Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Chaos. 2020 Oct;30(10):103122. doi: 10.1063/5.0022066.
Cardiac alternans, beat-to-beat alternations in action potential duration, is a precursor to fatal arrhythmias such as ventricular fibrillation. Previous research has shown that voltage driven alternans can be suppressed by application of a constant diastolic interval (DI) pacing protocol. However, the effect of constant-DI pacing on cardiac cell dynamics and its interaction with the intracellular calcium cycle remains to be determined. Therefore, we aimed to examine the effects of constant-DI pacing on the dynamical behavior of a single-cell numerical model of cardiac action potential and the influence of voltage-calcium (V-Ca) coupling on it. Single cell dynamics were analyzed in the vicinity of the bifurcation point using a hybrid pacing protocol, a combination of constant-basic cycle length (BCL) and constant-DI pacing. We demonstrated that in a small region beneath the bifurcation point, constant-DI pacing caused the cardiac cell to remain alternans-free after switching to the constant-BCL pacing, thus introducing a region of bistability (RB). The size of the RB increased with stronger V-Ca coupling and was diminished with weaker V-Ca coupling. Overall, our findings demonstrate that the application of constant-DI pacing on cardiac cells with strong V-Ca coupling may induce permanent changes to cardiac cell dynamics increasing the utility of constant-DI pacing.
心脏电交替，即动作电位时程的逐搏交替，是致命性心律失常（如心室颤动）的前兆。先前的研究表明，通过应用恒定舒张期（DI）起搏方案可以抑制电压驱动的电交替。然而，恒定-DI 起搏对心脏细胞动力学的影响及其与细胞内钙循环的相互作用仍有待确定。因此，我们旨在研究恒定-DI 起搏对心脏动作电位单细胞数值模型动力学行为的影响，以及电压-钙（V-Ca）耦联对其的影响。使用混合起搏方案（恒定基本周期长度（BCL）和恒定-DI 起搏的组合）在分岔点附近分析单细胞动力学。我们证明，在分岔点下方的一个小区域内，恒定-DI 起搏导致心脏细胞在切换到恒定-BCL 起搏后保持无电交替，从而引入双稳定性区域（RB）。RB 的大小随 V-Ca 耦合增强而增加，随 V-Ca 耦合减弱而减小。总的来说，我们的研究结果表明，在具有强 V-Ca 耦合的心脏细胞上应用恒定-DI 起搏可能会导致心脏细胞动力学的永久性变化，从而增加恒定-DI 起搏的效用。
