Question 1
A 68-year-old female on post-operative day 4 following an inferoposterior STEMI suddenly develops acute dyspnea, hypotension, and pulmonary edema. Physical examination reveals a new, loud apical holosystolic murmur radiating to the axilla along with a palpable thrill. Bedside echocardiogram confirms acute severe mitral regurgitation. Which structural vessel/structure involvement is the primary cause of this complication?
Rationale
Correct Answer: B. Rupture of the posteromedial papillary muscle due to right/circumflex coronary artery occlusionHigh-Yield Explanation:
Acute papillary muscle rupture occurs most commonly after an inferoposterior myocardial infarction caused by right or circumflex coronary artery occlusion. The posteromedial papillary muscle has a single blood supply (unlike the anterolateral papillary muscle, which has a dual blood supply), making it vulnerable to ischemic necrosis and rupture, resulting in acute severe mitral regurgitation and sudden pulmonary edema.
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