Distribution of Electromechanical Delay in the Heart: Insights from a Three-Dimensional Electromechanical Model
Distribution of Electromechanical Delay in the Heart: Insights from a Three-Dimensional Electromechanical Model
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DOI：
10.1016/j.bpj.2010.05.028
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发表时间：
2010-08-04
影响因子：
3.4
通讯作者：
Trayanova, N. A.
中科院分区：
文献类型：
--
作者：
Gurev, V.;Constantino, J.;Trayanova, N. A.
在完整心脏中，电机械延迟（EMD）的分布，局部去极化和心肌细胞缩短开始之间的时间间隔，取决于负荷条件。然而，EMD在整个心脏中的分布仍然未知，因为目前的实验技术无法评估三维心脏机电行为。本研究的目的是确定三维EMD分布在完整的心室窦性心律（SR）和心外膜起搏（EP），通过使用一个新的，据我们所知，机电模型的兔子心室，结合了生物物理表示的肌丝动力学。此外，我们的目的是确定的机制，具体的三维EMD分布的基础。结果表明，在这两种情况下，三维EMD分布是不均匀的。在SR期间，心外膜处的EMD比心内膜处的长，并且靠近基部的EMD比顶端的大。电生理后，三维EMD分布明显不同，并随起搏频率的变化而变化。对于SR和EP，晚期去极化区域的特征在于由早期去极化区域的收缩引起的显著肌纤维预拉伸。这种预拉伸延迟了肌纤维缩短的发生，并导致较长的EMD，从而产生不均匀的三维EMD分布。
In the intact heart, the distribution of electromechanical delay (EMD), the time interval between local depolarization and myocyte shortening onset, depends on the loading conditions. The distribution of EMD throughout the heart remains, however, unknown because current experimental techniques are unable to evaluate three-dimensional cardiac electromechanical behavior. The goal of this study was to determine the three-dimensional EMD distributions in the intact ventricles for sinus rhythm (SR) and epicardial pacing (EP) by using a new, to our knowledge, electromechanical model of the rabbit ventricles that incorporates a biophysical representation of myofilament dynamics. Furthermore, we aimed to ascertain the mechanisms that underlie the specific three-dimensional EMD distributions. The results revealed that under both conditions, the three-dimensional EMD distribution is nonuniform. During SR, EMD is longer at the epicardium than at the endocardium, and is greater near the base than at the apex. After EP, the three-dimensional EMD distribution is markedly different; it also changes with the pacing rate. For both SR and EP, late-depolarized regions were characterized with significant myofiber prestretch caused by the contraction of the early-depolarized regions. This prestretch delays myofiber-shortening onset, and results in a longer EMD, giving rise to heterogeneous three-dimensional EMD distributions.