A 78-year-old woman is hospitalized due to acute myocardial infarction. The patient had been having intermittent chest pain for 3 days and came to the hospital when the pain became unremitting. She has type 2 diabetes mellitus, but her medical follow-up has been poor. On the third day of hospitalization, the patient has sudden-onset shortness of breath due to pulmonary edema. Echocardiography confirms severe mitral regurgitation. She is taken immediately to surgery, which reveals rupture of the posteromedial papillary muscle. This patient's finding typically suggests compromised blood flow through which of the following coronary arteries?

Question

A 78-year-old woman is hospitalized due to acute myocardial infarction.  The patient had been having intermittent chest pain for 3 days and came to the hospital when the pain became unremitting.  She has type 2 diabetes mellitus, but her medical follow-up has been poor.  On the third day of hospitalization, the patient has sudden-onset shortness of breath due to pulmonary edema.  Echocardiography confirms severe mitral regurgitation.  She is taken immediately to surgery, which reveals rupture of the posteromedial papillary muscle.  This patient's finding typically suggests compromised blood flow through which of the following coronary arteries?

Quizplus · Accepted Answer

11ec160b_355c_380a_9249_57198e559413_MD0001_00 The mitral valve apparatus consists of the mitral valve annulus, anterior and posterior mitral leaflets, and chordae tendineae, which are tethered to the left ventricular wall via the anterolateral and posteromedial papillary muscles. Pathologic processes that disrupt any of these structures can lead to improper alignment of the mitral leaflets, resulting in mitral regurgitation and pulmonary edema. The patient's mitral regurgitation is the result of papillary muscle rupture, a life-threatening mechanical complication typically occurring 3-5 days following acute myocardial infarction. The anterolateral papillary muscle has a dual blood supply from the left anterior descending (LAD) and left circumflex arteries. In contrast, the posteromedial papillary muscle is supplied solely by the posterior descending artery, a branch of the right coronary artery (right dominant circulation) or left circumflex artery (left dominant circulation). Because blood flow to the posteromedial papillary muscle depends on a single artery, it is more likely to become ischemic and rupture following myocardial infarction. (Choice A) The conus artery is an early branch of the proximal right coronary artery; it supplies the anterior area of the interventricular septum and conus of the pulmonary artery. (Choice B) Diagonal arteries branch from the LAD artery and supply blood to the anterolateral walls of the left ventricle. (Choice C) The LAD artery supplies the anterior two thirds of the interventricular septum, anterior wall of the left ventricle, and anterolateral papillary muscle. Abrupt occlusion of the LAD rarely results in ischemic rupture of the anterolateral papillary muscle as this muscle also receives blood supply from the left circumflex artery. (Choice D) The obtuse (left) marginal artery is a branch of the left circumflex artery and supplies the lateral wall of the left ventricle. Educational objective: Papillary muscle rupture is a life-threatening complication that typically occurs 3-5 days after myocardial infarction and presents with acute mitral regurgitation and pulmonary edema. The posteromedial papillary muscle is supplied solely by the posterior descending artery, making it susceptible to ischemic rupture. __________ References: A forgotten devil; rupture of mitral valve papillary muscle. (http://www.ncbi.nlm.nih.gov/pubmed/23569560)

A 78-Year-Old Woman Is Hospitalized Due to Acute Myocardial Infarction