A new method for measuring small local vibrations in the heart using ultrasound

Abstract

In order to diagnose ventricular dysfunction based on the acoustic characteristics of the heart muscle of the ventricle, it is necessary to detect vibration signals from various parts of the ventricular wall. This is, however, difficult using previously proposed ultrasonic diagnostic methods or systems. The reason is that the amplitude of the cardiac motion is large during one beat period which produces large fluctuations in the transit time required for ultrasonic waves to travel from the transducer to the heart and back. This paper proposes a new method for overcoming this problem and accurately measuring small vibrations of the ventricle wall using ultrasound. In this method, the demodulated ultrasound signal reflected at the heart wall is converted from analogue to digital (A/D) signal at a high sampling frequency; from the resultant digital signal, the velocity of the wall is accurately obtained over a wide dynamic range based on the Doppler effect. The proposed method is preliminarily applied to the detection of small vibrations on the aortic wall and the interventricular septum. The new method offers potential for research in acoustical diagnosis of heart and artery dysfunction.

ECG-gated, Mechanical and Electromechanical Wave Imaging of Cardiovascular Tissues In Vivo

“…A significant compliance increase has been reported with age (Rogers et al 2001) and with atherosclerosis (Wang et al 2000). Moreover, further evidence of rapid transient motion in cardiovascular tissues was found by Kanai et al (1993; inside the heart. They found that a transient mechanical wave was generated at the root of the aortic valve, due to a strong mechanical effect upon valve closure.…”

“…Kanai et al (1993) developed a customized ultrasound system that used a small number of ultrasound beams distributed over a large field-of-view. Using this technique, they were able to simultaneously measure the tissue motion in the myocardium using 16 ultrasound beams at a high frame rate (450 Hz).…”

A composite high-frame-rate system for clinical cardiovascular imaging

“…Transient waves were also detected and imaged during propagation, clockwise or counterclockwise depending on the cardiac phase, along the myocardial wall. Those waves could not be detected by standard 2-d echocardiography, which typically operates at 60 to 90 Hz or 3-d echocardiography (15)(16)(17)(18)(19)(20). Fig.…”

“…others, such as Konofagou et al [17] and d'hooge et al [18], increased the frame rate of the rF images to above 200 Hz by reducing the size of the field of view and the total number of rF imaging lines. Kanai et al [19], [20] used a sparse sector-scan format, in which the number of ultrasound beams was decreased to about 16 to achieve the peak frame rate of 450 Hz. The onset of "pulsive waves" in the heart wall at end-systole and the propagation of spontaneous vibrations was estimated using a phased-tracking method in human subjects [6], [19], [21], [22].…”

Vibration parameter estimation methods for ultrasonic measurement systems – a review

“…(12) Effects of large value of β: Doppler sidebands with mean frequency and its harmonics cannot be ignored if β value is large [44]. (13) Systematic error in zero-crossing: In the measurement of angular velocity vibrations of rotating shafts, the zero-crossing method introduces a systematic error dependent on the frequency of the vibration harmonic [72]. (14) Pull-in-range of PLL: Frequency demodulation as well as β estimation would be possible only if the carrier frequency variation is within the pull-in-range of the PLL.…”