A 63-year-old man comes to the emergency department with 2 hours of chest pain and shortness of breath. The pain started as lower sternal discomfort that he attributed to indigestion, but then spread all over the anterior chest. The patient has never had similar pain before. Medical history includes hypertension, hyperlipidemia, and diet-controlled type 2 diabetes mellitus. The patient is an ex-smoker with a 20-pack-year history. On cardiac auscultation, a systolic murmur is heard. Basilar crackles are present on both sides. After initial evaluation, the patient is taken to the cardiac catheterization laboratory and is found to have a coronary artery occlusion, which is successfully revascularized. The next morning, the patient appears comfortable and wants to go home. The lungs are clear on auscultation, and no heart murmur is present. The murmur heard during initial presentation is most likely explained by a pathologic process involving which of the following structures?

Question

A 63-year-old man comes to the emergency department with 2 hours of chest pain and shortness of breath.  The pain started as lower sternal discomfort that he attributed to indigestion, but then spread all over the anterior chest.  The patient has never had similar pain before.  Medical history includes hypertension, hyperlipidemia, and diet-controlled type 2 diabetes mellitus.  The patient is an ex-smoker with a 20-pack-year history.  On cardiac auscultation, a systolic murmur is heard.  Basilar crackles are present on both sides.  After initial evaluation, the patient is taken to the cardiac catheterization laboratory and is found to have a coronary artery occlusion, which is successfully revascularized.  The next morning, the patient appears comfortable and wants to go home.  The lungs are clear on auscultation, and no heart murmur is present.  The murmur heard during initial presentation is most likely explained by a pathologic process involving which of the following structures?

Quizplus · Accepted Answer

11ec160b_38dd_20ea_9249_a71313689804_MD0001_00 This patient with myocardial infarction developed a new systolic murmur that resolved following revascularization, which is consistent with mitral regurgitation (MR) due to papillary muscle dysfunction. Myocardial infarction can cause ischemia of the papillary muscle and the adjacent LV wall on which it is mounted. This results in hypokinesis and outward displacement of the papillary muscle, creating increased tension on the attached chordae tendineae and preventing complete closure of the corresponding mitral valve cusp. Timely restoration of adequate blood supply with coronary revascularization restores papillary muscle and LV wall motion, often leading to resolution of the MR. In contrast to papillary muscle dysfunction, papillary muscle rupture is a mechanical complication of MI that occurs acutely or within 3-5 days and leads to acute MR; it does not resolve with coronary revascularization and typically requires surgical repair. (Choices A and B) Aortic root and aortic valve leaflet function are not directly affected by myocardial ischemia and would not explain a systolic murmur during acute MI. (Choice C) Rupture of the interventricular septum can occur acutely or within 3-5 days of acute MI. Patients have sudden-onset hypotension, dyspnea, pulmonary edema, and a harsh, holosystolic murmur at the left sternal border with palpable thrill. The condition does not resolve with coronary revascularization and typically requires surgical repair. (Choice D) Mitral valve chordae tendineae are not directly affected by myocardial ischemia; however, rupture resulting in acute MR can occur in patients with myxomatous mitral valve disease (mitral valve prolapse), rheumatic fever, or endocarditis. Educational objective: Myocardial infarction that causes ischemia of the papillary muscle or nearby left ventricular wall can result in acute mitral regurgitation with development of a new systolic murmur. Timely restoration of blood flow can improve papillary muscle dysfunction and lead to resolution of the regurgitation. __________ References: Acute valvular regurgitation. (http://www.ncbi.nlm.nih.gov/pubmed/19564568) Ischemic mitral regurgitation on the threshold of a solution: from paradoxes to unifying concepts. (http://www.ncbi.nlm.nih.gov/pubmed/16061756)

A 63-Year-Old Man Comes to the Emergency Department with 2