Research on diastolic properties of the myocardium by imaging propagation of shear wave along heart wall

通过对心肌运动的超声测量，我们已经发现脉冲波是由收缩末期二尖瓣关闭自发激发的。由于心肌粘弹性是评价心脏舒张特性的重要参数，本研究采用在体无创测量的方法，具体如下：1.采用稀疏扇形扫描，以足够高的帧频，在心壁沿着设置的数千个点上几乎同时测量脉冲波。连续的空间相位分布清楚地揭示了波沿心脏壁沿着的传播。对于每个频率分量确定波的相速度。通过比较兰姆波在血液中沿着粘弹性板传播时的相速度频散与理论频散，实现了对粘弹性板瞬时粘弹性的无创测量 ...更多信息 通过在弹性球壳中激励小脉冲，该弹性球壳被制成心脏的模型，我们证实可以测量球壳的粘弹性，误差小于通过机械测试测量的粘弹性的10%。4通过将所开发的方法应用于5个健康受试者，我们证实了连续心动周期中脉冲波传播速度的充分再现性。5我们证实了从5名受试者估计的粘弹性值之间的差异小于20%主动脉瓣关闭后粘弹性的瞬态变化与主动脉瓣关闭后粘弹性的瞬态变化相似。粘弹性估计值与文献中对犬心脏壁测量的结果相似。6通过将该方法应用于10例陈旧性心肌梗死患者，我们发现每个病变区域的振幅和传播速度均降低。这些结果与文献中使用纵波获得的结果一致。7总之，基于新的发现，我们开发了一种测量体内心肌粘弹性的方法。这些临床结果表明，该方法具有潜在的非侵入性揭示心肌异质性。少

By ultrasonic measurement of the myocardial motion, we have already found that pulsive waves are spontaneously excited by aortic-valve closure at end-systole. Since myocardial viscoelasticity is essential in the evaluation of heart diastolic properties, this study makes the physiological phenomenon to be measured noninvasively measured in vivo as follows:1 Using a sparse sector scan, the pulsive waves were measured almost simultaneously at several thousand points set along the heart wall at a sufficiently high frame rate. The consecutive spatial phase distributions clearly revealed wave propagation along the heart wall. The phase velocity of the wave is determined for each frequency component. By comparing the dispersion of the phase velocity with the theoretical one of the Lamb wave, which propagates along the viscoelastic plate immersed in blood, the instantaneous viscoelasticity is determined noninvasively.2 We realized the principle of the measurement in a clinical ultrasonic diagn … More ostic system.3 By actuating a small pulse in an elastic spherical shell, which was made as a model of the heart, we confirmed that the viscoelasticity of the spherical shell can be measured with an error less than 10% of the viscoelasticity measured by the mechanical test.4 By applying the developed method to 5 healthy subjects, we confirmed the sufficient reproducibility of the propagation velocity of the pulsive wave among the consecutive cardiac cycles.5 We confirmed that the difference among the viscoelasticity values estimated from the 5 subjects is less than 20% and the transient of the viscoelasticity just after the aortic valve closure is similar. The viscoelasticity estimates are similar to those measured for the canine heart wall in literature.6 By applying the method to 10 patients with old myocardial infarction, we found that the amplitude and the propagation speed were decreased in each of the diseased areas. These results correspond to that obtained by using the longitudinal waves in literature.7 In conclusion, based on the new findings, we developed a means to measure the myocardial viscoelasticity in vivo. These clinical results indicate that the method has a potential for noninvasively revealing myocardial heterogeneity. Less