Non-invasive evaluation of aortic valve stenosis by spectral analysis of heart murmurs

Assessing the severity of aortic valvular stenosis (AS) remains an important clinical problem. The turbulent pressure fluctuations generated by the confined jet downstream of an AS produce vibrations in the aortic wall. These vibrations are transmitted through the chest to the skin surface where they can be measured with a sensitive accelerometer as systolic ejection murmurs. Clinical experience has shown that stenoses with a large pressure difference across an obstruction such a severe AS are associated with mainly high frequency murmurs, and conversely minor stenoses are known to produce low frequency murmurs. The purpose of the present study was 1) to find the relationship between the severity of AS and the spectral distribution of energy of the systolic murmurs and 2) to measure the trans-thoracic attenuation of murmurs and its variation from patient to patient.