Systolic Murmur in the Mitral Area
Classification by Timing
- A holosystolic murmur begins with S1 and continues through systole until S2, indicating continuous regurgitant flow throughout ventricular contraction, and represents chronic mitral regurgitation with established pressure gradient between left ventricle and left atrium, as recommended by the American College of Cardiology 2, 3
- Early systolic murmurs begin with S1 but end in midsystole, and occur in acute mitral regurgitation, such as papillary muscle rupture or acute chordal rupture, according to the American College of Cardiology 2, 6
- Late systolic murmurs start well after ejection and end before or at S2, are soft or moderately loud, high-pitched murmurs at the left ventricular apex, and are classic for mitral valve prolapse with or without midsystolic clicks, as described by the American College of Cardiology 2, 5
- Midsystolic murmurs can occur with functional mitral regurgitation, and echocardiography is necessary to distinguish from benign flow murmurs or aortic stenosis, as recommended by the American College of Cardiology 1, 7
Diagnostic Approach
- Isometric handgrip exercise increases mitral regurgitation murmur intensity, as noted in Circulation 4, 5
- Respiration affects murmur intensity, with left-sided murmurs louder during expiration, according to the American College of Cardiology 4, 5
- Standing diminishes most murmurs except hypertrophic cardiomyopathy and mitral valve prolapse, which lengthen and intensify, as described in Circulation 4, 5
Echocardiography Indications
- Urgent echocardiography is required for new systolic murmur with acute heart failure, hypotension, or shock, and for unexplained heart failure with normal LV function on clinical assessment, although specific citation is not provided, the American College of Cardiology recommends early assessment 2