Pericardial Disease for USMLE Step 1
Pericardial Disease for the USMLE Step 1 Exam
Types of Pericardial Disease
Pericardial disease includes several conditions affecting the pericardium, primarily acute pericarditis, pericardial effusion, cardiac tamponade, and constrictive pericarditis. Each condition has distinct diagnostic features and treatment strategies.
Acute Pericarditis
- Etiology:
- Infectious: Viral (most common, e.g., Coxsackievirus), bacterial (e.g., tuberculosis).
- Non-infectious: Post-myocardial infarction (Dressler syndrome), autoimmune conditions (e.g., lupus), uremia, and certain medications.
- Clinical Presentation:
- Chest Pain: Sharp, pleuritic pain, often relieved by sitting up and leaning forward.
- Fever and pericardial friction rub (best heard at the left sternal border).
- Diagnosis:
- ECG: Diffuse ST-segment elevation and PR-segment depression.
- Blood Tests: Elevated inflammatory markers (e.g., CRP, ESR) and sometimes mild elevation of cardiac biomarkers.
- Management:
- NSAIDs or Aspirin: First-line for symptom relief.
- Colchicine: Added to reduce recurrence risk.
- Glucocorticoids: Reserved for refractory cases or contraindications to NSAIDs, but increases recurrence risk.
Pericardial Effusion
- Etiology:
- Can arise from any cause of pericarditis, hypothyroidism, malignancy, or trauma.
- Effusion can vary in composition (e.g., serous, hemorrhagic, purulent).
- Clinical Presentation:
- Dyspnea and chest discomfort; large effusions can compress nearby structures, causing dysphagia or hoarseness.
- May be asymptomatic if fluid accumulates slowly.
- Diagnosis:
- Echocardiogram: Primary diagnostic tool, shows fluid accumulation and potential for tamponade.
- ECG: Low-voltage QRS complexes or electrical alternans with large effusions.
- Management:
- Observation: For small, asymptomatic effusions.
- Pericardiocentesis: For large or symptomatic effusions or if tamponade is present.
Cardiac Tamponade
- Pathophysiology: Rapid fluid accumulation compresses the heart, restricting ventricular filling and lowering cardiac output.
- Clinical Presentation:
- Beck's Triad: Hypotension, distended neck veins, muffled heart sounds.
- Pulsus Paradoxus: Drop in systolic blood pressure >10 mm Hg during inspiration.
- Symptoms: Dyspnea, tachycardia, and fatigue due to low cardiac output.
- Diagnosis:
- Echocardiogram: Key diagnostic tool; shows chamber collapse, indicating tamponade.
- ECG: May reveal low voltage and electrical alternans.
- Management:
- Urgent Pericardiocentesis: Immediate drainage to relieve tamponade.
- Volume Expansion: Temporary measure to maintain cardiac output if pericardiocentesis is delayed.
Constrictive Pericarditis
- Pathophysiology: Chronic pericardial inflammation leads to scarring and calcification, restricting ventricular filling.
- Clinical Presentation:
- Signs of Right Heart Failure: Peripheral edema, ascites, hepatomegaly.
- Kussmaul’s Sign: Jugular venous pressure rises on inspiration.
- Pericardial Knock: Early diastolic sound indicating abrupt cessation of ventricular filling.
- Diagnosis:
- Echocardiography: Shows septal bounce and pericardial thickening.
- CT or MRI: Detects pericardial thickening and calcification.
- Management:
- Diuretics: To manage volume overload.
- Pericardiectomy: Surgical removal of the pericardium is definitive for symptomatic patients.
Key Points
- Acute Pericarditis:
- Chest pain is sharp, pleuritic, and relieved by leaning forward.
- ECG shows diffuse ST-segment elevation; treated with NSAIDs, colchicine, and corticosteroids if refractory.
- Pericardial Effusion:
- May be asymptomatic or cause dyspnea; echocardiogram is diagnostic.
- Observation for small effusions; pericardiocentesis if large or causing tamponade.
- Cardiac Tamponade:
- Presents with Beck’s triad and pulsus paradoxus; urgent pericardiocentesis is required to relieve compression.
- Constrictive Pericarditis:
- Presents with signs of right heart failure, Kussmaul’s sign, and pericardial knock.
- Managed initially with diuretics; pericardiectomy is definitive in refractory cases.