A Study on Noninvasive Ultrasonic Measurement of Minute Mechanical-Excitation Wave-front Propagation in Human Myocardial Tissue and Its Visualization

心脏收缩序列的复杂性仍未完全被了解，因为与收缩直接相关的动态机械兴奋过程不能基于电磁现象被准确测量。通过开发一种新的具有高时间和空间分辨率的无创成像方法，本研究首次发现机械波前的传播发生在心脏收缩序列的开始处(比通常所接受的收缩开始时间早约60ms)。从室间隔的心尖侧产生一个幅度为几十微米的微小速度分量，它从心尖传播到后壁底部，然后从底部传播到间隔心尖，传播速度为3-9m/S。这种动态测量方式也适用于生物中的各种组织。

Complexity of the cardiac contraction sequence is still not fully understood because the dynamic mechanical excitation process, which directly correlates with contraction, cannot be accurately measured based on the electro-magnetic phenomena. By developing a noninvasive novel imaging modality with high temporal and spatial resolutions, the present study shows that the propagation of the mechanical wave-front occurs at the beginning of cardiac contraction sequence for the first time (about 60 ms prior to the ordinarily accepted onset time of the contraction). From the apical side of the interventricular septum, a minute velocity component with an amplitude of several tenth micrometers is generated and it propagates from the apex to the base of the posterior wall, and then from the base to the apex of the septum, with a propagation speed of 3-9 m/s. This dynamic measurement modality is also applicable to various tissues in biology.