Review Question - QID 100629

Papillary muscle rupture is a potential complication of myocardial infarction and can cause severe mitral regurgitation. The posteromedial papillary muscle in the left ventricle is the most susceptible to ischemic damage because it has only a single blood supply from either the right coronary artery or left circumflex artery, depending on the dominance.

The best indicator for severity of mitral regurgitation on physical examination is the presence of an S3. The S3 indicates left ventricular volume overload and increased diastolic filling pressure. Of note, the intensity of the mitral regurgitation murmur does not correlate well with the regurgitant volume. The rupture of the anterolateral papillary muscle is less common than the posteromedial papillary muscle because the anterolateral papillary muscle has a dual blood supply (left anterior descending and left circumflex artery), while the posteromedial papillary muscle has a single blood supply. Papillary muscle rupture usually occurs 5-10 days after MI. Other complications such as tamponade, free wall rupture, and septal rupture may happen at this point. Prior to this point the most common complication is arrhythmia, and past 10 days, ventricular aneurysms are most likely to occur.

Incorrect Answers:
Answer 1, 2, & 3: Rupture of this papillary muscle would lead to tricuspid regurgitation.
Answer 4: Rupture of this papillary muscle could possibly lead to mitral regurgitation but due to its dual blood supply it is less often ruptured than the posterior papillary muscle.