Pericardial and Myocardial Disease
Core concepts
Pericardial disease includes acute pericarditis, pericardial effusion, tamponade, and constrictive pericarditis. Myocardial disease includes myocarditis, stress cardiomyopathy, infiltrative disease, sarcoidosis, and toxin-related injury. Acute pericarditis is diagnosed by two of four criteria: chest pain, friction rub, diffuse ST elevation or PR depression, and new effusion. Tamponade physiology includes hypotension, elevated JVP, pulsus paradoxus, and echocardiographic right-heart collapse. Constrictive pericarditis causes right-heart failure, a pericardial knock, and septal bounce.
Question traps
Do not label diffuse ST elevation as STEMI without considering pericarditis; reciprocal ST depression is uncommon in pericarditis. Pulsus paradoxus is not specific. Myocarditis can mimic MI with troponin release and normal coronaries. Stress cardiomyopathy often follows physical or emotional stress and has regional wall-motion abnormalities beyond a single coronary territory. Avoid NSAIDs in myocarditis with significant LV dysfunction.
Worked example / rule of thumb
A young patient with pleuritic chest pain, diffuse ST elevation, and PR depression is treated for acute pericarditis with NSAIDs and colchicine after risk stratification. Rule: diffuse ST elevation plus PR depression favors pericarditis; focal ST elevation with reciprocal changes favors ischemia.