Dvir Hila, Zlochiver Sharon
Department of Biomedical Engineering, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel.
Annu Int Conf IEEE Eng Med Biol Soc. 2011;2011:685-8. doi: 10.1109/IEMBS.2011.6090154.
The physiological heart rate presents a stochastic behavior known as heart rate variability (HRV). In this framework the influence of HRV on the action potential duration (APD) of the atrial myocyte is analyzed in a computer model. We have found that introducing HRV into the myocyte action potential model decreases the APD of the extra beat S2 in an S1-S2 protocol compared to constant heart rate. A possible theoretical explanation for this is also presented and is derived from switched systems theory. It is suggested to consider the myocyte action potential phase 4 and phase 2 as two operation modes of a switching system and analyze the stability of switching between them. Since random switching is known to have a stabilization effect on a switching system, this might explain why HRV has a stabilization effect on the myocyte APD restitution. Implications of this finding include reduced system stability for conditions with low HRV. A possible application for this phenomenon regards artificial pacemakers, where a preset added HRV is predicted to reduce susceptibility to arrhythmias.
生理心率呈现出一种被称为心率变异性（HRV）的随机行为。在此框架下，在一个计算机模型中分析了HRV对心房肌细胞动作电位时程（APD）的影响。我们发现，与恒定心率相比，将HRV引入肌细胞动作电位模型会降低S1-S2方案中额外搏动S2的APD。对此还给出了一种可能的理论解释，该解释源自切换系统理论。建议将肌细胞动作电位的4期和2期视为一个切换系统的两种运行模式，并分析它们之间切换的稳定性。由于已知随机切换对切换系统有稳定作用，这可能解释了为什么HRV对肌细胞APD恢复有稳定作用。这一发现的影响包括低HRV情况下系统稳定性降低。这一现象的一个可能应用涉及人工起搏器，预计预设增加的HRV可降低心律失常的易感性。
