Noninvasive measurement of small local vibrations in the heart or arterial wall

In order to diagnose ventricular dysfunction or arteriosclerosis based on the acoustic characteristics of the heart muscle or the arterial walls, it is necessary to noninvasively measure small vibration signals from various parts of the ventricular or arterial walls. This is, however, difficult using previously proposed ultrasonic diagnostic methods or systems. We have already proposed a method for overcoming this problem and measuring small vibrations of the ventricle wall using ultrasound. This paper proposes a new method to accurately track the heart/aortic wall movement from both of the phase and magnitude of the demodulated signal to determine the position of the object, from which the velocity is estimated. By this method, small vibrations of heart wall or aortic wall with amplitudes of 10 approx. 100 μm on the motion due to heart beat with the large amplitude of 10 mm are successfully detected in the frequency range up to 1 kHz continuously for more than ten beat periods. The new method offers potential for research in acoustical diagnosis of heart dysfunction and atherosclerosis.