Hemodynamic determinants of the frequency and amplitude of a musical murmur produced by a regurgitant mitral bioprosthetic valve.

The purpose of this study was to assess the hemodynamic determinant of the amplitude and frequency of a musical murmur produced by a regurgitant degenerated bioprosthetic valve in the mitral position. The prosthetic valve, obtained at surgery, was studied in the mitral position of an in vitro pulse duplicating system. In vitro, the valve produced a musical murmur that was caused by flutter of a flail leaflet. When the peak pressure difference between the left ventricle and left atrium was increased from 95 to 150 mm Hg, the fundamental frequency of the musical murmur increased from 91 to 187 hertz and the amplitude increased from 2,080 to 11,420 dynes/cm2. The fundamental frequency of the musical murmur was linearly related to the peak systolic pressure difference between the left ventricle and the left atrium (correlation coefficient [r] = 0.99). Similarly, the fundamental frequency of the musical murmur was linearly related to the magnitude of regurgitant flow across the valve (r = 0.99); and the regurgitant flow as expected was linearly related to the systolic pressure difference between the left ventricle and left atrium. The amplitude of the musical murmur was also related to both the peak systolic pressure difference between the left ventricle and left atrium (r = 0.99) and the magnitude of regurgitant flow (r = 0.99). These results indicate that the magnitude of regurgitant flow, determined by the systolic pressure difference between the left ventricle and left atrium, was a determinant of both the amplitude and the frequency of the musical murmur.