CHANGE IN AMPLITUDE DISTRIBUTIONS OF DOPPLER SPECTROGRAMS RECORDED BELOW THE AORTIC-VALVE IN PATIENTS WITH A VALVULAR AORTIC-STENOSIS

Amplitude distributions of Doppler spectrograms were characterized in a group of 22 patients having no aortic pressure gradient and another group of 26 patients having a stenotic aortic valve. Specifically, for each patient, the ratios of the mean amplitude in three normalized frequency bands (low, middle and high) to the mean amplitude of the Doppler spectrogram computed in selected portions of the systolic period were considered. Pulsed-wave Doppler spectrograms were recorded by positioning the sample volume in the left ventricular outflow tract, approximately 1 cm below the aortic valve. Statistically significant differences were found between the middle (p = 0.041) and high (p = 0.028) frequency bands of Doppler signals recorded from the two groups of patients. The differences observed are believed to be attributed to blood flow eddies generated below the stenotic aortic heart valve and to changes in blood flow orientation.