Pericarditis and Myocarditis for USMLE Step 3 & COMLEX-USA Level 3
Start your One-Week Free Trial
Already subscribed? Log in »
Pericarditis
- Etiology:
- Infectious: Viral (Coxsackievirus, echovirus, influenza), bacterial (tuberculosis, Streptococcus), fungal.
- Non-infectious:
- Post-MI (acute and Dressler syndrome).
- Autoimmune (systemic lupus erythematosus, rheumatoid arthritis).
- Uremia, malignancy, trauma, radiation therapy.
- Clinical Presentation:
- Chest pain: Sharp, pleuritic, relieved by sitting forward.
- Pericardial friction rub: Scratchy sound heard along the left sternal border.
- Fever and dyspnea if effusion develops.
- Diagnosis:
- ECG:
- Diffuse ST-segment elevation with PR-segment depression (early stages).
- Later stages show T-wave inversion and normalization.
- Echocardiography: Detects pericardial effusion and signs of tamponade.
- Lab tests: Elevated ESR, CRP; possible leukocytosis.
- Complications:
- Cardiac tamponade: Beck’s triad (hypotension, distant heart sounds, jugular venous distension).
- Constrictive pericarditis: Chronic fibrosis causing heart failure symptoms.
- Treatment:
- NSAIDs and colchicine: First-line therapy.
- Steroids: For refractory or autoimmune cases.
- Pericardiocentesis: For tamponade or large effusions.
- Antibiotics: In bacterial pericarditis.
- --
Myocarditis
- Etiology:
- Infectious: Viral (Coxsackievirus, adenovirus), bacterial (Lyme disease, Chagas disease), fungal, parasitic.
- Non-infectious:
- Autoimmune (sarcoidosis, giant cell myocarditis).
- Drug reactions (e.g., chemotherapy, hypersensitivity).
- Clinical Presentation:
- Chest pain: Mimics acute coronary syndrome.
- Heart failure symptoms: Dyspnea, orthopnea, edema.
- Palpitations and syncope: From arrhythmias.
- Systemic symptoms: Fever, myalgia, fatigue in viral myocarditis.
- Diagnosis:
- ECG: ST/T wave abnormalities, ventricular arrhythmias, heart block.
- Echocardiography: Reduced ejection fraction, ventricular dilation.
- Cardiac MRI: T2 hyperintensity (myocardial edema) and gadolinium enhancement.
- Endomyocardial biopsy: Gold standard in severe or refractory cases.
- Blood tests: Elevated troponin and BNP.
- Complications:
- Heart failure: Acute or chronic.
- Arrhythmias: Ventricular tachycardia or fibrillation.
- Dilated cardiomyopathy: Chronic inflammation and myocardial remodeling.
- Sudden cardiac death: From severe ventricular arrhythmias.
- Treatment:
- Supportive care: Oxygen, diuretics, ACE inhibitors, beta-blockers.
- Antiarrhythmics: For ventricular arrhythmias.
- Immunosuppressants: For autoimmune myocarditis (e.g., steroids).
- Mechanical support: ECMO or ventricular assist devices in severe heart failure.
- --
Differences Between Pericarditis and Myocarditis
- ECG Findings:
- Pericarditis: Diffuse ST elevation, PR depression.
- Myocarditis: Nonspecific ST/T changes, arrhythmias, heart block.
- Key Complications:
- Pericarditis: Cardiac tamponade, constrictive pericarditis.
- Myocarditis: Heart failure, dilated cardiomyopathy, sudden cardiac death.
- --
Key Points
- Pericarditis presents with pleuritic chest pain, pericardial rub, and diffuse ST-segment elevation. Management includes NSAIDs, colchicine, and pericardiocentesis if tamponade occurs.
- Myocarditis can mimic acute coronary syndrome and cause heart failure, arrhythmias, and dilated cardiomyopathy. Cardiac MRI and biopsy are crucial in severe cases.
- ECG findings help differentiate pericarditis (diffuse ST elevation) from myocarditis (arrhythmias, heart block).
- Complications: Pericarditis may lead to cardiac tamponade, while myocarditis can cause life-threatening ventricular arrhythmias.