Papillary Muscle Rupture

Papillary muscle rupture is a rare but potentially fatal complication, typically occurring after myocardial infarction or due to infective endocarditis. Acute rupture often results in severe mitral valve regurgitation, leading to acute life-threatening cardiogenic shock and pulmonary edema. The heart contains 5 papillary muscles originating from the ventricular walls (see . Anatomy of the Heart). These muscles attach to the tricuspid and mitral valve leaflets through the chordae tendineae, preventing ventricular blood regurgitation by stabilizing the valves during systole. Three papillary muscles—anterior, posterior, and septal—attach to the tricuspid valve, whereas two—anterolateral and posteromedial—connect to the mitral valve (see . Mitral Valve Leaflets). Rupture of the tricuspid papillary muscles can occur due to myocardial ischemia, trauma, or infective endocarditis. Papillary muscle dysfunction causes blood to regurgitate through the valves, leading to backflow of blood that can result in left- or right-sided heart failure. Papillary muscle rupture was described in the literature as early as 1948. Visualization of rupture through two-dimensional echocardiography was first reported in 1981. Transesophageal echocardiography was first used to identify the condition in 1985. Papillary muscle rupture is a rare but severe mechanical complication that can occur following an acute myocardial infarction, affecting 0.07% to 0.26% of patients. Despite the condition's rarity, papillary muscle rupture contributes to 5% of postmyocardial infarction mortality. Papillary muscle rupture leads to severe mitral valve regurgitation, often resulting in cardiogenic shock and pulmonary edema, necessitating immediate medical intervention. A classic scenario involves a patient with a myocardial infarction affecting the posterior descending coronary artery's territory who develops sudden, decompensated heart failure 2 to 7 days after the infarction. The anterolateral and posteromedial papillary muscles play a key role in maintaining mitral valve function, with the anterolateral muscle receiving a dual blood supply and the posteromedial muscle supplied solely by the posterior descending coronary artery. Due to this single blood supply, the posteromedial papillary muscle is more likely to rupture following a myocardial infarction. Mortality is very high without timely surgical treatment.