Pericardial Disease for USMLE Step 2
Pericardial Disease for the USMLE Step 2 Exam
Types of Pericardial Disease
Pericardial disease includes acute pericarditis, pericardial effusion, cardiac tamponade, and constrictive pericarditis, each with distinct features and treatments.
Acute Pericarditis
- Etiology:
- Infectious: Most commonly viral (e.g., Coxsackievirus), but also bacterial (e.g., tuberculosis) and fungal.
- Non-infectious: Causes include autoimmune diseases (e.g., lupus), post-myocardial infarction (Dressler syndrome), uremia, neoplasms, radiation, and certain medications.
- Clinical Presentation:
- Chest Pain: Sharp, pleuritic, and improves with sitting forward.
- Pericardial Friction Rub: Classic exam finding, best heard at the left sternal border.
- Fever: Often present, particularly with infectious or autoimmune causes.
- Diagnosis:
- ECG: Diffuse ST-segment elevation and PR-segment depression.
- Blood Tests: Elevated ESR, CRP, and possible mild elevation in cardiac biomarkers.
- Echocardiogram: Often normal, though a small effusion may be present.
- Management:
- NSAIDs or Aspirin: First-line treatment for symptom relief.
- Colchicine: Added to reduce recurrence risk.
- Glucocorticoids: Reserved for refractory cases or when NSAIDs are contraindicated, though they can increase recurrence risk.
Pericardial Effusion
- Etiology:
- Often due to underlying pericarditis, hypothyroidism, malignancy, trauma, or recent surgery.
- Effusions can vary in composition (e.g., serous, hemorrhagic, purulent).
- Clinical Presentation:
- Dyspnea and chest discomfort; if large, may compress nearby structures, causing dysphagia or hoarseness.
- May be asymptomatic if the effusion develops gradually.
- Diagnosis:
- Echocardiogram: Key diagnostic tool, quantifying effusion size and monitoring for tamponade.
- ECG: Low voltage QRS complexes and electrical alternans if a large effusion is present.
- Chest X-Ray: May show an enlarged cardiac silhouette if the effusion is large.
- Management:
- Observation: For small, asymptomatic effusions.
- Pericardiocentesis: For large, symptomatic effusions or if tamponade is suspected.
Cardiac Tamponade
- Pathophysiology: Rapid accumulation of fluid in the pericardium increases intrapericardial pressure, restricting ventricular filling, reducing stroke volume and cardiac output, and potentially leading to circulatory collapse.
- Clinical Presentation:
- Beck’s Triad: Hypotension, distended neck veins, and muffled heart sounds.
- Pulsus Paradoxus: Decrease in systolic blood pressure >10 mm Hg during inspiration.
- Symptoms: Dyspnea, tachycardia, and fatigue due to reduced cardiac output.
- Diagnosis:
- Echocardiogram: Essential for diagnosis; shows diastolic collapse of the right atrium and ventricle.
- ECG: May show low voltage QRS complexes and electrical alternans.
- Right Heart Catheterization: Shows equalization of pressures across all chambers, though rarely needed in acute cases.
- Management:
- Urgent Pericardiocentesis: Immediate drainage is necessary to relieve tamponade.
- Volume Expansion: Temporary measure to improve cardiac output if pericardiocentesis is delayed.
Constrictive Pericarditis
- Pathophysiology: Chronic inflammation leads to fibrosis and thickening of the pericardium, restricting diastolic filling and mimicking heart failure.
- Clinical Presentation:
- Right Heart Failure Symptoms: Peripheral edema, ascites, and hepatomegaly.
- Kussmaul’s Sign: Paradoxical rise in jugular venous pressure on inspiration.
- Pericardial Knock: An early diastolic sound from abrupt cessation of ventricular filling.
- Diagnosis:
- Echocardiography: Shows septal bounce and pericardial thickening.
- CT or MRI: Useful for identifying pericardial thickening and calcification.
- Right Heart Catheterization: Displays the “square root” sign in ventricular pressure tracings.
- Management:
- Diuretics: Used initially to manage volume overload.
- Pericardiectomy: Surgical removal of the pericardium is definitive for symptomatic relief in refractory cases.
Key Points
- Acute Pericarditis:
- Presents with sharp, pleuritic chest pain relieved by leaning forward.
- ECG shows diffuse ST elevation and PR depression; treated with NSAIDs, colchicine, and corticosteroids if refractory.
- Pericardial Effusion:
- May be asymptomatic or cause dyspnea; echocardiography is the gold standard.
- Observation is appropriate for small effusions; pericardiocentesis is required if tamponade is suspected.
- Cardiac Tamponade:
- Presents with Beck’s triad and pulsus paradoxus; requires urgent pericardiocentesis.
- Constrictive Pericarditis:
- Presents with signs of right heart failure, Kussmaul’s sign, and pericardial knock.
- Managed initially with diuretics; pericardiectomy is definitive in advanced cases.