A 62-year-old man develops severe mitral regurgitation three days after an acute inferior myocardial infarction. Which anatomical feature explains why rupture of one specific papillary muscle causes this complication?
- A The anterolateral papillary muscle has a single blood supply from the left circumflex artery
- B Both papillary muscles are supplied exclusively by the left anterior descending artery
- C The posteromedial papillary muscle usually has a single blood supply from the posterior descending artery ✓
- D The posteromedial papillary muscle is supplied by two separate coronary arteries
Correct answer: C. The posteromedial papillary muscle usually has a single blood supply from the posterior descending artery
Explanation
The posteromedial papillary muscle of the left ventricle is typically supplied by a single vessel, the posterior descending artery, which arises from the right coronary artery in right-dominant hearts. Inferior infarction can therefore devascularize it completely, causing rupture and acute regurgitation. The anterolateral papillary muscle has a dual supply from the left anterior descending and circumflex arteries, making isolated rupture far less common.
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.