First heart sound spectra in relation to anterior mitral-leaflet closing velocity

A mathematical model is presented to relate mitral valve leaflet closing velocity to the subsequent vibrational magnitude following valve closure. This relationship is investigated experimentally by means of phonocardiographic and echocardiographic recordings from 17 human subjects. Fast Fourier transform analysis of digitised first heart sounds from each subject reveals that the sound intensities in different frequency bands are not uniformly related to the valve-leaflet closing velocity, obtained from the anterior mitral leaflet echocardiogram. It is found that, in the frequency range up to 150 Hz, closing velocity correlates best with sound intensity in the 30–45 hz bandwidth.