We have previously developed a new method for accurately tracking the movement of the heart wall based on both the phase and magnitude of the demodulated signals to determine the instantaneous position of an object. By this method, velocity signals of the heart wall with small amplitudes less than several micrometers on the motion resulting from a heartbeat can be accurately detected. Moreover, the method has been applied to multiple points preset in the heart wall along an ultrasonic beam so that the spatial distributions of the local change in thickness during one cardiac cycle is determined. In this paper, the method is applied to the free wall of the right ventricle (RV), the interventricular septum (IVS), and the posterior wall of the left ventricle (LV). From the relationships among the results for these parts of the heart, new findings which characterize the velocity signals and the change in thickness in each cardiac period are described. This method offers potential for quantitative myocardial diagnosis.
Anthracyclines are among the most effective and widely used anticancer drugs; however, their use is limited by serious cardiotoxicity. Early detection is necessary to prevent the high mortality rate associated with heart failure (HF). We evaluated cardiac function in 142 patients using conventional echocardiography and the phased tracking method (PTM), which was measured using the minute vibration and the rapid motion components, neither of which is recognized in standard M‐mode nor in tissue Doppler imaging. For systolic function comparison, we compared left ventricular ejection fraction (LVEF) in conventional echocardiography with the average velocity of ventricular septum myocytes (Vave) in the PTM. The Vave of 12 healthy volunteers was 1.5 (m/s)/m or more. At baseline of 99 patients, there was a positive correlation between LVEF and Vave in all patients. There were no significant differences in baseline cardiac function between patients with and without HF. There was a negative correlation between the cumulative anthracycline dose and LVEF or Vave among all patients. We determined that Vave 1.5 (m/s)/m was equivalent to LVEF 60%, 1.25 (m/s)/m to 55%, and 1.0 (m/s)/m to 50%. During the follow‐up period, there was a pathological decrease in LVEF (<55%) and Vave (<1.25 m/s/m) in patients with HF; decreases in Vave were detected significantly earlier than those in LVEF (P < 0.001). When Vave declined to 1.5 (m/s)/m or less, careful continuous observation and cardiac examination was required. When Vave further declined to 1.0 (m/s)/m or lower, chemotherapy was postponed or discontinued; thus, serious drug‐induced cardiomyopathy was avoided in patients who did not relapse. The PTM was superior to echocardiography for early, noninvasive detection and intermediate‐term monitoring of left ventricle systolic function associated with anthracycline chemotherapy, among patients with hematologic malignancies. The PTM was an effective laboratory procedure to avoid the progression to serious cardiomyopathy.
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