A 58-year-old man develops acute pulmonary oedema 3 days after an inferior wall myocardial infarction. There is a new holosystolic murmur at the apex radiating to the axilla. Rupture of which structure is the likely cause?
- A Anterolateral papillary muscle
- B Interventricular septum
- C Posteromedial papillary muscle ✓
- D Free wall of the left ventricle
Correct answer: C. Posteromedial papillary muscle
Explanation
The posteromedial papillary muscle has a single blood supply from the posterior descending artery, making it vulnerable to rupture after inferior infarction. The anterolateral papillary muscle has dual supply from the left anterior descending and circumflex arteries and ruptures far less often. Septal rupture produces a harsh left parasternal murmur with a step-up in right ventricular oxygen saturation rather than an apical murmur radiating to the axilla.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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