A 61-year-old man presents 3 hours after onset of anterior chest pain. ECG shows ST elevation in leads V1–V4. He undergoes primary PCI successfully. On day 3, he develops sudden hypotension, a new loud holosystolic murmur at the left sternal border, and a thrill. Oxygen saturation step-up is noted from right atrium to right ventricle on Swan-Ganz catheterisation. The complication is:
- A Ventricular septal rupture (post-infarct VSD) ✓
- B Acute papillary muscle rupture causing mitral regurgitation
- C Left ventricular free wall rupture
- D Aortic dissection extending retrograde
Correct answer: A. Ventricular septal rupture (post-infarct VSD)
Explanation
Post-infarct ventricular septal rupture (VSD) classically presents 3–5 days after anterior MI with a new loud pansystolic murmur and haemodynamic compromise; the hallmark is an oxygen step-up from right atrium to right ventricle on right heart catheterisation due to left-to-right shunting. Papillary muscle rupture also causes a loud murmur but it is associated with massive mitral regurgitation and pulmonary oedema without an oxygen step-up in the RV. Free wall rupture causes tamponade without a murmur. Aortic dissection does not produce an RV oxygen step-up.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.