A patient 72 hours post-STEMI develops sudden hypotension, elevated JVP, clear lungs, and a new loud holosystolic murmur at the left sternal border with a thrill. ECG shows sinus tachycardia with Q waves in inferior leads. What is the most likely diagnosis?
- A Acute severe mitral regurgitation due to papillary muscle rupture
- B Left ventricular free wall rupture with tamponade
- C Ventricular septal rupture (VSR) ✓
- D Right ventricular infarction
Explanation
Ventricular septal rupture post-MI characteristically presents 3–7 days after infarction (with thrombolytics, earlier; with primary PCI era, slightly different timing) with sudden haemodynamic deterioration. The murmur of VSR is a harsh holosystolic murmur maximal at the left lower sternal border, often with a palpable thrill — distinguishing it from papillary muscle rupture (which has a murmur maximal at apex, radiating to axilla). Clear lungs with elevated JVP indicate right-to-left shunting effects or RV volume overload. Echocardiography is diagnostic. Papillary muscle rupture causes acute pulmonary oedema (not clear lungs). Free wall rupture usually causes tamponade with equalization of pressures and rapid haemodynamic collapse without a murmur.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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