A 62-year-old man develops acute pulmonary edema and a loud pansystolic murmur at the apex two days after an inferior myocardial infarction. Echocardiography shows flail posterior leaflet of the mitral valve. Which structure has most likely ruptured?
- A Anterior leaflet of the mitral valve
- B Anterolateral papillary muscle
- C Posteromedial papillary muscle ✓
- D Interventricular septum
Correct answer: C. Posteromedial papillary muscle
Explanation
The posteromedial papillary muscle is supplied solely by the posterior descending artery from the right coronary artery, so it is vulnerable after an inferior infarct. The anterolateral papillary muscle has a dual supply from the anterior interventricular (LAD) diagonal and circumflex marginal branches, making its rupture far less common. C septal rupture would produce a left-to-right shunt rather than isolated severe mitral regurgitation.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.