papillary muscle

Papillary muscles are specialized cardiac muscle structures that play a crucial role in atrioventricular valve function. The left ventricle contains two papillary muscles (anterolateral and posteromedial), while the right ventricle typically has three (anterior, posterior, and septal). These muscles contract during systole, creating tension in the chordae tendineae to prevent the mitral and tricuspid valve leaflets from prolapsing into the atria. The posteromedial papillary muscle of the left ventricle is particularly vulnerable to ischemia because it receives blood supply from only the posterior descending artery (single blood supply), whereas the anterolateral papillary muscle has dual blood supply from both the left anterior descending and left circumflex arteries. Papillary muscle rupture is a serious complication of myocardial infarction, typically occurring 2-7 days post-MI, and presents with acute severe mitral regurgitation, pulmonary edema, and cardiogenic shock. This is a surgical emergency requiring immediate intervention. Papillary muscle dysfunction (without complete rupture) can also occur and presents with varying degrees of mitral regurgitation.