Measurement of sounds generated by mechanical aortic and mitral heart valve prostheses

Sounds and vibrations produced by prosthetic heart valves may reflect the structural and functional integrity of their components. In fact early signs of valve failure might be disclosed by spectral analysis of the opening or closing sounds. Mechanical heart valve prostheses generate clicking sounds as a result of the periodic opening and closing movement of the occluder. While the opening click is usually only detectable with phonocardiography, the closing click may well be audible over a considerable distance and may be annoying to the patients as well as to their families. In order to investigate these phenomena properly in humans, it is necessary to pick up the sounds at a point at the chest and during physical and physiological conditions, which gives the best signal-to-noise ratio (S/N). Therefore, the purpose of the study was to determine the location on the human chest with the highest S/N of precordial sounds from mechanical aortic and mitral valve prostheses. This was accomplished by precordial mapping of sound distribution as a function of patient position, respiratory phase and transducer type. The results suggest that sounds from mechanical aortic and mitral valve prostheses should be measured in the precordial area of the fourth left and fifth left intercostal space near the sternum