Assessing the severity of aortic valve stenosis by spectral analysis of cardiac murmurs (spectral vibrocardiography). Part II: Clinical aspects.

Assessing the severity of aortic stenosis remains an important clinical problem. The turbulent pressure fluctuations generated by the jet downstream of the stenotic valve produce vibrations in the aortic wall. These vibrations are transmitted through the chest to the skin surface, where they can be recorded as systolic ejection murmurs. The purpose of the present study was to estimate the transvalvular aortic pressure difference by spectral analysis of heart murmurs (spectral vibrocardiography). Forty-four patients with clinical signs of aortic stenosis underwent cardiac catheterization to measure the transvalvular pressure difference. In a double blind prospective study, precordial vibrations were measured prior to catheterization using a dedicated heart sound analyzer (Vibrocard 2000) to calculate the spectral ratio of murmur energy between 100-500 Hz and 20-500 Hz. Three different weighting filters were used to compensate for individual differences in the transthoracic attenuation of murmurs. The square root of the murmur energy ratio correlated linearly with the mean transvalvular pressure difference (r = 0.80, SEE = 13 mmHg) and with the peak transvalvular pressure difference (r = 0.81, SEE = 16 mmHg). The use of individual compensation filters improved the correlation. This study shows that it is possible to estimate the transvalvular pressure difference in patients with aortic valve stenosis by spectral analysis of heart murmurs. It is a fast, simple and cost effective technique, which requires less skill than conventional methods.