Beck triad

Beck triad results from pericardial effusion causing increased intrapericardial pressure, which compresses the heart chambers and impairs diastolic filling. This leads to decreased stroke volume and cardiac output (hypotension), elevated systemic venous pressure due to impaired right heart filling (JVD), and muffled heart sounds from the fluid dampening cardiac auscultation. Cardiac tamponade is a medical emergency often caused by trauma (penetrating chest injury), malignancy, uremia, aortic dissection, post-MI free wall rupture, or viral/idiopathic pericarditis. Other associated findings include pulsus paradoxus (>10 mmHg drop in systolic BP during inspiration) and Kussmaul sign (paradoxical rise in JVP with inspiration, though more classic for constrictive pericarditis). Diagnosis is confirmed with echocardiography showing pericardial effusion with diastolic collapse of the right ventricle/atrium, or 'swinging heart' sign. ECG may show electrical alternans. Treatment is pericardiocentesis to relieve tamponade. Beck triad is classically tested but is present in only a minority of tamponade cases clinically, so absence does not rule out tamponade—this is an important board pearl. It's important to distinguish from other pericardial diseases: constrictive pericarditis presents differently (Kussmaul sign, pericardial knock) and pulsus paradoxus is more specific/sensitive for tamponade.