Pericardial Disease for USMLE Step 3
Pericardial Disease for the USMLE Step 3 Exam
Types of Pericardial Disease
Pericardial disease includes acute pericarditis, pericardial effusion, cardiac tamponade, and constrictive pericarditis. Each has distinct pathophysiology, clinical presentations, and management strategies.
Acute Pericarditis
- Etiology:
- Infectious: Viral (most common, e.g., Coxsackievirus), bacterial (e.g., tuberculosis).
- Non-infectious: Autoimmune (e.g., lupus), post-myocardial infarction (Dressler syndrome), uremia, malignancy, and medications (e.g., procainamide, hydralazine).
- Clinical Presentation:
- Chest Pain: Sharp, pleuritic, often improving with sitting up and leaning forward.
- Pericardial Friction Rub: Classic finding, best heard at the left sternal border.
- Fever: Common, particularly in infectious or autoimmune cases.
- Diagnosis:
- ECG: Diffuse ST-segment elevations and PR-segment depressions.
- Blood Tests: Elevated ESR, CRP; cardiac biomarkers may be mildly elevated.
- Echocardiogram: Often normal or shows a small effusion.
- Management:
- NSAIDs or Aspirin: First-line therapy for symptom relief.
- Colchicine: Added to NSAIDs to reduce recurrence risk.
- Glucocorticoids: Reserved for refractory cases or contraindications to NSAIDs; increases recurrence risk.
Pericardial Effusion
- Etiology:
- Often occurs with pericarditis, but may also result from hypothyroidism, malignancy, trauma, or surgery.
- Clinical Presentation:
- Dyspnea and chest discomfort are common; large effusions may compress adjacent structures, causing dysphagia or hoarseness.
- May be asymptomatic if effusion accumulates slowly.
- Diagnosis:
- Echocardiogram: Diagnostic gold standard; quantifies effusion size and evaluates for tamponade.
- ECG: Low voltage QRS complexes; electrical alternans may appear with large effusions.
- Chest X-Ray: Enlarged cardiac silhouette if the effusion is large.
- Management:
- Observation: Small, asymptomatic effusions.
- Pericardiocentesis: Indicated for symptomatic or large effusions, or if tamponade is suspected.
Cardiac Tamponade
- Pathophysiology: Rapid accumulation of pericardial fluid restricts ventricular filling, leading to decreased stroke volume and cardiac output.
- Clinical Presentation:
- Beck’s Triad: Hypotension, distended neck veins, muffled heart sounds.
- Pulsus Paradoxus: Systolic blood pressure decreases by >10 mm Hg during inspiration.
- Symptoms: Dyspnea, tachycardia, and fatigue due to decreased cardiac output.
- Diagnosis:
- Echocardiogram: Reveals right atrial and ventricular diastolic collapse.
- ECG: May show low voltage and electrical alternans.
- Right Heart Catheterization: Shows equalization of pressures in all chambers, though rarely needed in acute cases.
- Management:
- Urgent Pericardiocentesis: Immediate drainage is essential for relief.
- Volume Expansion: Temporary measure to improve hemodynamics if pericardiocentesis is delayed.
Constrictive Pericarditis
- Pathophysiology: Chronic inflammation and scarring of the pericardium lead to diastolic restriction, causing symptoms similar to heart failure.
- Clinical Presentation:
- Signs of Right Heart Failure: Peripheral edema, ascites, and hepatomegaly.
- Kussmaul’s Sign: Paradoxical rise in jugular venous pressure on inspiration.
- Pericardial Knock: Early diastolic sound from abrupt cessation of ventricular filling.
- Diagnosis:
- Echocardiography: Shows pericardial thickening, septal bounce.
- CT or MRI: Useful for detecting pericardial calcification and confirming thickening.
- Right Heart Catheterization: Shows the “square root” sign in ventricular pressure tracings due to rapid early filling.
- Management:
- Diuretics: Initial management for volume overload.
- Pericardiectomy: Definitive treatment for symptomatic cases unresponsive to medical therapy.
Key Points
- Acute Pericarditis:
- Presents with pleuritic chest pain relieved by leaning forward; diffuse ST elevation on ECG.
- Treated with NSAIDs, colchicine, and corticosteroids if refractory.
- Pericardial Effusion:
- May be asymptomatic or cause dyspnea; echocardiography is the primary diagnostic tool.
- Observation for small effusions; pericardiocentesis if large or symptomatic.
- Cardiac Tamponade:
- Life-threatening, presents with Beck’s triad and pulsus paradoxus.
- Requires urgent pericardiocentesis.
- Constrictive Pericarditis:
- Causes right heart failure signs, Kussmaul’s sign, and pericardial knock.
- Managed with diuretics initially; pericardiectomy is definitive in refractory cases.