Otani Niels F
Department of Mathematical Sciences, Rochester Institute of Technology, Rochester, New York 14623, USA.
Chaos. 2017 Sep;27(9):093935. doi: 10.1063/1.5003250.
The beat-to-beat alternation in action potential durations (APDs) in the heart, called APD alternans, has been linked to the development of serious cardiac rhythm disorders, including ventricular tachycardia and fibrillation. The length of the period between action potentials, called the diastolic interval (DI), is a key dynamical variable in the standard theory of alternans development. Thus, methods that control the DI may be useful in preventing dangerous cardiac rhythms. In this study, we examine the dynamics of alternans during controlled-DI pacing using a series of single-cell and one-dimensional (1D) fiber models of alternans dynamics. We find that a model that combines a so-called memory model with a calcium cycling model can reasonably explain two key experimental results: the possibility of alternans during constant-DI pacing and the phase lag of APDs behind DIs during sinusoidal-DI pacing. We also find that these results can be replicated by incorporating the memory model into an amplitude equation description of a 1D fiber. The 1D fiber result is potentially concerning because it seems to suggest that constant-DI control of alternans can only be effective over only a limited region in space.
心脏动作电位时程（APD）的逐搏交替现象，即APD交替，与包括室性心动过速和颤动在内的严重心律失常的发生有关。动作电位之间的间期长度，即舒张期间期（DI），是交替现象发生标准理论中的一个关键动态变量。因此，控制DI的方法可能有助于预防危险的心律。在本研究中，我们使用一系列交替现象动力学的单细胞和一维（1D）纤维模型，研究了在控制DI起搏期间交替现象的动力学。我们发现，一个将所谓的记忆模型与钙循环模型相结合的模型，可以合理地解释两个关键实验结果：恒DI起搏期间出现交替现象的可能性，以及正弦DI起搏期间APD相对于DI的相位滞后。我们还发现，将记忆模型纳入1D纤维的振幅方程描述中，可以重现这些结果。1D纤维的结果可能令人担忧，因为它似乎表明，对交替现象的恒DI控制可能仅在有限的空间区域内有效。
