Effect of mechanical synchrony on ventricular contractility

我们研究心肌机械同步如何影响心室收缩性。为了分离心肌时变特性E(t)和心脏收缩同步性s(t)，我们假设时变心室特性E(t)可以通过s(t)和E(t)的卷积来近似。为了检验这一假设，我们使用时域直接反卷积技术确定了离体交叉循环犬心脏的e(t)。结果表明，从收缩早期得到的a(t)比从收缩后期得到的机械收缩持续时间更长。由于电去极化从心内膜向心外膜传播，也就是说，心内膜的机械收缩持续时间要比心外膜长。事实证明，心脏的质量起搏导致比心房起搏更低的收缩性。如果卷积模型是健全的，我们应该能够得到e(t)，甚至从心室颤动的心脏。我们用傅里叶分析了颤动心脏的左心室压力，并使用同态反卷积技术对其进行了反卷积。由此确定的e(t)与时域反卷积得到的结果相当吻合。因此，左心室的卷积模型似乎完整地表征了心肌特性e(t)与心脏收缩同步s(t)之间的关系。

We investigated how myocardial mechanical synchrony influences ventricular contractility. To dissociate the myocardial time varying property E(t) and synchrony s(t) of cardiac contraction, we hypothesized that the time varying ventricular property e(t) can be approximated by a convolution of s(t) and e(t). To examine the hypothesis, we determined e(t) of isolated crosscirculated canine heart using a time domain direct deconvolution technique. The result indicated that a(t) derived from the early phase of contraction has longer duration of the mechanical contraction than that obtained from the late phase of contraction. Since the electrical depolarizaion propagates from the endocardium to epicardium, this is to say that the duration of the mechanical contraction would be longer in the endocardial myocardium than epicardial myocardium. This was evidenced by the fact that the mass pacing of the heart resulted in lower contractility than atrial pacing.If the convolutional model is sound, we should be able to obtain e(t) even from the heart in ventricular fibrillation. We Fourier analyzed left ventricular pressure of fibrillating heart and deconvolved it using a homomorphic deconvolution technique. The e(t) thus determined matched reasonably well with that obtained by the time domain deconvolution. Therefore the convolutional model of the left ventricle appears to integrally characterize the relationship between myocardial property e(t) and synchrony s(t) of cardiac contraction.