately life-threatening cause for their CP tend to appear anxious and distressed and may be diaphoretic and dyspneic (Hollander & Chase, 2021).

Physical examination findings in patients with acute aortic dissection may be absent or suggestive of end-organ ischemia due to aortic branch vessel occlusion, including MI, stroke, acute intestinal ischemia, or extremity ischemia depending on the affected arteries (Hollander & Chase, 2021). Discrepancies in pulses or blood pressure are notable findings when present but occur infrequently.

In the International Registry of Acute Aortic Dissection (IRAD), signs of dissection included (Evangelista et al., 2018):

  • Murmur of aortic insufficiency (32%)
  • Pulse deficit (15%)
  • Signs of shock or cardiac tamponade (8%)
  • Acute heart failure (7%)
  • Cerebrovascular accident (CVA) (5%)
  • Other neurologic symptoms (up to 30%) include:
    • Horner syndrome
    • Paraparesis
    • Paraplegia

CP associated with focal wheezing or asymmetric extremity swelling raises concern for PE. Most often, patients with PE have a normal extremity examination (Hollander & Chase, 2021).

Unilateral decreased breath sounds may be noted with pneumothorax, but subcutaneous emphysema is uncommon.

With or without an S3 gallop, pulmonary crackles are associated with left ventricular dysfunction and left-sided heart failure, possibly due to ACS (Hollander & Chase, 2021).

Jugular venous distention (JVD), hepatojugular reflux, and peripheral edema suggest right-sided heart failure, possibly due to ACS or PE (Hollander & Chase, 2021). A new systolic murmur is an ominous sign, which may signify papillary muscle dysfunction or a ventricular septal defect (VSD) (Hollander & Chase, 2021). Clinicians may hear a pericardial friction rub in patients with pericarditis. Hamman's crunch is a crackling sound similar to a pericardial friction rub heard over the mediastinum in patients with mediastinal emphysema.

Epigastric tenderness and heme-positive stool suggest a possible gastrointestinal source for pain (Hollander & Chase, 2021).

Acute Coronary Syndrome (ACS)

Coronary vascular disease (CVD) remains the leading killer of adults in developed countries (Hollander & Chase, 2021). The 28-day case mortality rate for an ACS among patients in developed nations is approximately 10% but varies with the severity of the disease and the treatment provided (Hollander & Chase, 2021). Less than 15% to 30% of patients who present with nontraumatic CP have ACS, including MI and UA (Hollander & Chase, 2021).

Pathophysiology

ACS results from atherosclerotic plaque rupture and thrombus formation via the adhesion, activation, and aggregation of platelets (Hollander & Chase, 2021). Coronary blood flow is reduced, and myocardial ischemia occurs (Hollander & Chase, 2021). The degree and duration of the oxygen supply-demand mismatch determines whether the patient develops reversible myocardial ischemia without injury (UA) or myocardial ischemia with injury (MI) (Hollander & Chase, 2021).

Risk Factors

The main factors that increase patient’s risk of ACS include:

  • Age over 55 years
  • Diabetes mellitus
  • Family history of coronary artery disease (CAD)
  • Hypercholesterolemia
  • Hypertension (HTN)
  • Male sex
  • Tobacco use

In addition, cocaine or amphetamine use raises concern for ACS regardless of other risk factors (Hollander & Chase, 2021). Cocaine increases the metabolic demands of the heart via its stimulant effects, causes coronary artery vasoconstriction, and promotes thrombus formation in patients who may otherwise be at low risk for ACS (Hollander & Chase, 2021).

Three Traditional Types

The term ACS is applied to patients with suspicion or confirmation of acute myocardial ischemia or acute MI (Simons & Alpert, 2021). The three traditional types of ACS include (Simons & Alpert, 2021):

  • Non-ST-elevation myocardial infarction (NSTEMI)
  • ST-elevation MI (STEMI)
  • UA

Definition of MI

The 2018 joint task force of the European Society of Cardiology (ESC), American College of Cardiology Foundation (ACCF), the American Heart Association (AHA), and the World Health Federation (WHF) defined MI, whether STEMI or NSTEMI, as the presence of acute myocardial injury detected by abnormal cardiac biomarkers in the setting of evidence of acute myocardial ischemia (Simons & Alpert, 2021). The joint task force further refined the definition of MI by developing a clinical classification according to the assumed proximate cause of the myocardial ischemia (Simons & Alpert, 2021).

STEMI vs. NSTEMI

The terms STEMI and NSTEMI are most correctly used in patients who (Simons & Alpert, 2021):

  • Present with clinical characteristics compatible with myocardial ischemia and who demonstrate elevated troponin levels in the blood.
  • Are found to have an elevated troponin level (with other evidence of ischemia such as symptoms or ECG changes) performed after a coronary revascularization procedure.
  • In the setting of MI after noncardiac surgery when other evidence of ischemia is present. However, management may differ slightly based on ECG changes and the clinical setting.

Unstable Angina (UA)

The diagnosis of UA is uncommon in the era of high-sensitivity troponin (Simons & Alpert, 2021).

New-Onset Angina

The natural history of new-onset angina depends in part upon the degree of exertion required to induce CP.

  • Patients with new-onset angina occurring only after heavy physical exertion, such as shoveling snow or lifting a 50-pound weight, have a prognosis similar to patients with chronic stable angina.
  • In comparison, new angina occurring after minimal exercise or at rest, particularly if prolonged, carries a worse prognosis in the absence of intervention.

Rest Angina

Rest angina, particularly prolonged or associated with transient ST-segment changes >0.05 mV, identifies patients at increased risk.

Early Post-MI Angina

Early post-infarction angina (defined as CP occurring within 48 hours after an acute MI) is typically associated with complex lesions, persistent intracoronary thrombus, and more severe coronary disease.

The recurrent CP may signify either remaining viable myocardium in the infarct zone or a different area of myocardium at risk. Angina occurring soon after an acute MI is associated with high risk in the absence of intervention (Simons & Alpert, 2021).

Patients with recurrent ischemia that was refractory or responsive to medical therapy had a higher rate of reinfarction at 30 days and six months (Simons & Alpert, 2021).

Additionally, refractory ischemia was associated with higher mortality than responsive ischemia or no ischemia at 30 days and one year (Simons & Alpert, 2021).

Post-Revascularization Angina

Angina after percutaneous coronary intervention (PCI) or coronary artery bypass graft surgery (CABG) can reflect a procedural event. In addition, over the long-term, restenosis after PCI, stenosis in a graft (usually with saphenous vein grafts), or progression of the native disease can also result in post-CP.

Periprocedural Angina:

A periprocedural ischemic event may occur with or without symptoms, with or without troponin elevation, and either at the site of PCI or remotely (Simons & Alpert, 2021).

Ischemic CP (with or without troponin elevation) within 48 hours after stenting usually results from:

  • Distal embolization of atherosclerotic or thrombotic debris.
  • Procedural events such as abrupt vessel closure (usually due to stent thrombosis or progression of an untreated dissection).
  • Side branch occlusion.
  • Transient coronary spasm.

Other patients have asymptomatic enzyme elevations indicative of procedural-related myocardial injury of a type 4 MI if the troponin level is above five times the upper reference limit. There is clinical evidence of ischemia on the ECG or an event during or after, or after the event after PCI, such as stent thrombosis (Simons & Alpert, 2021). On occasion, periprocedural ischemia early after PCI may occur at the stenotic lesions not addressed at the time of the procedure. It is important to note that ECG changes are associated with a worse prognosis (Simons & Alpert, 2021).

An important diagnostic consideration soon after PCI is the distinction between ischemic and nonischemic CP.

  • Nonischemic CP is typically manifested at rest, without ECG changes or elevation of cardiac enzymes.
  • Most patients describe pain characteristics different from their typical angina (more localized and frequently pleuritic). This discomfort lasts for less than 72 hours in about 80% of patients and less than two weeks in the remainder (Simons & Alpert, 2021). Overexpansion of the stent is thought to be responsible in most cases (Simons & Alpert, 2021).

Recurrent angina during the postoperative period after a CABG is usually due to a technical problem with a graft or with early graft closure (Simons & Alpert, 2021). It is, therefore, an indication for prompt catheterization with revascularization by PCI, if feasible. The diagnosis of recurrent ischemia may be difficult after a CABG since cardiac enzyme elevations occur due to the surgical procedure, and ECG changes may reflect postoperative pericardial inflammation (Simons & Alpert, 2021).

Late Angina:

The delayed onset of angina (30 days or more after PCI) can reflect restenosis after PCI, graft stenosis after CABG, or progression of the native disease (Simons & Alpert, 2021). Affected patients typically present with the gradual and progressive return of effort angina. Prompt stress testing should be performed since these patients are at increased risk.

While less common, some patients with recurrent ischemia present with UA. Such patients should be evaluated with cardiac catheterization after adequate medical stabilization (Simons & Alpert, 2021).

NSTEMI can also occur in patients with prior CABG. These patients have an increased rate of significant coronary events. The older the saphenous vein graft, the higher the likelihood that UA is due to a culprit lesion within the graft. Grafts are more likely than native vessels to show total occlusion or thrombus, complications that are more refractory to medical therapy (Simons & Alpert, 2021). Among patients who undergo PCI for saphenous vein graft disease, restenosis is manifested by UA presentation in 25% of patients (Simons & Alpert, 2021).

Absence of Significant Coronary Disease

In different clinical trials and the CRUSADE registry, 9% to 14% of patients with a non-ST elevation ACS have either normal vessels or no vessel with ≥50% to 60% stenosis on coronary angiography (Simons & Alpert, 2021). Possible mechanisms for the absence of significant coronary disease in these patients include (Simons & Alpert, 2021):

  • Coagulopathy
  • Coronary microvascular dysfunction
  • Coronary thrombosis with rapid clot lysis
  • Macro- and micro-emboli
  • Myocarditis
  • Small vessel disease
  • Vasculitis
  • Vasospasm

The strongest independent predictors of insignificant coronary disease were (Simons & Alpert, 2021):

  • Absence of enrollment MI, prior angina, diabetes, or ST-segment depression
  • Female sex
  • Younger age

Patients with a non-ST elevation ACS who do not have significant coronary disease have a better outcome than those with a culprit coronary lesion.

Myocardial Ischemia

The clinical presentation of myocardial ischemia is most often acute chest discomfort (Reeder et al., 2021). The goal of evaluation is to determine the cause of such discomfort or other related symptoms (e.g., dyspnea, weakness) and promptly initiate appropriate therapy. Initial assessment and management must be rapid but methodical and evidence-based.

An immediate cardiology consultation should be available for cases where the initial diagnosis and treatment plan are unclear or not addressed directly by available protocols (Reeder et al., 2021). Several life-threatening conditions can cause CP and dyspnea. It is important to avoid premature diagnostic closure.

Diagnostic evaluation emphasizes distinguishing between the following potential, life-threatening causes of CP:

  • ACS: MI or UA
  • Nonischemic CP, including potentially life-threatening conditions such as:
    • Aortic dissection
    • Esophageal rupture
    • PE

The diagnosis of acute coronary-related ischemia depends upon the:

  • Abnormalities on the ECG
  • Characteristics of the CP (if present)
  • Levels of serum markers of cardiac injury
  • Specific associated symptoms

Clinical Presentation of Ischemic Chest Pain

Certain characteristics of the patient's chest discomfort and associated symptoms increase the likelihood of ACS, while others make the diagnosis unlikely.

Notably, older patients, diabetics, and women are more likely to present with dyspnea, weakness, nausea and vomiting, palpitations, and syncope and may not manifest chest discomfort (Reeder et al., 2021).

Ischemic chest pain has several features that tend to distinguish it from noncardiac pain (Reeder et al., 2021). These characteristics are described using the OPQRST mnemonic (Reeder et al., 2021).

Onset

Ischemic pain is typically gradual in onset, although the intensity of the discomfort may wax and wane.

Provocation and Palliation

Ischemic pain is generally provoked by activity, such as exercise, that increases cardiac oxygen demand. Ischemic pain does not change with respiration or position. It may or may not respond to nitroglycerin and, if there is an improvement, this may only be temporary. Relief of ischemic pain following the administration of therapeutic interventions (e.g., nitroglycerin, "gastrointestinal cocktail" of viscous lidocaine, and antacid) does not reliably distinguish nonischemic from ischemic CP.

Quality

Ischemic pain is often characterized more like discomfort than pain and it may be difficult for the patient to describe. Terms frequently used by patients to describe ischemic pain include:

  • Ache
  • Band-like sensation
  • Burning
  • Constriction
  • Crushing
  • Fullness in the chest
  • Heartburn
  • Heavy weight on chest (elephant sitting on chest)
  • Knot in the center of the chest
  • Like a bra too tight
  • Lump in throat
  • Pressure
  • Strangling
  • Squeezing
  • Tightness
  • Toothache (when there is radiation to the lower jaw)

Ischemic pain is not generally described as sharp, fleeting, knife-like, stabbing, or like "pins and needles." Increased pain severity does not appear to correlate with an increased likelihood of acute MI. In some cases, the patient cannot qualify the nature of the discomfort but places their clenched fist in the center of the chest, known as the "Levine sign” (Reeder et al., 2021).

Radiation

Ischemic pain often radiates to other parts of the body, including:

  • Arms (upper and forearm)
  • Back (specifically the interscapular region)
  • Fingers
  • Lower jaw and teeth (but not upper jaw)
  • Neck
  • Shoulders
  • Throat
  • Upper abdomen (epigastrium)
  • Wrist

The old dictum that "pain above the nose or below the navel is rarely cardiac in origin" still holds. Pain radiating to the upper extremities is highly suggestive of ischemic pain (Reeder et al., 2021).

Site

Ischemic pain is not felt in one specific spot. Ischemic pain is a diffuse discomfort that may be difficult to localize. The patient often indicates the entire chest rather than localizing it to a specific area by pointing a single finger.

Time Course

Angina is usually brief (two to five minutes) and is relieved by rest or with nitroglycerin.

In comparison, patients with an ACS may have CP at rest and the duration is variable but generally lasts longer than 30 minutes. Classic anginal pain lasting more than 20 minutes suggests ACS. Continuous pain that does not wax and wane and persists for over 24 hours is unlikely due to ACS (Reeder et al., 2021).

Additional Information Regarding General Clinical Presentation

Symptoms associated with the highest relative risk of MI include (Reeder et al., 2021):

  • Pain associated with diaphoresis or with nausea and vomiting.
    • Importantly, the question is whether the current pain is reminiscent of a prior MI.
    • Notably, no one pain characteristic has sufficient positive or negative predictive value to diagnose or exclude ACS definitively.
  • Radiation to an upper extremity, particularly when there is radiation to both arms.

Historical Features Increasing the Likelihood of ACS:

  • Patients with a prior history of ACS have a significantly increased risk of recurrent ischemic events
  • A prior history of other vascular disease is associated with a risk of cardiac ischemic events comparable to that seen with a prior history of ACS
  • Risk factors for ACS:
    • Age
    • Male sex
    • History of diabetes, HTN, and/or dyslipidemia
    • Use of cigarettes
    • Recent use of cocaine or other sympathomimetic drugs (e.g., methamphetamine)

Associated Symptoms:

Ischemic pain is often associated with other symptoms such as (Reeder et al., 2021):

  • Belching
  • Clamminess
  • Diaphoresis
  • Dizziness
  • Dyspnea (most common), which may reflect mild pulmonary congestion resulting from ischemia-mediated diastolic dysfunction
  • Fatigue
  • Indigestion
  • Lightheadedness
  • Nausea
  • Vomiting

Noncardiac Chest Pain:

Specific CP characteristics can be used to help differentiate cardiac from noncardiac causes. Systematic reviews have identified the following characteristics as more typical of nonischemic chest discomfort (Reeder et al., 2021):

  • Any discomfort localized with one finger
  • Any discomfort reproduced by movement or palpation
  • Constant pain lasting for days
  • Fleeting pains lasting for a few seconds or less
  • Pain radiating into the lower extremities or above the mandible
  • Pleuritic pain, sharp or knife-like pain related to respiratory movements or cough
  • Primary or sole location in the mid or lower abdominal region

However, some patients with ACS present with so-called "atypical" CP:

Some patients who appear to have a noncardiac cause of CP have other serious conditions, including acute aortic dissection, PE, tension pneumothorax, myocarditis, perforating peptic ulcer, and esophageal rupture (Reeder et al., 2021). It is essential to consider these alternate diagnoses to avoid potentially dangerous errors in management, such as administering antiplatelet, anticoagulant, or thrombolytic therapy to a patient with an aortic dissection.

Atypical Symptoms

Some patients with ACS present with atypical symptoms rather than CP (Reeder et al., 2021). In a review of over 430,000 patients with confirmed acute MI from the National Registry of Myocardial Infarction II, one-third had no CP on presentation. These patients often present with symptoms such as:

  • Cardiac arrest
  • Dyspnea alone
  • Epigastric pain or discomfort
  • Nausea or vomiting
  • Palpitations
  • Syncope
  • Weakness

Patients that present with atypical symptoms are more likely to be:

  • Diabetic
  • Older
  • Female

The absence of CP has important implications for therapy and prognosis. In the Registry report, patients without CP were much less likely to be diagnosed with a confirmed MI on admission (Reeder et al., 2021). These patients were also less likely to be treated with appropriate medical therapy and receive thrombolytic therapy or primary PCI. Not surprisingly, these differences were associated with increased in-hospital mortality.

Physical Examination

The initial physical examination should focus on findings that permit rapid triage and aid in immediate diagnosis and management. It should include an examination of the following (Reeder et al., 2021):

  • Responsiveness, airway, breathing, and circulation
    • In patients in respiratory or cardiorespiratory arrest, the appropriate resuscitation algorithms should be followed.
  • Evidence of systemic hypoperfusion (hypotension, tachycardia, impaired cognition, cool, clammy, pale, ashen skin)
    • Cardiogenic shock complicating acute MI requires aggressive evaluation and management.
  • Evidence of heart failure (jugular venous distention, new or worsening pulmonary crackles, hypotension, tachycardia, new S3 gallop, new or worsening mitral regurgitation murmur)
    • Aggressive management is needed for patients with heart failure complicating an acute MI, depending upon the severity of the heart failure and the presence of other risk factors.
  • Focused neurologic examination
    • A screening neurologic examination should be performed to assess for focal lesions or cognitive deficits that might preclude safe use of thrombolytic therapy.

Impact of Missed Diagnosis

Patients whose diagnosis is missed initially have an increase in short-term mortality (Reeder et al., 2021). This issue was evaluated in a review of 10,689 patients who presented with symptoms suggesting acute coronary-related ischemia: 8% had an acute MI, and 9% had unstable angina (Reeder et al., 2021). Among the patients with an ACS, 2.2% were mistakenly discharged from the ED (Reeder et al., 2021). An atypical presentation most frequently led to a missed diagnosis. The patients with missed MI had the following characteristics:

  • Dyspnea as the major presenting symptom
  • Non-white
  • Normal or nondiagnostic ECG
  • Women less than 55 years of age

Acute Aortic Dissection

Aortic dissection is relatively uncommon, but it often presents acutely as a catastrophic illness with severe CP or back pain and acute hemodynamic compromise. Early and accurate diagnosis and treatment are crucial for survival.

Definition and Pathophysiology

Acute aortic dissection is defined as a separation of the aortic wall layers due to an intimal tear (Black & Manning, 2021a).

Spontaneous Acute Aortic Dissection

For spontaneous dissection, it is uncertain whether the initiating event is a primary rupture of the intima with secondary dissection of the media or primary hemorrhage within the media and subsequent rupture of the overlying intima.

The initial intimal tear can occur in the ascending or descending aorta and occasionally originate in the abdominal aorta. This tear occurs when (Black & Manning, 2021a):

  • Blood at high pressure passes through the tear and separates the intima from the media or adventitia, creating a false lumen.
  • The dissection can propagate proximally or distally from the initial tear to involve the aortic valve, coronary arteries, or thoracic or abdominal aorta branches.
    • Such propagation is responsible for many associated clinical features of aortic dissection (acute CP or back pain, neurologic symptoms).
    • A higher mean pressure in the false lumen can cause dynamic or static compression and occlusion of the true lumen with malperfusion of the aorta branches, resulting in end-organ ischemia (coronary, cerebral, spinal, extremity, visceral).
    • Aortic regurgitation, coronary ischemia, and cardiac tamponade can occur if the dissection progresses proximally to involve the aortic valve and coronary arteries or the pericardial sac.
    • Additionally, multiple communications may form between the true lumen and the false lumen.

Abdominal aortic dissection can occur as an extension to a thoracic aortic dissection with the intimal flap located in the proximal or descending thoracic aorta, or it can occur in isolation (Black & Manning, 2021a):

  • Isolated abdominal aortic dissection is reported occasionally and can be due to spontaneous, iatrogenic, or traumatic mechanisms.
  • The infrarenal abdominal aorta is more commonly involved than the suprarenal aorta.
    • In one review of 52 reported cases, the entry site for spontaneous isolated abdominal aortic dissections (SIAADs) most commonly occurred between the renal arteries and inferior mesenteric artery.
      • A concomitant abdominal aortic aneurysm was identified in 40% of patients and indicated the need for repair.

Iatrogenic or Traumatic Acute Aortic Dissection

Aortic dissection that does not occur spontaneously can be due to instrumentation or trauma (Black & Manning, 2021a). Traumatic tears typically involve the descending thoracic aorta just distal to the subclavian artery. Iatrogenic or traumatic injury (e.g., intra-aortic balloon pump placement, rapid deceleration motor vehicle accident) was responsible for 6% of cases of intramural aortic hematoma in one review (Black & Manning, 2021a).

Risk Factors

Common factors include (Hollander & Chase, 2021):

  • Patients with systemic HTN and atherosclerotic disease in their seventh decade of life
  • Patients with acquired or congenital conditions that weaken the structural architecture of the aortic wall
  • Patients <40 years of age with:
    • Bicuspid aortic valve
    • Cocaine use
    • Connective tissue disorders, such as Marfan's syndrome
    • Pregnancy (particularly in combination with bicuspid aortic valve or connective tissue disease)
    • Previous aortic surgery
    • Recent cardiac surgery
    • Recent aortic instrumentation

According to one prospective observational study, the probability of aortic dissection increases significantly with the presence of the following findings (Hollander & Chase, 2021):

  • History:
    • Pain in the chest, back, or abdomen is described as abrupt in onset, of severe intensity, or a ripping/tearing sensation.
  • Physical examination:
    • Physical examination findings of perfusion deficit, systolic blood pressure difference (>20 mmHg difference between the right and left arm), or of focal neurologic deficit, or an aortic diastolic murmur and hypotension or shock.
  • Chest CXR:
    • Mediastinal or aortic widening

According to this study, aortic dissection occurs in approximately 83% of patients with classic aortic dissection pain and suggestive CXR findings. It also occurs in approximately 92% of patients with classic pain and an absent pulse or significant difference in blood pressure (Hollander & Chase, 2021). When all three variables coexist, aortic dissection is present in all patients. When no variable is present, approximately 7% of patients have aortic dissection (Hollander & Chase, 2021).

Variants of Aortic Dissection

Aortic Intramural Hematoma

Aortic intramural hematoma is defined as a hematoma confined within the medial layer of the aorta in the absence of a detectable intimal tear, although microtears may be present (Black & Manning, 2021a). A rupture of the vasa vasorum probably produces the false channel into the media of the aortic wall. It can occur in the absence of significant atherosclerosis or with a concomitant atherosclerotic ulcer.

The absence of an intimal lesion distinguishes intramural aortic hematoma from the hematoma that may be associated with a penetrating aortic ulcer, for which there is a clear break in the intima (Black & Manning, 2021a). Aortic intramural hematoma can be a precursor to acute aortic dissection. In different series, intramural aortic hematoma accounted for 5% to 20% of patients with symptoms consistent with aortic dissection (e.g., acute aortic syndrome) (Black & Manning, 2021a).

The mechanism by which an intramural hematoma is created is not certain. Two mechanisms have been described (Black & Manning, 2021a):

  1. Rupture induced by a penetrating atherosclerotic ulcer
  2. Spontaneous rupture
    1. Spontaneous rupture of the vasa vasorum as pathogenesis has not been proven
      1. In this scenario, the false lumen originates from spontaneous rupture of the vasa vasorum into the media of the aortic wall because there is no continuous flow. The blood contained within the wall quickly thromboses

Some believe that intramural hematoma represents acute aortic dissection with thrombosis of the false lumen and that an intimal tear is always present whether or not it is identified (Black & Manning, 2021a). Intimal defects have been identified surgically and radiographically in approximately 70% of cases initially diagnosed as intramural hematoma (Black & Manning, 2021a). However, there appears to be a difference in the affected plane of the aortic media. The outer media (toward the adventitia) is thinner for intramural hematoma, which may explain the higher risk of rupture for intramural hematoma than acute dissection. Between 8% and 16% will evolve into the aortic dissection (Black & Manning, 2021a).

Intimal Tear Without Hematoma

Intimal tear without hematoma is an uncommon variant of aortic dissection characterized by a stellate or linear intimal tear associated with exposure of the underlying aortic media or adventitial layers (Black & Manning, 2021a). There is no separation of the medial layers or progression. Blunt aortic injury with focal tear may manifest in this manner.

Penetrating Aortic Ulcer

Penetrating aortic ulcer refers to a region of the aorta (ulcer-like projection) where the aortic intima is denuded with the lesion progressing through a variable amount of the aortic wall, over which there may or may not be overlying thrombus (Black & Manning, 2021a). Penetrating aortic ulcers are typically associated with atherosclerotic changes of the adjacent aortic wall (Black & Manning, 2021a). These ulcers may be associated with hematoma within the media and may progress to perforation or aortic dissection. Penetrating aortic ulcer is the initiating lesion in <5% of all aortic dissections (Black & Manning, 2021a).

Periaortic Hematoma

Periaortic hematoma represents a contained aortic rupture due to slow oozing from the damaged aorta at or near the site of aortic injury (Black & Manning, 2021a). Periaortic hematoma is more common in intramural aortic hematoma compared with acute aortic dissection. In a review of 971 patients with acute dissections from the International Registry of Acute Aortic Dissections (IRAD), 227 (23%) had a periaortic hematoma (Black & Manning, 2021a). Not surprisingly, patients with periaortic hematoma had higher shock rates, cardiac tamponade, altered consciousness/coma, and a significantly higher mortality rate than those without a periaortic hematoma (Black & Manning, 2021a).

Pathophysiology

Pulsatile blood flow causes propagation of the dissection with subsequent obstruction of branch arteries (e.g., coronary, carotid, mesenteric), leading to ischemic injury to areas perfused by those vessels (Black & Manning, 2021a). In approximately 13% of cases, no intimal tear is identified (Black & Manning, 2021a). Such patients have an acute intramural hematoma likely caused by bleeding of the vasa vasorum with intramural hematoma formation in the aorta wall. The clinical picture of intramural aortic hematoma and other acute aortic syndromes (e.g., penetrating aortic ulcer, aortic rupture) is similar to classic acute aortic dissection (Black & Manning, 2021a).

Dissection typically begins with a tear in the inner layer of the aortic wall (aortic intima), allowing blood to track between the intima (inner layer) and aortic media (middle layer) (Black & Manning, 2021a). Degeneration of the aortic media, or cystic medial necrosis, is a prerequisite for developing nontraumatic aortic dissection. Blood passes into the aortic media through the tear, separating the intima from the surrounding media or adventitia and creating a false lumen. It is uncertain whether the initiating event is a primary rupture of the intima with secondary dissection of the media or hemorrhage within the media and subsequent rupture of the overlying intima. Fifty to 65% of aortic intimal tears originate in the ascending aorta within the sinotubular junction and extend to involve the remaining portions of the thoracoabdominal aorta (Black & Manning, 2021a).

Patients with involvement of the ascending aorta have an imminent risk for aortic rupture. The intimal tear with type B dissection can spiral into a cleavage plane within the media of the aorta along the posterolateral descending thoracic aorta, leaving the celiac artery, superior mesenteric artery, and right renal artery, typically originating in the true lumen, with the left renal artery deriving false lumen flow (Black & Manning, 2021a). Variations in the anatomy of the dissection are typical and underscore the critical need for proper axial imaging. In addition, multiple communications may form between the true lumen and the false lumen.

Approximately 20% to 30% of intimal tears will originate in the vicinity of the left subclavian artery and extend into the descending thoracic and thoracoabdominal aorta (Black & Manning, 2021a). The commonality of these two predominant locales for the development of the aortic tear is hypothesized to be related to shear forces being highest in these regions. The dissection can propagate proximally or distally to involve the aortic valve and enter the pericardial space or branch vessels. Such propagation is responsible for many of the ischemic clinical manifestations, including (Black & Manning, 2021a):

  • Aortic regurgitation
  • Cardiac tamponade
  • Ischemia (coronary, cerebral, spinal, or visceral)

Immediately following dissection, there is "intrinsic true lumen collapse" to a variable degree and false lumen dilation, thus increasing the aortic cross-sectional area (Black & Manning, 2021a). The increase of the false lumen area correlates with blood pressure, the size of the entry tear into the false lumen, the depth of the dissection plane within the media, and the percentage of aortic circumference involved. Because the outer wall of the false lumen is thinned, it expands to generate the necessary wall tension to accommodate aortic pressure. The true lumen collapses due to the pressure differential between the true and false lumens. It may be exacerbated by the intrinsic recoil of the muscular elements within the dissection flap (Black & Manning, 2021a). Malperfusion of aortic branch vessels may occur due to the extension of the dissection throughout the thoracoabdominal aorta. Malperfusion of a vascular bed can occur in one or more branch territories simultaneously. The standard nomenclature of the mechanisms of malperfusion of aortic branch vessels is termed "dynamic obstruction" and "static obstruction” (Black & Manning, 2021a). Malperfusion syndromes may occur in 30% to 45% of descending dissections and correlate with early mortality (Black & Manning, 2021a).

Classifications of Aortic Dissections

By Duration of Symptoms

Aortic dissection is, somewhat arbitrarily, classified as acute or chronic based upon the duration of symptoms at the time of presentation (Black & Manning, 2021a). During the first two weeks (acute phase), life-threatening complications due to branch involvement or aortic rupture are more likely to occur than the past two weeks (chronic phase).

By Anatomic Classification

The two main anatomic classifications used to describe aortic dissection are the (Black & Manning, 2021a):

  1. DeBakey System (Figure 1):
    1. The DeBakey system is based upon the site of origin, with:
      1. Type I involving the ascending aorta, arch, and descending thoracic aorta and may progress to involve the abdominal aorta.
      2. Type 2 originating in and is confined to the ascending aorta.
      3. Type IIIa involving the descending thoracic aorta distal to the left subclavian artery and proximal to the celiac artery.
      4. Type IIIb dissection involving the thoracic and abdominal aorta distal to the left subclavian artery.
  2. Stanford (Daily) System (Figure 1):
    1. The Stanford system is more widely used and classifies dissections that involve the ascending aorta (and may also involve the arch or descending aorta) as:
      1. Type A involving the ascending aorta and may progress to involve the arch and thoracoabdominal aorta.
      2. Type B involving the descending thoracic or thoracoabdominal aorta distal to the left subclavian artery without the involvement of ascending aorta.

classification_of_aortic_dissection

Figure 1: DeBakey and Stanford Systems

Type A ascending aortic dissections are almost twice as common as type B descending dissections (Black & Manning, 2021a). The right lateral wall of the ascending aorta is the most common site. In patients with an ascending aortic dissection, aortic arch involvement occurs in up to 30% (Black & Manning, 2021a).

Isolated abdominal aortic dissection is reported and can be due to iatrogenic, spontaneous, or traumatic mechanisms. The infrarenal abdominal aorta is more commonly involved than the suprarenal aorta. In one review of 52 reported cases, the entry site for spontaneous isolated abdominal aortic dissections (SIAADs) commonly occurred between the renal and inferior mesenteric arteries (Black & Manning, 2021a). A concomitant abdominal aortic aneurysm was identified in 40% of patients and indicated the need for repair (Black & Manning, 2021a).

The Society for Vascular Surgery (SVS) and Society for Thoracic Surgery (STS) classification system is similar to the Stanford system distinguishing type A from type B by the level of involvement. Still, it also specifies the distal extent of the dissection.

By Etiologic Classification

Degenerative:

  • Aortic dissection that has a degenerative etiology is not associated with any known genetically-mediated syndromes.

Genetically-mediated:

  • Genetically mediated thoracic aortic aneurysm/dissection (TAAD) can be part of a syndrome:
    • Syndromic, such as Marfan syndrome, Loeys-Dietz syndrome, vascular Ehlers-Danlos syndrome, or Turner syndrome
    • Nonsyndromic, as with familial TAAD or bicuspid aortic valve

Traumatic:

  • Traumatic aortic dissection can be related to a blunt injury mechanism or iatrogenic related to instrumentation (e.g., catheterization, dissection following aortic repair).

Incidence

The incidence of acute aortic dissection in the general population ranges from 2.6 to 3.5 per 100,000 person-years (Black & Manning, 2021a). Seasonal variation in the incidence of aortic dissection has been described, with winter months associated with higher admission rates for aortic dissection. Although acute aortic dissection can occur at any time of the day, the onset of symptoms more commonly occurs during waking hours.

In a review that included 1,827 patients, 25% occurred between 08:00 and 12:00 (8 am to 12 pm) (Black & Manning, 2021a). Daytime physical activity has also been linked to the onset of acute aortic dissection, particularly in younger patients. A lower incidence was seen in the late evening/early morning hours between 22:00 to 02:00 (11 pm to 2 am) (Black & Manning, 2021a).

Onset of clinical symptoms may follow established patterns of blood pressure elevation and reduction throughout the day. Patients with acute aortic dissection tend to be 60- to 80-year-old men with systemic HTN and atherosclerotic disease (Black & Manning, 2021a). Still, this description alone does not help distinguish it from other life-threatening conditions. In a review of 4,428 patients from IRAD, 66.0% were men, and the mean age was 63 years (Black & Manning, 2021a). Women presenting with aortic dissection are generally older than men (mean age 67 years) and more delayed presentation (Black & Manning, 2021a).

There are some important differences between older adult patients and younger patients with dissections involving the ascending aorta. In an IRAD review, 32% of patients were ≥70 years of age and were significantly more likely to have atherosclerosis, prior aortic aneurysm, iatrogenic dissection, or intramural hematoma (Black & Manning, 2021a). In a review of patients under age 40, only 34% had a history of HTN, and only 1% had a history of atherosclerosis (Black & Manning, 2021a). Marfan syndrome is present in 8.5% of the younger patients (mean age 55 years) and was not seen in any older adult patient (Black & Manning, 2021a). In a separate review, familial dissections also occurred in significantly younger patients compared with degenerative aortic dissection (54 versus 63 years of age) (Black & Manning, 2021a).

Commonly Associated High-Risk Conditions

High-risk conditions commonly associated with aortic dissection include the following (Black & Manning, 2021a).

Hypertension (HTN)

The most important predisposing factor for acute aortic dissection is systemic HTN. In the IRAD review, 76.6% had a history of HTN (Black & Manning, 2021a). HTN was more common in those with a distal (type B) dissection compared with a type A dissection. An abrupt, transient, severe increase in blood pressure has been associated with acute aortic dissection through various mechanisms.

Crack cocaine, which may cause transient HTN due to catecholamine release, accounted for 37% of dissections in an inner-city population report (Black & Manning, 2021a). The mean duration from last cocaine use to the onset of symptoms was 12 hours.

High-intensity weightlifting or other strenuous resistance training can also cause a transient elevation in blood pressure and has been reported as an antecedent (Black & Manning, 2021a).

HTN is also the postulated mechanism when energy drinks or ergotism have been associated with aortic dissection.

Genetically-Mediated Connective Tissue Disorders

Genetically-mediated connective tissue disorders (e.g., Marfan syndrome, Ehlers-Danlos syndrome) weaken the structural architecture of the aortic wall. In an IRAD review, Marfan syndrome was present in 50% of those under age 40, compared with only 2% of older patients (Black & Manning, 2021a). Most patients with Marfan syndrome and aortic dissection have a family history of dissection. There may also be an association between Marfan syndrome and aortic dissection in the third trimester of pregnancy (Black & Manning, 2021a).

Preexisting Aortic Aneurysm

In an IRAD review, 13% of patients had a known aortic aneurysm before dissection (Black & Manning, 2021a). The ascending aorta was more often the site of origin of the dissection than the aortic arch or descending aorta. Such a history was more common in patients under age 40. In a later IRAD review, a known aortic aneurysm was present in 20.7% of patients identified with descending aortic dissection and 12.7% of those with ascending aortic dissection (Black & Manning, 2021a).

Bicuspid Aortic Valve

In an IRAD review, 9% of patients under age 40 with aortic dissection had a bicuspid valve, compared with 1% of those over age 40 and 1% in the general population (Black & Manning, 2021a). Aortic dissection in patients with a bicuspid valve always involves the ascending aorta, usually with severe loss of elastic fibers in the media. The predisposition to dissection may reflect a genetic cause for the defect in the aortic wall, as enlargement of the aortic root or ascending aorta is frequently associated with bicuspid aortic valves, even those that function normally, independent of their function (Black & Manning, 2021a).

Aortic Instrumentation/Surgery

Cardiac surgery or catheterization for coronary or valvular disease can be complicated by aortic dissection. Cardiac catheterization, particularly with femoral artery access, with or without coronary intervention was reported to cause 14 of 723 dissections in a report from IRAD (Black & Manning, 2021a). Ascending aortic dissection is a rare complication of CABG, occurring with both conventional on-pump CABG and, perhaps more often, with minimally invasive off-pump CABG. In a review from a single institution, ascending aortic dissection occurred in 1 of 2,723 patients treated with conventional CABG and 3 of 308 undergoing off-pump CABG (Black & Manning, 2021a). Although rare, other procedures that manipulate the aorta, including carotid or other great vessel interventions and thoracic or abdominal aortic repair (open or endovascular), can also be complicated by aortic dissection.

Aortic Coarctation

Aortic dissection can occur in patients with an aortic coarctation when surgery leaves behind abnormal para coarctation aorta with intrinsic medial faults or when balloon dilatation of native coarctation mechanically damages the inherently abnormal para coarctation aorta (Black & Manning, 2021a).

Familial Thoracic Aortic Aneurysm and Dissection (TAAD)

TAAD refers to patients with thoracic aortic disease associated with a family history of aneurysmal disease but does not meet strict criteria for known connective tissue syndromes (Black & Manning, 2021a). The ascending thoracic aorta is predominantly involved.

Turner Syndrome

Aortic dissection or rupture, often occurring with coarctation, is an increasingly recognized cause of death in women with Turner syndrome. In a survey of 237 patients, at least 15 had aortic dilation (Black & Manning, 2021a). In this survey, all of these cases involved the ascending aorta, 12 individuals had an associated risk factor such as HTN or another cardiovascular malformation (e.g., coarctation), and two individuals had a dissection (Black & Manning, 2021a).

Inflammatory Diseases

The follow diseases that cause vasculitis include (Black & Manning, 2021a):

  • Giant cell arteritis
  • Rheumatoid arthritis
  • Syphilitic aortitis
  • Takayasu arteritis

Trauma

Trauma rarely causes a classic dissection but can induce a localized tear in the region of the aortic isthmus. More commonly, chest trauma from acute deceleration (as in a motor vehicle accident) results in aortic rupture or transection (Black & Manning, 2021a).

Pregnancy & Delivery

Pregnancy and delivery are independent risk factors for aortic dissection. However, the presence of other conditions (e.g., bicuspid aortic valve, Marfan syndrome) may compound the risk. In one review, postpartum aortic dissection occurred in 2 of 31 Marfan pregnancies (Black & Manning, 2021a). A cohort study of administrative claims data, in several states from 2005 through 2013, found a rate of aortic complications of 5.5 per million patients during pregnancy and the postpartum period (Black & Manning, 2021a).

Pregnancy was associated with a significantly increased risk of aortic dissection or rupture than the control period one year later among women with and without documented inherited connective tissue diseases (e.g., Marfan syndrome). However, the risk was significantly greater in those with connective tissue diseases. The authors noted that the findings might reflect prevalent but undiagnosed or undocumented connective tissue disorders, or they may indicate that the physiologic changes of pregnancy can cause aortic injury even in otherwise healthy women (Black & Manning, 2021a).

Fluoroquinolone Use

Observational studies have suggested that fluoroquinolone use may be associated with an increased risk of aortic aneurysm or dissection (Black & Manning, 2021a).

Clinical Features

Signs & Symptoms

Acute aortic dissection has a wide range of potential associated symptoms, depending on the arterial branches involved, which may confound the diagnosis (Black & Manning, 2021a). The symptoms and signs of acute aortic dissection depend upon the extent of the dissection and the affected cardiovascular structures.

Hypertension (HTN)

HTN is present in 70% of type B dissections but only in 25% to 35% of type A dissections (Black & Manning, 2021). The presence of hypotension complicating a type B dissection is rare, seen in less than 5% of patients, and usually implies rupture of the aorta (Black & Manning, 2021a). By contrast, hypotension may be present in 25% of dissections involving the ascending aorta, potentially resulting from aortic valve disruption leading to severe aortic regurgitation or extravasation into the pericardial space leading to cardiac tamponade (Black & Manning, 2021a). Malperfusion of brachiocephalic vessels by the dissection may falsely depress brachial cuff pressures, usually by involving the left subclavian artery origin in the type B dissection patient (Black & Manning, 2021a).

Acute Pain

The most common presenting symptom is pain occurring in over 90% of patients, with 85% noting the onset to be abrupt (Black & Manning, 2021a). Typically, the pain is severe and sharp/knife-like, causing the patient to seek medical attention within minutes to hours of onset, and categorically unlike any pain experienced before (Black & Manning, 2021a).

Pain can occur in isolation or be associated with syncope, a CVA, ACS, heart failure, or other clinical symptoms or signs. ACS can occur when the dissection involves the coronary arteries. The pain is typically described in the anterior chest in an ascending (type A) dissection, but for descending (type B) dissection, the pain is more often experienced in the back.

CP was significantly more common in patients with type A dissections in an IRAD review, while both back pain and abdominal pain were significantly more common with type B dissections (Black & Manning, 2021a). The pain can radiate anywhere in the thorax or abdomen. Unlike the classic description of the character of pain in aortic dissection as ripping or tearing, pain is more often described as sharp and less often as migratory.

Typical symptoms and signs were less common among those >70 years of age, representing almost one-third of patients (Black & Manning, 2021a). Older patients were significantly less likely to have an abrupt onset of pain compared with younger patients. The localization of pain to the abdomen was reported by 21% of patients in type A dissection and 43% of patients in type B dissection (Black & Manning, 2021a). In such patients, a high index of suspicion for mesenteric vascular compromise is warranted.

Pulse Deficit

The presence of impaired or absent blood flow to peripheral vessels is termed a pulse deficit, defined as a weak or absent carotid, brachial, or femoral pulse resulting from the intimal flap or compression by hematoma (Black & Manning, 2021b). A considerable variation (>20 mmHg) in systolic blood pressure may be seen when comparing the blood pressure in the arms.

In IRAD reviews, women are less likely to have a pulse deficit than men (Black & Manning, 2021b). Compared with younger patients, older adult patients (>70 years of age) were significantly less likely to have any pulse deficit. In patients with an aortic arch or thoracoabdominal aorta involvement, pulse deficits are common and occur in 19% to 30% of patients compared with 9% to 21% with a descending aortic dissection (Black & Manning, 2021b).

In the IRAD population, the involvement of the brachiocephalic trunk was noted in 14.5% of patients, the left common carotid artery in 6.0%, the left subclavian artery in 14.5%, and the femoral arteries in 13.0% to 14.0% (Black & Manning, 2021b). Patients presenting with pulse deficits more often had neurologic deficits, coma, and hypotension. Carotid pulse deficits were strongly correlated with fatal CVAs, consistent with prior observations. The number of pulse deficits was also clearly associated with increased mortality. Within 24 hours of presentation (Black & Manning, 2021b):

  • 9.4% of patients with no pulse deficits died
  • 15.8% of patients with one or two deficits died
  • 35.3% of patients with three or more deficits died

For isolated lower extremity pulse deficits, mortality from lower extremity ischemia or its sequelae was uncommon. Nonetheless, leg ischemia caused by acute dissection is a marker of extensive dissection and may be accompanied by other compromised vascular territories (Black & Manning, 2021b). The clinical course of the peripheral ischemia can be quite variable, and up to one-third of this group may demonstrate spontaneous resolution of their pulse deficits.

Patients with a pulse deficit have higher in-hospital complications and mortality rates than those without a pulse deficit. A rapid bedside pulse examination can provide important information in diagnosing acute aortic dissection and those at risk for complications. In a previous report of patients treated during the 1990s, those with peripheral branch obstruction had a mortality rate of 23% compared with 16% for those without obstruction (Black & Manning, 2021b).

In contrast to the IRAD findings, the presence of peripheral vascular complications did not increase mortality. This finding was thought to be due to a timelier diagnosis, prompt initiation of therapy, and the recognition of the importance and appropriate treatment of peripheral vascular complications (Black & Manning, 2021b).

Heart Murmur

Aortic dissection that propagates proximally to the initial tear can involve the aortic valve. A new diastolic murmur in association with severe acute CP is a sign of acute aortic regurgitation (Black & Manning, 2021b). Characteristically, it is a diastolic decrescendo murmur associated with wide pulse pressure, hypotension, or heart failure.

Acute aortic valve regurgitation occurs in one-half to two-thirds of ascending dissections (Black & Manning, 2021b). The murmur of aortic regurgitation related to aortic dissection is most commonly heard along the right sternal border compared with the left sternal border for aortic regurgitation due to primary aortic valve disease.

The duration of the diastolic murmur may be quite short due to rapid ventricular filling and early equilibration of aortic and left ventricular diastolic pressures. In one IRAD review, patients older than 70 years of age were significantly less likely to have a murmur of aortic regurgitation than younger patients (Black & Manning, 2021b).

Focal Neurologic Deficit

Focal neurologic deficits are due to propagation of the dissection proximally or distal to the initial tear involving branch arteries or due to mass effects as the expanding aorta compresses surrounding structures. Neurological symptoms, ranging from hoarseness to paraplegia and altered mental status, occur in 18% to 30% of patients with aortic dissection (Black & Manning, 2021a).

CVA or altered consciousness can be from direct extension of the dissection into the carotid arteries or diminished carotid blood flow. Alterations of consciousness are more common in women than in men.

Acute paraplegia is from spinal cord ischemia. Spinal cord ischemia from the interruption of intercostal vessels is more common with type B aortic dissections than with type A dissections. It may occur in 2% to 3% of all patients (Black & Manning, 2021b).

Horner syndrome is from compression of the superior cervical sympathetic ganglion. 

Hoarseness is from vocal cord paralysis due to compression of the left recurrent laryngeal nerve.

Hypotension

Syncope, hypotension, or shock at initial presentation are more common in patients with ascending aortic dissection, whereas hypertension is more common in descending aortic dissection (Black & Manning, 2021b). Hypotension/shock may be related to rupture of the aorta or propagation of the dissection via the following mechanisms:

  • Cardiac tamponade from rupture can lead to sudden death
    • Cardiac tamponade occurs more often in women than in men
  • Acute aortic valve regurgitation
  • Acute myocardial ischemia or MI due to coronary occlusion
    • The right coronary artery is most commonly involved and infrequently leads to complete heart block
  • Hemothorax or hemoperitoneum, and possibly exsanguination if the dissection extends through the adventitia in the thoracic or abdominal aorta

Syncope

According to one review, syncope accompanies 13% of dissections involving the ascending aorta (Black & Manning, 2021a). Syncope occurs in 5% to 10% of patients and often indicates the development of cardiac tamponade or involvement of the brachiocephalic vessels (Black & Manning, 2021b). Overall, patients in the IRAD study presenting with syncope were more likely to have a type A dissection than a type B dissection and more likely to have cardiac tamponade. Similarly, they were more likely to have a CVA and more likely to die in the hospital (Black & Manning, 2021b).

Although patients presenting with syncope had a higher rate of severe complications (tamponade, CVA, death), almost one-half of syncope patients had none of those, as mentioned earlier complications to explain their loss of consciousness (Black & Manning, 2021b).

Pulmonary Embolism (PE)

Acute PE is a form of venous thromboembolism (VTE) that is common and sometimes fatal. The clinical presentation of PE is variable and often nonspecific, making the diagnosis challenging. The evaluation of patients with suspected PE should be efficient to be diagnosed and therapy administered quickly to reduce the associated morbidity and mortality.

Definition

PE refers to obstruction of the pulmonary artery or one of its branches by material (e.g., thrombus, tumor, air, or fat) that originated elsewhere in the body. This topic review focuses upon PE due to thrombus.

Nomenclature

PE can be classified by the following:

Temporal Pattern

The temporal pattern of presentation (acute, subacute, or chronic) (Thompson & Kabrhel, 2020):

  • Acute:
    • Patients with acute PE typically develop signs and symptoms immediately after obstruction of pulmonary vessels.
  • Subacute:
    • Some patients with PE may also present subacutely within days or weeks following the initial event.
  • Chronic:
    • Patients with chronic PE slowly develop symptoms of pulmonary hypertension over many years (i.e., chronic thromboembolic pulmonary hypertension [CTEPH]).

Hemodynamic Stability

The presence or absence of hemodynamic stability (hemodynamically unstable or stable) (Thompson & Kabrhel, 2020):

  • Hemodynamically unstable PE is also called "massive" or "high-risk" PE. Hemodynamically unstable PE is that which results in hypotension which is defined as a systolic blood pressure <90 mmHg or a drop in systolic blood pressure of ≥40 mmHg from baseline for a period >15 minutes or hypotension that requires vasopressors or inotropic support and is not explained by other causes such as sepsis, arrhythmia, left ventricular dysfunction from acute myocardial ischemia or MI, or hypovolemia. Although hemodynamically unstable PE is often caused by large (i.e., massive) PE, it can sometimes be small in patients with underlying cardiopulmonary disease. Thus, the term "massive" PE does not necessarily describe the size of the PE as much as its hemodynamic effect (Thompson & Kabrhel, 2020).
  • Hemodynamically stable PE is defined as PE that does not meet the definition of hemodynamically unstable PE. Hemodynamically stable PE is called:
    • "Submassive" or "intermediate-risk" PE if there is associated right ventricular strain, OR
    • "Low-risk" PE if there is no evidence of right ventricular strain.

There is a spectrum of severity within this population ranging from patients who present with small, mildly symptomatic, or asymptomatic PE (also known as "low-risk PE") to those who present with mild or borderline hypotension that stabilizes in response to fluid therapy or those who present with right ventricle dysfunction (also known as "submassive" or "intermediate-risk" PE).

The distinction between hemodynamically stable and unstable PE is important because patients with hemodynamically unstable PE are more likely to die from obstructive shock (i.e., severe right ventricular failure). Importantly, death from hemodynamically unstable PE often occurs within the first two hours, and the risk remains elevated for up to 72 hours after presentation (Thompson & Kabrhel, 2020).

Anatomic Location

The anatomic location lends the names saddle, lobar, segmental, and subsegmental. Saddle PE lodges at the bifurcation of the main pulmonary artery, often extending into the right and left main pulmonary arteries. Approximately 3% to 6% of patients with PE present with a saddle embolus (Thompson & Kabrhel, 2020). Traditionally, saddle PE was thought to be associated with hemodynamic instability and death. However, retrospective studies suggest that among those diagnosed with a saddle embolus, only 22% are hemodynamically unstable, with an associated mortality of 5% (Thompson & Kabrhel, 2020).

A clot "in transit" through the heart is often classified as a form of PE, even though the thrombus has not yet lodged in a pulmonary artery. Clot-in-transit is associated with high mortality (up to 40%) (Thompson & Kabrhel, 2020).

Most PEs move beyond the bifurcation of the main pulmonary artery to lodge distally in the main, lobar, segmental, or subsegmental branches of a pulmonary artery. PE can be bilateral or unilateral, depending on whether they obstruct arteries in the right, left, or both lungs. Smaller thrombi located in the peripheral segmental or subsegmental branches are more likely to cause pulmonary infarction and pleuritis.

Symptomatic vs. Asymptomatic

The presence or absence of symptoms also categorizes the type of PE (Thompson & Kabrhel, 2020):

  • Symptomatic PE refers to the presence of symptoms that usually leads to radiologic confirmation of PE.
  • Asymptomatic PE refers to the incidental finding of PE on imaging (e.g., contrast-enhanced CT performed for another reason) in a patient without symptoms.

Epidemiology

The incidence of PE is estimated at over 1 in 1,000 patients, but the diagnosis is often missed, and the incidence may be higher (Hollander & Chase, 2021). Mortality rates vary widely based upon comorbid conditions and the size of the embolus. Early diagnosis and treatment reduce mortality for large hemodynamically unstable PE.

General Population

Estimates of the incidence of PE in the general population have increased following the introduction of D-dimer testing and CT pulmonary angiography (CTPA) in the 1990s (Thompson & Kabrhel, 2020). One database analysis reported a doubling in the incidence of PE from 62 cases per 100,000 in the five years before 1998 to 112 cases per 100,000 in the seven years after 1998 (Thompson & Kabrhel, 2020). Other studies have confirmed similarly increased rates over time.

The overall incidence is higher in males compared with females. The incidence rises with increasing age, particularly in women, such that PE has an incidence of >500 per 100,000 after the age of 75 years (Thompson & Kabrhel, 2020). The use of statins may reduce the incidence of PE.

In the U.S., PE accounts for approximately 100,000 annual deaths (Thompson & Kabrhel, 2020). However, many causes of sudden cardiac death are thought to be secondary to PE, so the actual mortality attributable to PE is difficult to estimate.

Deaths from diagnosed PE have been declining. Overall mortality from PE appears to be high. One study reported a 30-day and one-year mortality at 4% and 13%, respectively, and a case-fatality rate that increased with increasing age (Thompson & Kabrhel, 2020).

Age-adjusted mortality rates for African-American adults have been reported to be 50% higher than those for whites. Additionally, mortality rates for whites are 50% higher than those for other races (Asian, American Indian, etc.) (Thompson & Kabrhel, 2020).

Special Populations

  • Hospitalized gynecologic patients
  • Hospitalized medical patients
  • Hospitalized surgical patients
  • Patients with acute traumatic spinal cord injury
  • Patients who are pregnant
  • Patients with inherited thrombotic disorders
  • Patients with malignancy
  • Patients with nephrotic syndrome
  • Patients with stroke
  • Patients with total joint arthroplasty or replacement

Pathogenesis and Pathophysiology

PE occurs when a dislodged venous clot migrates through the right side of the heart and becomes lodged at the branch point of the pulmonary arteries (saddle embolus) or more distally. Occlusion of pulmonary blood flow results in pulmonary hypertension, right ventricular dysfunction, poor gas exchange, and ultimately parenchymal infarction (Hollander & Chase, 2021; Thompson & Kabrhel, 2020).

Pathogenesis

The pathogenesis of PE is similar to that which underlies the generation of thrombus (i.e., Virchow's triad). Virchow's triad consists of venous stasis, endothelial injury, and a hypercoagulable state.

DVT and Subsequent PE Risk Factors

Risk factors for PE alone confirm that they are similar to those for VTE in general. Risk factors can be classified as inherited (i.e., genetic) and acquired. Twenty to thirty genetic risk factors for VTE have been identified, including (Hollander & Chase, 2021; Thompson & Kabrhel, 2020):

  • Factor V Leiden (there is a hematologic predisposition for venous thrombosis formation)
  • Prothrombin gene mutation (20210-A)
  • Anatomic predisposition (e.g., thoracic outlet syndrome)

Acquired risk factors can be further sub-classified as provoking or non-provoking. Provoking risk factors include (Hollander & Chase, 2021; Thompson & Kabrhel, 2020):

  • Central venous catheterization
  • Patients with cancer, lung, or chronic heart disease
  • Patients with a personal or family history of hypercoagulability
  • Pregnancy
  • Recent history of prolonged immobilization
  • Long-distance travel
  • Recent surgery (particularly an orthopedic procedure of the lower extremity lasting more than 30 minutes)
  • Trauma
  • Use of certain hormonal contraceptives or chemotherapeutic agents that raise serum levels of estrogen and, to a lesser extent, progestin.

Non-provoking risk factors include:

  • Heavy cigarette smoking
  • Obesity

Source

Most emboli are thought to arise from lower extremity proximal veins (iliac, femoral, and popliteal), and more than 50% of patients with proximal DVT have concurrent PE at presentation (Hollander & Chase, 2021; Thompson & Kabrhel, 2020).

Calf vein DVT rarely embolizes to the lung, and two–thirds of calf vein thrombi resolve spontaneously after detection. However, if untreated, one-third of calf vein DVT extends into the proximal veins, where they have greater potential to embolize (Hollander & Chase, 2021; Thompson & Kabrhel, 2020).

PE can also arise from DVT in non-lower-extremity veins, including renal and upper extremity veins, although embolization from these veins is less common. Most thrombi develop at sites of decreased flow in the lower extremity veins, such as valve cusps or bifurcations. However, they may also originate in veins with the higher venous flow, including the inferior vena cava or the pelvic veins, and non-lower-extremity veins, including renal and upper extremity veins (Hollander & Chase, 2021; Thompson & Kabrhel, 2020).

Pathophysiologic Response

Pulmonary emboli are typically multiple, with the lower lobes being involved in the majority of cases. Once the thrombus lodges in the lung, a series of pathophysiologic responses can occur (Hollander & Chase, 2021; Thompson & Kabrhel, 2020):

  • Infarction:
    • In about 10% of patients, small thrombi lodge distally into the segmental and subsegmental vessels resulting in pulmonary infarction.
    • These patients are more likely to have pleuritic CP and hemoptysis, presumed to be due to an intense inflammatory response in the lung and adjacent visceral and parietal pleura.
  • Abnormal gas exchange:
    • Impaired gas exchange from PE is due to the following two mechanisms which cause hypoxemia:
      • Mechanical and functional obstruction of the vascular bed altering the ventilation to perfusion ratio.
      • Inflammation resulting in surfactant dysfunction and atelectasis, resulting in functional intrapulmonary shunting.
        • Inflammation is also thought to be responsible for stimulating respiratory drive resulting in hypocapnia and respiratory alkalosis.
        • Hypercapnia and acidosis are unusual in PE unless shock is present.
  • Cardiovascular compromise:
    • Hypotension from PE is due to diminished stroke volume and cardiac output.
    • In patients with PE, pulmonary vascular resistance (PVR) is increased due to physical obstruction of the vascular bed with thrombus and hypoxic vasoconstriction within the pulmonary arterial system. Increased PVR, in turn, impedes right ventricular outflow and causes right ventricular dilation and flattening or bowing of the intraventricular septum. Reduced flow from the right ventricle and right ventricular dilation reduces left ventricular preload, thereby compromising cardiac output.
      • For example, when obstruction of the pulmonary vascular bed approaches 75%, the right ventricle must generate a systolic pressure over 50 mmHg to preserve adequate pulmonary artery flow. When the right ventricle is unable to accomplish this, it fails, and hypotension ensues.
        • Thus, multiple large thrombi are generally responsible for hypotension in patients without the underlying cardiopulmonary disease via this mechanism.
        • In contrast, in patients with underlying cardiopulmonary disease, smaller emboli can induce hypotension, likely due to a substantial vasoconstrictive response and/or an inability of the right ventricle to generate sufficient pressure to combat high PVR.

History and Physical Examination

The most common symptoms in patients with PE were identified in the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) group. These symptoms include (Thompson et al., 2021):

  • Dyspnea at rest or with exertion (73%):
    • The onset of dyspnea is frequently (but not always) rapid, usually within seconds or minutes.
    • Dyspnea may be less frequent in older patients with no previous cardiopulmonary disease.
    • Dyspnea is more likely to be present in patients with PE in the main or lobar vessels.
  • Pleuritic pain (66%):
    • Approximately 10% of patients present with the symptoms of an infarcted lung, usually due to smaller, more peripheral emboli.
    • Pleuritic pain is typical in this population due to inflammation of the pleura.
  • Calf or thigh pain or swelling (44%)
  • Cough (37%)
  • Orthopnea (28%)
  • Wheezing (21%)
  • Hemoptysis (13%):
    • Hemorrhage from the infarcted lung is also thought to be responsible for hemoptysis.

Less common presentations include (Thompson et al., 2021):

  • Hemodynamic collapse (<10%)
  • Hoarseness from a dilated pulmonary artery (rare presentation) (Ortner syndrome)
  • Presyncope
  • Syncope:
    • Retrospective studies report syncope as the presenting symptom in 10% or less of cases.
      • Among those presenting with syncope, rates of PE ranging from 2% to 17% have been reported.
    • Syncope may indicate a high thrombus burden since up to two-thirds of patients with PE who present with syncope have large thrombi located in the mainstem or lobar arteries.
    • The reasons for syncope in patients with PE are poorly understood. Still, they may be partially explained by transient or persistent arrhythmias (e.g., atrial fibrillation) as thrombus travels through the heart or transient obstruction as the embolus transits the pulmonic valve.

Some patients have a delayed presentation over weeks or days. One prospective study reported that patients with a delayed presentation beyond one week tended to have larger, more centrally located PE than patients who presented within seven days (Thompson et al., 2021).

Signs and symptoms of PE may also evolve such that patients who initially present with mild symptoms may become increasingly symptomatic or hemodynamically unstable, sometimes very quickly (minutes to hours). The symptoms may be secondary to recurrent embolization or progressive pulmonary hypertension secondary to vasoconstriction. Similarly, as a pulmonary infarct evolves, patients may develop progressive dyspnea, hypoxemia, pleuritic pain, and hemoptysis. Importantly, symptoms may be mild or absent, even in large PE. Although the true incidence of asymptomatic PE is unknown, one systematic review of 28 studies found that one-third of the 5,233 patients who had a DVT also had asymptomatic PE (Thompson et al., 2021).

Common presenting signs on physical examination include (Thompson et al., 2021):

  • Tachypnea (54%)
  • Calf or thigh swelling, erythema, edema, tenderness, palpable cords (47%)
  • Tachycardia (24%)
  • Rales (18%)
  • Decreased breath sounds (17%)
  • An accentuated pulmonic component of the second heart sound (15%)
  • Jugular venous distension (14%)
  • Fever, mimicking pneumonia (3%)

Although upper extremity DVT (UEDVT) embolize less commonly than lower extremity DVT (LEDVT), symptoms of UEDVT (e.g., arm pain or tightness) should also raise the suspicion of PE (Thompson et al., 2021).

PE is a common cause of sudden cardiac arrest or circulatory collapse, especially among patients younger than 65 years old (Thompson et al., 2021). Among such patients, either dyspnea or tachypnea is present in 91% of cases. Massive PE may be accompanied by acute RV failure manifested by (Thompson et al., 2021):

  • Cyanosis
  • Increased jugular venous pressure
  • Obstructive shock
  • Parasternal lift
  • Right-sided third heart sound

Shock may also develop in patients with smaller PE who have severe underlying pulmonary hypertension. A transition from tachycardia to bradycardia or a narrow complex to a broad complex tachycardia (i.e., right bundle branch block) is an ominous sign of RV strain and impending shock (Thompson et al., 2021). PE should be suspected anytime there is hypotension accompanied by an elevated central venous pressure that is not otherwise explained by acute MI, tension pneumothorax, pericardial tamponade, or a new arrhythmia.

Tension Pneumothorax

A tension pneumothorax arises when the air in the pleural space builds up enough pressure to interfere with venous return, leading to hypotension, tachycardia, and severe dyspnea. Tension pneumothorax may be seen in approximately 1% to 2% of patients, likely higher in patients with trauma and patients receiving mechanical ventilation (Lee, 2021a). Patients receiving mechanical ventilation and who develop initial signs of pneumothorax are more likely to rapidly progress to cardiovascular collapse than those not on mechanical ventilation (Lee, 2021a).

Traditional teaching suggested that contralateral shift of the trachea and mediastinum, splaying of the ribs, and flattening of the ipsilateral diaphragm represent radiographic tension. However, these findings can be due to the elevated pleural pressure and do not necessarily indicate tension.

Clinical evidence of tachycardia, hypotension, and severe dyspnea indicates tension because these signs can be seen in patients without clinical evidence of tension (Lee, 2021a). Conversely, patients may have clinical evidence of tension in the absence of typical radiographic findings of tension. A one-way valve mechanism is responsible for tension pneumothorax allowing gas to enter the pleural space during inspiration but not exit fully during expiration. As gas accumulates, pressure increases within the ipsilateral pleural space resulting in hypotension from a reduced venous return, low cardiac output, and respiratory failure due to compression of the contralateral lung. Patients with these findings need immediate attention with needle or chest tube insertion.

Primary Spontaneous Pneumothorax (PSP)

Definition

A PSP is traditionally defined as a pneumothorax that presents without a precipitating external event in the absence of clinical lung disease (Lee, 2021a). Although PSP is not associated with known clinical lung disease (e.g., chronic obstructive pulmonary disease [COPD]), most affected patients have unrecognized lung abnormalities (mostly subpleural blebs) that likely predispose them to pneumothorax. However, following investigation, some patients with apparent PSP may have other more serious underlying lung diseases (e.g., Birt-Hogg-Dubé syndrome, thoracic endometriosis, lymphangioleiomyomatosis), thereby re-categorizing them as having secondary spontaneous pneumothorax (SSP). Thus, many experts believe that the distinction between pneumothorax in patients “without” lung disease (i.e., pneumothorax with subpleural blebs, also known as PSP) and pneumothorax in patients with lung diseases (i.e., SSP) is somewhat artificial and that PSP and SSP may exist on either end of a continuum.

Epidemiology

PSP is more common in men than women (roughly three to six times higher) (Lee, 2021b). The incidence of PSP in men ranges from 7.4 per 100,000 population per year in the U.S. The incidence of PSP in women ranges from 1.2 per 100,000 population per year in the U.S.

A hospital database study of ED visits from January 2008 to December 2014 reported that 79% of pneumothoraces were males and 21% in females (Lee, 2021b). The prevalence of asymptomatic PSP is unknown, but one retrospective study of Japanese students suggested that the rate may be as high as 0.042% and higher in men than women (Lee, 2021b). Mild collapse (i.e., <10% collapse) was present in approximately half of the individuals, most of whom underwent intervention.

Pathogenesis

PSP is thought to be due to small apical subpleural blebs or bullae (i.e., air sacs between the lung tissue and pleura) that rupture into the pleural cavity. The mechanism of bleb/bulla formation is unknown. However, since PSP classically occurs in tall, thin males between the ages of 10 and 30 years, the development of subpleural blebs is thought to be due to either increasing negative pressure or greater mechanical alveolar stretch at the apex of the lungs during growth or a congenital phenomenon in which lung tissue at the apex grows more quickly than the vasculature, thereby outstripping its blood supply (Lee, 2021a).

Pathologic assessment of resected specimens suggests disrupted areas of mesothelial cells, inflammation, and pores of 10 to 20 microns in diameter rather than a breach in the visceral pleural membrane. The leakage of fluorescein seen on autofluorescence thoracoscopy also supports this theory.

Risk Factors

Associated risk factors of tension pneumothoraxes include (Lee, 2021a):

Smoking (cigarette, cannabis):

Cigarette smoking (current or past) is a significant risk factor for PSP, probably due to airway inflammation and respiratory bronchiolitis.

In an analysis of four studies that included 505 patients with PSP, 91% were smokers (Lee, 2021a). Furthermore, the risk of PSP was directly related to the amount of cigarette smoking. Compared with nonsmokers, the relative risk of PSP in men was seven times higher in light smokers (1 to 12 cigarettes per day), 21 times higher in moderate smokers (13 to 22 cigarettes per day), and 102 times higher in heavy smokers (>22 cigarettes per day). The relative risk was 4, 14, and 68 times higher for women in light, moderate, and heavy smokers, respectively (Lee, 2021a). Similarly, patients with PSP who smoke cigarettes have more respiratory bronchiolitis and higher recurrence rates than those who do not smoke. Regularly smoking cannabis appears to increase the risk of PSP similarly.

Genetic Predisposition:

Reports have been published describing the clustering of PSP in certain families. Autosomal dominant, autosomal recessive, polygenic, and X-linked recessive inheritance mechanisms have all been proposed (Lee, 2021a).

Genetic variants associated with PSP include:

  • Alpha-1 antitrypsin (M1M2 mutations)
  • Fibrillin 1 (FBN1) mutations
  • Human leukocyte antigen (HLA) haplotype A2B40

The autosomal dominant Birt-Hogg-Dubé syndrome (BHD) due to mutations in the folliculin [FLCN] gene [especially c.1300G>C, c.250-2A>G], hyperhomocysteinemia, alpha-1 antitrypsin, and Marfan syndrome are also inherited conditions associated with pneumothorax that may masquerade as PSP when the diagnosis is not known. For example, one study reported that 5% to 10% of patients with PSP turned out to have BHD following an investigation (Lee, 2021a).

Several reports suggest that drops in atmospheric pressure may be associated with an increase in the incidence of pneumothorax. Activities such as SCUBA diving can precipitate a spontaneous pneumothorax, and air travel may precipitate recurrence in patients with an incompletely healed pneumothorax.

Secondary Spontaneous Pneumothorax (SSP)

Definition

SSP is defined as pneumothorax that presents as a complication of underlying lung disease. SSP has a male preponderance, but SSP presents in older patients (>55 years) in contrast with PSP. One large hospital database of admissions reported that the rate of admissions for SSP, 61% of which were due to chronic obstructive pulmonary disease (COPD), has increased by 9% over 48 years from 1968 through 2016 (Lee, 2021a). Rates were higher in males than females.

SSP occurs most frequently in patients with COPD, cystic fibrosis (CF), and asthma. Regardless of etiology, the accumulation of air in the pleural space can lead to tension pneumothorax with compression of the mediastinum, causing rapid clinical deterioration and death if unrecognized.

Nearly every lung disease can be complicated by SSP, although the most commonly associated diseases are COPD and Tuberculosis (TB) in endemic areas. In one study of hospital admissions, up to 80% of SSP cases were due to Emphysema/COPD or Interstitial lung disease (Lee, 2021a).

Other causes of SSP include:

  • CF
  • Necrotizing pneumonia
  • Primary or metastatic lung malignancy
  • Sarcoidosis

Pneumothorax typically presents as a complication of these common lung diseases and is rarely an initial manifestation. In contrast, pneumothorax may be the presenting feature of uncommon causes of SSP and the diagnosis may not be known upon presentation (e.g., lymphangioleiomyomatosis, BHD syndrome, etc.).

Risk Factors

COPD/Emphysema:

COPD is the most common cause of SSP, with 50% to 70% of SSP cases attributed to COPD in small case series. Rupture of apical blebs or bullae is the usual cause. Patients with COPD may also be at higher risk for iatrogenic pneumothorax (e.g., venous catheterization, mechanical ventilation), particularly when there is a significant amount of underlying emphysema or air trapping. The severity of COPD correlates with the likelihood of developing SSP (Lee, 2021a).

Cystic Fibrosis (CF):

Approximately 3% to 4% of patients with CF will have an episode of SSP during their lifetime, but in those who survive to age 18, the incidence is 16% to 20% (Lee, 2021a). CF-related SSP is usually due to the rupture of apical subpleural cysts. The risk of pneumothorax in CF increases with the severity of lung function abnormalities. Other than cysts and fibrosis, other factors that may predispose to the development of pneumothorax in CF, which may reflect disease severity rather than being independent risk factors, include (Lee, 2021a):

  • A prior episode of massive hemoptysis
  • Infection with Aspergillus species
  • Infection with Burkholderia cepacia complex
  • Infection with Pseudomonas aeruginosa
  • Noninvasive positive pressure
  • Possibly inhaled medications

Lung Malignancy:

Both primary and metastatic lung malignancy has been associated with SSP. Among 168 patients with SSP, malignancy was the underlying cause in 16% (Lee, 2021a). The underlying malignancy was more commonly a lung primary than metastatic disease. Potential mechanisms include tumor necrosis, endobronchial obstruction with air trapping, development of necrotizing cysts or pneumonia, and coexisting COPD/emphysema.

Less commonly, malignancies that metastasize to the lung are associated with the development of necrotic cysts, which can result in SSP. Examples include (Lee, 2021a):

  • Angiosarcoma
  • Gastrointestinal adenocarcinoma
  • Genitourinary adenocarcinoma
  • Lymphoma
  • Mesenchymal cystic hamartoma
  • Pleuropulmonary blastoma
  • Sarcoma

Necrotizing Lung Infections:

SSP can complicate the course of necrotizing pneumonia due to Pneumocystis jirovecii (i.e., pneumocystis pneumonitis [PCP]), TB, bacteria, and less often fungi or other microorganisms, including severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) (Lee, 2021a). The relative frequency of these etiologies depends upon the frequency of these diseases in the population studied. The presumed common mechanism underlying pneumothorax in patients with lung infection is direct invasion and necrosis of lung tissue, including the pleura by the microorganism itself.

Pneumocystis jirovecii:

Unilateral and bilateral SSP can be seen in patients with PCP, most often in human immune deficiency virus (HIV) patients. In the era of antiretroviral therapy (ART), the frequency of pneumothorax complicating PCP is approximately 5% to 10% (Lee, 2021a). However, another study reported lower rates, with pneumothorax complicating only 1.2% of all hospital admissions in a cohort of 599 HIV-infected patients. However, over half had non-pulmonary reasons for admission.

In patients with HIV-related PCP, it has been hypothesized that the administration of aerosolized pentamidine may increase the likelihood for PCP to grow and cause cavitation in the peripheral parts of the upper lobe, thereby increasing the risk for pneumothorax (Lee, 2021a). This phenomenon may relate to the preferential delivery of the aerosolized agent to the proximal parenchyma of the lower lobes rather than the upper lobes. Unlike bacterial pneumonia, pneumothorax associated with PCP is more likely to be bilateral than unilateral.

Bacterial Pneumonia:

SSP has been associated with bacterial pneumonia caused by Staphylococcus, Klebsiella, Pseudomonas, Streptococcus pneumoniae, and anaerobic organisms. Among 168 patients with SSP, bacterial pneumonia was the etiology in 11% of cases (Lee, 2021a). SSP in bacterial pneumonia is more likely to be unilateral than bilateral. It can be associated with an extension of bacterial infection into the pleura and the development of empyema, giving the appearance of a hydropneumothorax.

Tuberculosis (TB):

SSP occurs in 1% to 3% of patients hospitalized with pulmonary TB (Lee, 2021a). Rates are higher in endemic areas. The pneumothorax is usually due to the rupture of a tuberculous cavity into the pleural space.

Other pulmonary infections have been associated with pneumothorax, including fungal, viral, and mycobacterial infections other than TB.

Cystic Lung Disorders:

Pneumothorax is common in lung conditions associated with cysts. However, since many of these conditions are rare, pneumothorax in this setting may masquerade as PSP when the underlying diagnosis is unknown. Disorders associated with cysts include conditions such as (Lee, 2021a):

  • BHD syndrome
  • Diffuse Langerhans cell histiocytosis
  • Lymphangioleiomyomatosis
  • Lymphocytic interstitial pneumonitis (e.g., Sjögren syndrome)

Catamenial Pneumothorax:

Catamenial pneumothorax refers to a pneumothorax occurring in association with menses due to thoracic endometriosis. Young females with endometriosis may experience menses-related pneumothoraces if pleural involvement exists. CP or hemoptysis perimenstrually in a young woman with or without a history of endometriosis might suggest catamenial pneumothorax (Lee, 2021a). In this condition, pneumothorax is thought to relate to the development and involution of pleural implants comprised of endometrial tissue. Consequently, some experts consider this PSP since parenchymal lung disease is typically absent.

HIV:

Pneumothorax is seen in HIV due to several etiologies, particularly infections including (Lee, 2021a):

  • Bacterial pneumonia
  • Fungal, viral, and mycobacterial infections
  • PCP pneumonia
  • Pulmonary TB
  • Toxoplasmosis

Patients with HIV can also be at risk for iatrogenic pneumothorax and pneumothorax due to the presence of pneumatoceles (typically from old Staphylococcal or PCP infection), Kaposi sarcoma, intravenous drug abuse, and cigarette smoking. One report suggested that the degree of immunosuppression in HIV may affect the etiology of pneumothorax. In patients with CD4 positive lymphocyte counts >200 cells/mL, pneumothorax was more likely due to bacterial pneumonia, whereas pneumothorax was more often associated with those with counts <200 cells/mL Pneumocystis jirovecii (Lee, 2021a).

Architectural Abnormalities of the Pleural Membrane:

Pneumothorax may occur in conditions where the pleural membrane's integrity and parenchyma are abnormal, the diagnosis of which may or may not be known at the time of presentation. These include (Lee, 2021a):

  • Ehlers-Danlos syndrome
  • Homocystinuria
  • Marfan syndrome

In Marfan and Ehlers-Danlos syndrome, it is thought that abnormal elastin or collagen content of the pleural membrane and parenchyma may predispose patients to pneumothorax (Lee, 2021a). Why patients with homocystinuria develop pneumothorax is less clear, but homocysteine plays a role in vascular homeostasis and smooth muscle and collagen production regulation in the lung. Patients with Marfan syndrome may also develop parenchymal cysts that may increase the risk of developing a pneumothorax.

Other less common causes of SSP include:

  • Ankylosing spondylitis
  • Asthma
  • Granulomatous lung diseases (e.g., rheumatoid arthritis, granulomatosis with polyangiitis, and sarcoidosis)
  • Inhalation of cocaine
  • Interstitial lung disease (e.g., idiopathic pulmonary fibrosis, silicosis)
  • Several case series have also described pneumothorax occurring in patients with coronavirus disease 2019 (COVID-19) without noninvasive or invasive ventilation.

Other Types of Pneumothoraxes

Traumatic Pneumothorax

Pneumothorax is traumatic when due to blunt or, more commonly, penetrating thoracic trauma. Trauma is probably the most common cause of pneumothorax.

Traumatic pneumothorax can be categorized as iatrogenic or non-iatrogenic (Lee, 2021a):

Iatrogenic:

Pneumothorax is iatrogenic when induced by a medical procedure, typically procedures that can introduce air into the pleural space via the chest, neck, gut, or abdomen. These include:

  • Breast tissue expander placement
  • Chest acupuncture
  • Colonoscopy
  • Mechanical ventilation
  • Pacemaker insertion
  • Shoulder arthroscopy
  • Thoracentesis
  • Thoracic or esophageal procedures or surgery
  • Tracheostomy

Most commonly, iatrogenic pneumothorax is induced by lung procedures (e.g., percutaneous or transbronchial lung or mediastinal biopsy and fiducial seed placement for radiotherapy, thoracentesis) central venous catheterization.

The prevalence of iatrogenic pneumothorax is poorly studied but likely varies with operator experience, presence of risk factors such as underlying lung disease, and prevalence of procedures performed. In one study of over 12,000 procedures, the prevalence of pneumothorax was 1.4%, among which 57% were due to emergency procedures (Lee, 2021a).

The most frequent procedures associated with pneumothorax were central venous catheterization, thoracentesis, and barotrauma due to mechanical ventilation. Another study reported a higher incidence of iatrogenic pneumothorax in teaching compared with non-teaching hospitals (Lee, 2021a).

Non-Iatrogenic:

Non-iatrogenic pneumothorax due to external trauma may be minor or severe. It is also termed “open pneumothorax” when a penetrating traumatic chest wall defect is present, through which atmospheric air enters the pleural space during inspiration (i.e., "sucking wound") and exits during expiration, resulting in a mediastinal swing away from the affected side during inspiration and toward the affected side during expiration (“mediastinal flutter”) (Lee, 2021a).

Miscellaneous Types

Several rare case reports have described pneumothorax in association with the following (Lee, 2021a):

Anorexia Nervosa:

Patients with anorexia nervosa may develop spontaneous pneumothorax.

It is thought that the pulmonary parenchymal consequences of malnutrition (e.g., emphysema) contribute to the development of pneumothorax in these patients, but other unknown processes may be at play.

Exercise, Illicit Drug Use, Immunosuppressant Drugs:

Rare case reports and anecdotes suggest a possible relationship between pneumothorax and exercise, drug abuse (e.g., cocaine or heroin), or chemotherapeutic drugs (Lee, 2021a). It has been postulated that exercise and illicit drug use may cause pneumothorax, leading to deeper inhalation and Valsalva maneuvers. Some injection drug users may also develop traumatic pneumothorax from attempting to inject into the neck veins. A detailed drug history or track marks may suggest illicit drug use or identify immunosuppressant drugs not previously suspected as an etiology of pneumothorax.

Air Travel and Scuba Diving:

Pneumothorax may be associated with air travel and diving, although an underlying lung disorder may increase this risk further.

Clinical Presentation

Pneumothorax should be suspected in patients who present with acute dyspnea and CP (classically pleuritic), particularly in those with an underlying risk factor. Patients with pneumothorax classically present with the following (Lee, 2021a):

History

Pneumothorax most often presents with sudden onset of dyspnea and pleuritic CP. Since pneumothorax is usually unilateral, the pain is usually felt on the ipsilateral side but may be central or bilateral in rare cases when the pneumothorax is bilateral (Lee, 2021a).

The intensity of dyspnea can range from mild to severe. The severity of the symptoms primarily relates to the volume of air in the pleural space and the degree of pulmonary reserve, with dyspnea being more prominent if the pneumothorax is large or underlying disease is present.

Pneumothorax can present at all ages. Patients with primary spontaneous pneumothorax (PSP, i.e., associated with subpleural blebs in the absence of an underlying disorder) are typically in their early 20s (Lee, 2021a). PSP is rare after age 40 and classically occurs in young, tall, thin, smoking males. In contrast, since most cases of SSP (i.e., that associated with underlying lung disease) are due to emphysema, these patients tend to be older. However, this finding is not absolute. For example, pneumothorax in patients with lymphangioleiomyomatosis or thoracic endometriosis presents in young, non-smoking females of reproductive age.

Symptoms usually develop when the patient is at rest, although occasionally, pneumothorax develops during exercise, air travel, scuba diving, or illicit drug use. Alternatively, symptoms may occur during or following an invasive procedure or trauma to the chest, neck, gut, or abdomen.

A history of a risk factor or a disorder that can be complicated by pneumothorax may be present as well.

Physical Examination

In patients with a small pneumothorax, physical examination findings may not be evident or may be limited to signs of the underlying lung disease, if present. However, characteristic physical findings when a large pneumothorax is a present include (Lee, 2021a):

  • Absent tactile or vocal fremitus
  • Decreased chest excursion on the affected side
  • Diminished breath sounds
  • Enlarged hemithorax on the affected side
  • Hyper-resonant percussion
  • Subcutaneous emphysema (rare)

Characteristic physical findings of a sizeable pneumothorax or a pneumothorax in a patient with significant underlying lung disease include (Lee, 2021a):

  • Accessory muscle use
  • A history of hypercapnia
  • A pulse oxygen saturation <92%
  • Tachypnea

Tracheal deviation away from the affected side is a late sign but does not always indicate tension pneumothorax. Hemodynamic compromise (e.g., tachycardia, hypotension) is an ominous sign and suggests a tension pneumothorax or impending cardiopulmonary collapse. Some patients with mild or chronic pneumothorax may be asymptomatic and discovered incidentally.

A joint and skin examination may reveal (Lee, 2021a):

  • Dry eye and joint disease suggestive of Sjögren syndrome (which can be complicated by lung cysts)
  • Joint hypermobility or hyperextensible skin consistent with Ehlers Danlos syndrome
  • Pectus carinatum and disproportionate tall stature suggestive of Marfan syndrome

Pericardial (Cardiac) Tamponade

Pericardial tamponade (also called cardiac tamponade) occurs when there is an accumulation of pericardial fluid under pressure, leading to impaired cardiac filling (Hoit, 2021). Tamponade covers a spectrum of clinical severity. Some patients have mild compromise, while others develop a severe compromise in the cardiac filling, producing a picture resembling cardiogenic shock that requires an immediate reduction in pericardial pressure by pericardiocentesis.

The normal pericardium is a fibroelastic sac containing a thin layer of fluid that surrounds the heart. When larger amounts of fluid accumulate (pericardial effusion) or when the pericardium becomes scarred and inelastic, one of three pericardial compressive syndromes may occur (Hoit, 2021):

  • Cardiac Tamponade:
    • Cardiac tamponade, which may be acute or subacute, is characterized by the accumulation of pericardial fluid under pressure.
    • Variants include low pressure (occult) and regional cardiac tamponade.
  • Constrictive Pericarditis:
    • Constrictive pericarditis is the result of scarring and consequent loss of elasticity of the pericardial sac.
    • Pericardial constriction is typically chronic, but variants include subacute, transient, and occult constriction.
  • Effusive-Constrictive Pericarditis:
    • Effusive-constrictive pericarditis is characterized by underlying constrictive physiology with a coexisting pericardial effusion, usually with cardiac tamponade.
    • Such patients may be mistakenly thought to have only cardiac tamponade. However, the elevation of the right atrial and pulmonary wedge pressures after drainage of the pericardial fluid points to the underlying constrictive process.

In both cardiac tamponade and constrictive pericarditis, the cardiac filling is impeded by an external force. The normal pericardium can stretch to accommodate physiologic changes in cardiac volume. However, after its reserve volume is exceeded, the pericardium markedly stiffens. An important pathophysiologic feature of both cardiac tamponade and constrictive pericarditis is greatly enhanced ventricular interaction or interdependence. The hemodynamics of the left and right heart chambers are directly influenced by each other, much greater than normal.

Physiology

In cardiac tamponade, the primary abnormality is compression of all cardiac chambers due to increased pericardial pressure. The pericardium has some degree of elasticity, but once the elastic limit is reached, the heart must compete with the intrapericardial fluid for the fixed intrapericardial volume (Hoit, 2021).

As cardiac tamponade progresses, the cardiac chambers become smaller, and diastolic chamber compliance is reduced. The following consequences result from this constrained cardiac filling (Hoit, 2021):

Progressive Changes in Systemic Venous Return

  • Venous return is normally bimodal, with peaks during ventricular systole and early diastole.
  • The effusion produces compression throughout the cardiac cycle, with cardiac volume becoming minimal during ejection. Consequently, as cardiac tamponade becomes more severe, venous return is progressively shifted to systole as the peak associated with early diastolic filling diminishes.
  • When cardiac tamponade is very severe, the total venous return falls, the cardiac chambers shrink, and cardiac output and blood pressure fall.

Respiratory Variation in Venous Return

  • The inspiratory decline in thoracic pressure is transmitted through the pericardium to the right side of the heart and the pulmonary vasculature. Consequently, systemic venous return to the right heart increases with inspiration, and pulmonary venous return to the left heart decreases.
  • In cardiac tamponade, the rigid pericardium prevents the free wall from expanding. The ensuing distension of the right ventricle is limited to the interventricular septum, which along with relative underfilling of the left ventricle, causes the septum to bulge to the left, reducing left ventricular compliance and contributing to further decreased filling of the left ventricle during inspiration. This concept is referred to as "ventricular interaction" or "ventricular interdependence."
    • These changes will occur once pericardial pressure becomes substantially higher than ventricular diastolic pressures.
    • In less severe diseases, however, the degree to which they occur is related in part to the rate of pericardial fluid accumulation and pericardial compliance, both of which are related to the underlying cause.

Acute Bleeding

(e.g., trauma) into a relatively stiff pericardium can rapidly lead to cardiac tamponade.

  • As intrapericardial volume increases, an initial small increase in intrapericardial pressure is followed by an almost vertical ascent.

Chronic Accumulation

By comparison, chronic accumulation of a pericardial effusion (e.g., due to renal failure or malignancy) allows the pericardial compliance to increase gradually. As a result, intrapericardial pressure increases more slowly until a critical point is reached when an almost vertical ascent is again seen. In this setting, cardiac tamponade may not occur until two liters or more have accumulated. Very little fluid needs to accumulate to produce cardiac tamponade once the pericardium can no longer stretch. At this point, the initial removal of fluid during pericardiocentesis produces the largest reduction in intrapericardial pressure.

Etiology

The causes of cardiac tamponade include all of the causes of pericardial effusion or hemorrhage into the pericardium and iatrogenic etiologies.

Causes of pericardial disease include (Hoit, 2021):

  • Idiopathic (presumed to be viral, post-viral, or immune-mediated):
    • In most case series, most patients are not found to have an identifiable cause of pericardial disease. Frequently such cases are presumed to have a viral or autoimmune etiology.
  • Infectious:
    • Viral - Coxsackievirus, echovirus, adenovirus, Epstein-Barr virus, cytomegalovirus, influenza, varicella, rubella, HIV, hepatitis B, mumps, parvovirus B19, vaccina (smallpox vaccine)
    • Bacterial - Mycobacterium tuberculosis (most common cause in countries where TB is endemic), Staphylococcus, Streptococcus, Haemophilus, Neisseria (N. gonorrhoeae or N. meningitidis), Chlamydia (C. psittaci or C. trachomatis), Legionella, Salmonella, Borrelia burgdorferi (the cause of Lyme disease), Mycoplasma, Actinomyces, Nocardia, Tropheryma whippelii, Treponema, Rickettsia
    • Fungal - Histoplasma, Aspergillus, Blastomyces, Coccidioides, Candida
    • Parasitic - Echinococcus, amebic, Toxoplasma
    • Infective endocarditis with valve ring abscess
  • Noninfectious:
    • Autoimmune and autoinflammatory
      • Systemic inflammatory diseases, especially lupus, rheumatoid arthritis, scleroderma, Sjögren syndrome, vasculitis, mixed connective disease
      • Autoinflammatory diseases (especially familial Mediterranean fever and tumor necrosis factor associated periodic syndrome [TRAPS], IgG4-related disease)
      • Postcardiac injury syndromes (immune-mediated after cardiac trauma in predisposed individuals)
      • Others - Granulomatosis with polyangiitis (Wegener's), polyarteritis nodosa, sarcoidosis, inflammatory bowel disease (Crohn's, ulcerative colitis), Whipple's, giant cell arteritis, Behçet syndrome, rheumatic fever
  • Neoplasm:
    • Metastatic - Lung or breast cancer, Hodgkin's disease, leukemia, melanoma
    • Primary - Rhabdomyosarcoma, teratoma, fibroma, lipoma, leiomyoma, angioma
    • Paraneoplastic
  • Cardiac:
    • Early infarction pericarditis
    • Late postcardiac injury syndrome (Dressler's syndrome), also seen in other settings (e.g., post-MI and post-cardiac surgery)
    • Myocarditis
    • Dissecting aortic aneurysm
  • Trauma:
    • Blunt
    • Penetrating
    • Iatrogenic
      • Catheter and pacemaker perforations, cardiopulmonary resuscitation, post-thoracic surgery
  • Metabolic:
    • Hypothyroidism
      • Primarily pericardial effusion
    • Uremia
    • Ovarian hyperstimulation syndrome
  • Radiation
  • Drugs (rare)
    • Procainamide, isoniazid, or hydralazine as part of drug-induced lupus
    • Other drugs:
      • Cromolyn sodium, dantrolene, methysergide, anticoagulants, thrombolytics, phenytoin, penicillin, phenylbutazone, doxorubicin

Clinical Presentation

The presentation of patients with cardiac tamponade largely depends on the length of time pericardial fluid accumulates and the clinical situation (Hoit, 2021):

Acute Cardiac Tamponade

Occurs within minutes due to (Hoit, 2021):

  • Complications of an invasive diagnostic or therapeutic procedure
    • Rupture of the heart or aorta
    • Trauma

Acute cardiac tamponade generally results in a picture resembling cardiogenic shock requiring urgent pericardial pressure. Acute cardiac tamponade is sudden in onset, may be associated with CP, tachypnea, and dyspnea, and is life-threatening if not promptly treated. The jugular venous pressure is markedly elevated and may be associated with venous distension in the forehead and scalp. The heart sounds are often muted.

Hypotension is common due to the decline in cardiac output. Patients in cardiogenic shock typically have (Hoit, 2021):

  • Cool extremities
  • Decreased urine output
  • Peripheral cyanosis

Subacute Cardiac Tamponade

Usually is a less dramatic process than acute cardiac tamponade. Subacute cardiac tamponade occurs over days to weeks and can be associated with neoplastic, uremic, or idiopathic pericarditis (Hoit, 2021). Patients may be asymptomatic early in the course, but once intrapericardial pressure reaches a critical value, they complain of (Hoit, 2021):

  • Chest discomfort or fullness
  • Dyspnea
  • Fatigability
  • Peripheral edema

The physical examination in subacute severe cardiac tamponade may reveal hypotension with narrow pulse pressure, reflecting the limited stroke volume. However, patients with preexisting HTN may remain hypertensive due to increased sympathetic activity in the setting of cardiac tamponade.

Low Pressure (Occult) Cardiac Tamponade

Low pressure (occult) cardiac tamponade is a subset of subacute cardiac tamponade and occurs in severely hypovolemic patients. Patients who are severely hypovolemic because of traumatic hemorrhage, hemodialysis, or ultrafiltration, or over diuresis at presentation may have a low-pressure cardiac tamponade in which the intracardiac and pericardial are present diastolic pressures are low (Hoit, 2021).

The hemodynamic significance of these effusions can be demonstrated on echocardiography by right heart chamber collapse and respiratory variations in transvalvular flows. A fluid challenge with a rapid infusion of one liter of isotonic saline in the catheterization laboratory will usually elicit typical cardiac tamponade hemodynamics. Clinical findings commonly associated with cardiac tamponade (e.g., tachycardia, jugular venous distention, and pulsus paradoxus) were significantly less common in low-pressure cardiac tamponade than in classic cardiac tamponade.

Regional Cardiac Tamponade

Regional cardiac tamponade occurs when a loculated, eccentric effusion or localized hematoma produces regional cardiac tamponade in which only selected chambers are compressed (Hoit, 2021). Consequently, the typical physical, hemodynamic, and echocardiographic signs of cardiac tamponade, including pulsus paradoxus, diastolic pressure equalization, and chamber compression in standard apical and parasternal views, may be absent or attenuated.

Regional cardiac tamponade is most often seen after pericardiotomy or MI. Clinical suspicion should be heightened in these settings. Establishing the diagnosis is challenging and may require additional echocardiographic views (e.g., subcostal or transesophageal) and other advanced imaging techniques (e.g., computed tomography) (Hoit, 2021).

Physical Findings

Several findings may be present on physical examination, depending upon the type and severity of cardiac tamponade. However, none of the findings alone are highly sensitive or specific for the diagnosis. The findings associated with Beck's triad, namely low arterial blood pressure, dilated neck veins, and muffled heart sounds, are present in only a minority of cases of acute cardiac tamponade. Physical findings such as sinus tachycardia, even in the absence of frank hypotension, may indicate significant hemodynamic compromise from cardiac tamponade and serve as an indication for immediate pericardiocentesis. In contrast, Kussmaul's sign (the absence of an inspiratory decline in jugular venous pressure) is not usually seen in cardiac tamponade (Hoit, 2021).

Tachycardia and hypotension:

  • Patients with cardiac tamponade have impaired hemodynamics due to the external compression on the myocardium and the resulting impaired cardiac filling.
  • Sinus tachycardia is seen in almost all patients, allowing for at least partial maintenance of cardiac output, while hypotension is somewhat more variably present.
    • One exception is when the underlying disease is associated with bradycardia, pericardial effusion, and subacute cardiac tamponade associated with hypothyroidism.
  • Tachycardia may also not be seen in patients with early cardiac tamponade even though they have signs of a hemodynamically significant effusion, such as an elevated jugular venous pressure (Hoit, 2021).

Elevated jugular venous pressure:

  • The jugular venous pressure is almost always elevated in cardiac tamponade and may be associated with venous distension in the forehead and scalp.

Pulsus paradoxus:

  • Pulsus paradoxus, defined as an abnormally large decrease in systolic blood pressure (>10 mmHg) on inspiration, is a common finding in moderate to severe cardiac tamponade and is the direct consequence of ventricular interdependence.
  • The limitation on outward expansion of the right ventricle as blood flows in during inspiration, along with relative underfilling of the left ventricle, results in bulging of the interventricular septum into the left ventricle.
  • Both the bulging of the interventricular septum and the reduction in left ventricular filling contributes to a large stroke volume decrease.
  • However, not all patients with cardiac tamponade have pulsus paradoxus (e.g., those with chronic hypertension leading to elevated ventricular diastolic pressures or those with a co-existent atrial septal defect).

Pericardial rub:

  • A pericardial rub may be heard in patients with cardiac tamponade due to inflammatory pericarditis.

The clinical diagnosis is usually suspected based on the history and physical examination findings, which may include (Hoit, 2021):

  • CP
  • Dyspnea and tachypnea
  • Elevated jugular venous pressure
  • Hypotension
  • Peripheral edema
  • Pulsus paradoxus
  • Syncope or presyncope
  • Tachycardia

Differential Diagnosis

Acute cardiac tamponade, in which patients typically present with elevated JVP and hypotension, must be distinguished from (Hoit, 2021):

  • Acute MI (especially with right ventricular involvement):
    • It is associated with characteristic ECG changes of infarction.
  • Hemodynamically significant PE:
    • PE can cause dyspnea, hypotension, and even elevated JVP, but not pulsus paradoxus.
  • Aortic dissection:
    • In the absence of cardiac tamponade, aortic dissection should not cause an increase in JVP.
  • None of these disorders is associated with pulsus paradoxus.

Subacute cardiac tamponade, in which patients typically present with dyspnea, fatigue, elevated JVP, and edema, must also be distinguished from (Hoit, 2021):

  • Constrictive pericarditis
  • Congestive heart failure
  • Advanced liver disease with cirrhosis

Esophageal Rupture or Boerhaave Syndrome Leading to Mediastinitis

Effort rupture of the esophagus, or Boerhaave Syndrome, is a spontaneous perforation of the esophagus that results from a sudden increase in intraesophageal pressure combined with negative intrathoracic pressure (e.g., severe straining or vomiting) (Triadafilopoulos, 2020). Boerhaave syndrome is associated with high morbidity and mortality and is fatal in the absence of therapy. The occasionally nonspecific nature of the symptoms may contribute to a delay in diagnosis and a poor outcome. Mortality for patients with mediastinitis remains high (14% to 42%), even when treated with operative debridement and antibiotics.) Delays in diagnosis further increase mortality (Triadafilopoulos, 2020).

Review of the Esophagus

The esophagus is the organ through which food passes, aided by peristaltic contractions, from the pharynx to the stomach (Triadafilopoulos, 2020). The esophagus is a fibromuscular tube, about 10 inches long in adults, which travels behind the trachea and heart, passes through the diaphragm, and empties into the uppermost region of the stomach. During swallowing, the epiglottis tilts backward to prevent food from going down the larynx and lungs.

The esophagus is one of the upper parts of the digestive system. There are taste buds on its upper part. It begins at the back of the mouth, passing downwards through the rear part of the mediastinum, through the diaphragm, and into the stomach. In humans, the esophagus generally starts around the level of the sixth cervical vertebra behind the cricoid cartilage of the trachea, enters the diaphragm at about the level of the tenth thoracic vertebra, and ends at the cardia of the stomach, at the level of the eleventh thoracic vertebra (Triadafilopoulos, 2020).

Many blood vessels serve the esophagus, with blood supply varying along its course. The upper parts of the esophagus and the upper esophageal sphincter receive blood from the inferior thyroid artery, the parts of the esophagus in the thorax from the bronchial arteries and branches directly from the thoracic aorta, and the lower parts of the esophagus and the lower esophageal sphincter receive blood from the left gastric artery and the left inferior phrenic artery. The venous drainage also differs along the course of the esophagus. The upper and middle parts of the esophagus drain into the azygos and hemiazygos veins, and blood from the lower part drains into the left gastric vein. All these veins drain into the superior vena cava, except for the left gastric vein, a branch of the portal vein. Lymphatically, the upper third of the esophagus drains into the deep cervical lymph nodes, the middle into the superior and posterior mediastinal lymph nodes, and the lower esophagus into the gastric and celiac lymph nodes. Esophageal drainage is similar to the abdominal structures' lymphatic drainage that arises from the foregut, which all drain into the celiac nodes.

The upper esophagus lies at the back of the mediastinum behind the trachea, adjoining along the tracheoesophageal stripe, and in front of the erector spinae muscles and the vertebral column. The lower esophagus lies behind the heart and curves in front of the thoracic aorta. From the bifurcation of the trachea downwards, the esophagus passes behind the right pulmonary artery, left main bronchus, and left atrium. At this point, it passes through the diaphragm.

The thoracic duct, which drains most of the body's lymph, passes behind the esophagus, curving from lying behind the esophagus on the right in the lower part of the esophagus to lying behind the esophagus on the left in the upper esophagus. The esophagus also lies in front of parts of the hemiazygos veins and the intercostal veins on the right side. The vagus nerve divides and covers the esophagus in a plexus.

Review of the Mediastinum

The mediastinum is the central compartment of the thoracic cavity surrounded by loose connective tissue, as an undelineated region that contains a group of structures within the thorax (Triadafilopoulos, 2020). The mediastinum contains the heart and its vessels, the esophagus, the trachea, the phrenic and cardiac nerves, the thoracic duct, the thymus, and the lymph nodes of the central chest.

The mediastinum lies within the thorax and is enclosed on the right and left by pleurae. It is surrounded by the chest wall in front, the lungs to the sides, and the spine at the back. It extends from the sternum in front to the vertebral column behind. It contains all the organs of the thorax except the lungs. It is continuous with the loose connective tissue of the neck (Triadafilopoulos, 2020).

Figure 2: Mediastinum

Figure 2: Mediastinum

Epidemiology

Esophageal perforations are rare, with an incidence of 3.1 per 1,000,000 per year (Triadafilopoulos, 2020). Among esophageal perforations, approximately 15% are spontaneous perforations.

Etiology and Pathogenesis

Boerhaave syndrome usually occurs in patients with a normal underlying esophagus. However, a subset of patients with Boerhaave syndrome have (Triadafilopoulos, 2020):

  • Barrett's or infectious ulcers
  • Medication-induced esophagitis
  • Underlying eosinophilic esophagitis

A sudden increase in intraesophageal pressure combined with negative intrathoracic pressure results in a longitudinal esophageal perforation such as that associated with (Triadafilopoulos, 2020):

  • Childbirth
  • Prolonged coughing
  • Prolonged laughing
  • Seizure
  • Severe straining or vomiting (most frequent)
  • Weightlifting

The esophageal perforation usually involves the left posterolateral aspect of the distal intrathoracic esophagus and extends several centimeters. However, the rupture can occur in the cervical or intra-abdominal esophagus.

Rupture of the intrathoracic esophagus results in contamination of the mediastinal cavity with gastric contents. This rupture leads to chemical mediastinitis with mediastinal emphysema and inflammation and subsequently bacterial infection and mediastinal necrosis (Triadafilopoulos, 2020). Rupture of the overlying pleura by mediastinal inflammation or initial perforation directly contaminates the pleural cavity and pleural effusion results.

Although pericardial tamponade and infected pericardial effusions due to Boerhaave syndrome have been reported, they are rare. If untreated, sepsis and organ failure result.

Effort rupture of the cervical esophagus leads to a localized cervical perforation and has a more benign course. The spread of contamination to the mediastinum through the retro esophageal space is slow and attachments of the esophagus to the prevertebral fascia limit the lateral dissemination of esophageal flora.

Clinical Manifestations

The clinical features of Boerhaave syndrome depend upon the (Triadafilopoulos, 2020):

  • Degree of leakage
  • Location of the perforation (cervical, intrathoracic, or intra-abdominal)
  • Time elapsed since the injury occurred

Patients with Boerhaave syndrome often present with excruciating retrosternal CP due to an intrathoracic esophageal perforation.

Although a history of severe retching and vomiting preceding the onset of pain has classically been associated with Boerhaave syndrome, approximately 25% to 45% of patients have no history of vomiting (Triadafilopoulos, 2020).

Patients may have crepitus on palpation of the chest wall due to subcutaneous emphysema. In patients with mediastinal emphysema, mediastinal crackling with each heartbeat may be heard on auscultation, especially if the patient is in the left lateral decubitus position (Hamman's sign) (Triadafilopoulos, 2020). These signs, however, require at least an hour to develop after an esophageal perforation and, even then, are present in only a small proportion of patients.

Within hours of the perforation, patients can develop (Triadafilopoulos, 2020):

  • Cyanosis
  • Dyspnea
  • Fever
  • Hypotension
  • Odynophagia
  • Pleural effusion
  • Sepsis
  • Tachycardia
  • Tachypnea

Patients with cervical perforations can present with (Triadafilopoulos, 2020):

  • Crepitation due to the presence of cervical subcutaneous emphysema
  • Dysphagia
  • Dysphonia
  • Neck pain
  • Tenderness to palpation of the sternocleidomastoid muscle

Patients with an intra-abdominal perforation often report epigastric pain that may radiate to the shoulder, back pain, and an inability to lie supine. They may also present with an acute (surgical) abdomen. As with intrathoracic perforation, sepsis may rapidly develop within hours of presentation.

Diagnosis

Boerhaave syndrome is often diagnosed incidentally in a patient being evaluated for CP. The diagnosis of Boerhaave syndrome should be suspected in patients with severe chest, neck, or upper abdominal pain after an episode of severe retching and vomiting or other causes of increased intrathoracic pressure and the presence of subcutaneous emphysema on physical examination (Triadafilopoulos, 2020). While thoracic and cervical radiography can support the diagnosis, the diagnosis is established by contrast esophagram or CT scan. Delay in the diagnosis is associated with a higher risk of complications and mortality, ranging between 16% and 51% (Triadafilopoulos, 2020).

Differential Diagnosis

Acute onset of CP or abdominal pain may also be seen with disorders such as (Triadafilopoulos, 2020):

  • Dissecting aortic aneurysm
  • MI
  • Pancreatitis
  • Peptic ulcer perforation
  • Pneumonia
  • Spontaneous pneumothorax

Patients with Mallory-Weiss syndrome may have a history of forceful retching and epigastric or back pain, but hematemesis is the major clinical manifestation. Patients with Mallory-Weiss syndrome have longitudinal mucosal lacerations in the distal esophagus and proximal stomach and not a rupture of the esophagus, as seen in patients with Boerhaave syndrome. Therefore, patients with Mallory-Weiss syndrome do not have evidence of subcutaneous, mediastinal, or peritoneal air on x-rays or extravasation of esophageal contrast on barium esophagram/CT scan (Triadafilopoulos, 2020).

Exclusion of Underlying Esophageal Pathology

A subset of patients with Boerhaave syndrome may have underlying esophageal disorders (e.g., eosinophilic esophagitis, Barrett's ulcers) (Triadafilopoulos, 2020). Upper endoscopy with esophageal biopsies should be performed to evaluate the esophagus upon recovery.

Case Study

Patient: John Williams

Chief Complaint:

Mrs. Williams, your neighbor, asks you to come over to see her 18-year-old son, John, who is not feeling well since his return from Australia the previous evening. She states that he has been having right-sided chest pain, non-radiating, and difficulty breathing. His right leg is also swollen. John stated that he experienced a sudden onset of severe bilateral, non-radiating chest pain while on the plane but that now his pain is dull and achy, especially when he takes a deep breath. He stated that his right calf had started to become swollen two days before flying out of Sydney, Australia. He does not know if he has had a fever, but he has felt sweaty and cold.

Health History:

  • Smokes cigarettes (1ppd x 1 year)
  • He states he is 5 feet 8 inches tall and weighs 210 pounds

Past Medical History:

  • None

Past Surgical History:

  • T@A: 2008

Family History:

  • HTN (both mother and father)
  • Factor V Leiden (diagnosed in sister) but he has never been tested

Current Medications:

  • None

Travel History:

  • Returned from Sydney, Australia, after a two-week stay with friends. The plane travel took 18 hours to return to the United States.
  • Sydney, Australia, is currently experiencing an outbreak of COVID-19 variant D and going into lockdown, and that is why he returned early.

Physical Examination:

  • John is sitting upright in a lazy-boy chair
  • PERRLA, EOMs intact
  • MAE’s
  • RR: 40 at rest
  • HR: 150 regular regularities
  • Cough: productive of blood-tinged mucous
  • Wheezing: audible
  • Right calf: swollen, reddened, tender to light touch
  • Skin cool and clammy upon palpation

Interventions:

  • Phoned 911 and identified chief complaint
  • Stayed with John and his mother until EMS arrived

Discussion of Outcomes:

  • John Williams was transported to the local ED and is now awaiting laboratory and diagnostic tests.
  • Tentative diagnoses: PE.

Strengths and Weakness of the Approach Used in this Case:

  • John Williams’s initial health history and cursory physical examination were performed quickly at his home identifying risk factors.
  • Appropriate interventions initiated.

Summary and Recommendations

Patients presenting with CP or other symptoms (e.g., dyspnea, etc.) should be rapidly evaluated to determine if their symptoms suggest acute ischemia or some other potentially life-threatening illness. Use the OPQRST mnemonic.

Initial assessment and interventions for any patient complaining of CP should include:

  • Airway, breathing, and circulation assessed
  • Preliminary health history and physical examination obtained
  • 12-lead ECG performed
  • Resuscitation equipment brought to the bedside
  • A cardiac monitor attached to a patient
  • Oxygen is given as necessary
  • Intravenous (IV) access and blood work (including high-sensitivity troponin, if available) obtained
  • Initial history and physical examination:
    • Obtain a brief history including:
      • Associated symptoms
      • Characteristics of the pain
      • Confirmation of the presenting symptoms
      • Exacerbating and alleviating factors
      • History of or risk factors for cardiovascular disease
      • Potential contraindications to thrombolytic therapy
    • The history should address other potentially life-threatening, noncardiac causes of CP, such as:
      • Acute aortic dissection
      • Esophageal rupture
      • Perforating peptic ulcer
      • PE
      • Tension pneumothorax
    • The physical examination should include:
      • Assessment of hemodynamic status
      • Screening neurologic examination, especially if thrombolysis is entertained as a potential therapy

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References

  • Black, J., & Manning, W. (2021a). Clinical features and diagnosis of acute aortic dissection. UpToDate. Retrieved June 1st, 2021. Visit Source.
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