Review Question - QID 104207

The clinical presentation and the new holosystolic murmur at the apex are consistent with mitral regurgitation associated with papillary muscle rupture, a life-threatening complication of acute myocardial infarction.

In acute mitral regurgitation, an abrupt elevation of left atrial pressure in the setting of normal atrial size and compliance causes back flow into the pulmonary circulation, and resultant pulmonary edema. Cardiac output decreases because of decreased forward flow, and hypotension or shock may also occur. The murmur of mitral regurgitation is characterized by a holosystolic murmur loudest at the apex, which radiates to the axilla and becomes softer with decreased blood flow to the heart (Valsalva maneuver, standing). Causes of acute mitral regurgitation include infective endocarditis and papillary muscle rupture (given their attachment to the atrioventricular valves via the chordae tendineae). Causes of chronic mitral regurgitation include rheumatic fever, degenerative valvular disease (e.g. from mitral valve prolapse), and cardiomyopathy.

Incorrect Answers:
Answer 1: Aortic stenosis is associated with a mid-to-late systolic murmur and diminished carotid upstrokes.
Answer 2: Aortic regurgitation is associated with a blowing diastolic murmur, wide pulse pressure, systolic hypertension, and hyperdynamic circulation.
Answer 3: Mitral valve prolapse is associated with a mid-systolic click and a mid-to-late systolic murmur, which increases with standing.
Answer 4: Mitral stenosis is associated with a diastolic murmur and, sometimes an opening snap.