What are the classic signs of cardiac tamponade and which ECG finding is common?

• A. Orthopnea and bibasilar crackles; Q waves
• B. Hypertension, wide pulse pressure; peaked T waves
• C. Chest pain improved by leaning forward; ST elevations in II, III, aVF
• D. Hypotension, jugular venous distension, muffled heart sounds; electrical alternans on ECG

Answer: (D)

Cardiac tamponade happens when pericardial fluid accumulates and prevents the heart from filling properly during diastole, reducing preload and cardiac output. The hallmark signs are hypotension from decreased stroke volume, jugular venous distension reflecting elevated right-sided pressures, and muffled heart sounds due to the surrounding fluid dampening sound transmission. You may also see pulsus paradoxus, where there’s a greater drop in blood pressure during inspiration. On the ECG, electrical alternans is common—QRS complex amplitude varies with each beat because the heart swings within the fluid-filled pericardial sac; sometimes the overall voltage is low.

The other choices describe different problems. Orthopnea and crackles point to congestive heart failure, not tamponade, and Q waves suggest prior myocardial infarction. Hypertension with a wide pulse pressure hints at aortic regurgitation, while peaked T waves align with hyperkalemia or ischemia. Chest pain that improves leaning forward and ST elevations in inferior leads fit acute pericarditis or infarction, not tamponade. The combination of hypotension, JVD, muffled heart sounds, and electrical alternans best fits tamponade.