Honda H, Tani J, Miyazaki T, Koiwa Y, Takishima T, Shirato K
First Department of Internal Medicine, Tohoku University School of Medicine, Sendai.
Tohoku J Exp Med. 1995 Oct;177(2):125-37. doi: 10.1620/tjem.177.125.
(1) We measured the instantaneous systolic transfer function of an isolated canine left ventricle (LV) before and after the ligation of the left anterior descending coronary artery (LAD). The instantaneous transfer function before the ligation of the LAD showed a resonance curve whose peak frequency was 30 to 70 Hz. On the other hand, the transfer function 40 min after the ligation of the LAD showed a divided peak in the resonance curve. (2) We constructed a finite element model of a thick-walled spherical shell with a non-uniform structure. In this model, the myocardial elasticity and viscosity of the ischemic region are different from those of non-ischemic regions. One can calculate the theoretical transfer function using modal analysis and also estimate the elasticity and the viscous coefficient of both non-ischemic and ischemic myocardium by fitting the theoretical transfer function to the experimental one. (3) The estimated elasticity of the ischemic myocardium was three to five times larger than that of the non-ischemic myocardium. The estimated viscous coefficient of the ischemic myocardium was about half that of the non-ischemic myocardium. These results showed that ischemia alters the viscoelastic properties of the myocardium during systole as well as during diastole.
(1) 我们测量了在结扎左冠状动脉前降支（LAD）前后，离体犬左心室（LV）的瞬时收缩传递函数。结扎LAD前的瞬时传递函数呈现出一条共振曲线，其峰值频率为30至70赫兹。另一方面，结扎LAD后40分钟的传递函数在共振曲线中呈现出双峰。(2) 我们构建了一个具有非均匀结构的厚壁球壳有限元模型。在该模型中，缺血区域的心肌弹性和粘性与非缺血区域不同。可以使用模态分析计算理论传递函数，并通过将理论传递函数与实验传递函数拟合来估计非缺血和缺血心肌的弹性及粘性系数。(3) 估计缺血心肌的弹性比非缺血心肌大3至5倍。估计缺血心肌的粘性系数约为非缺血心肌的一半。这些结果表明，缺血在收缩期和舒张期均会改变心肌的粘弹性特性。
