Hazim Azzam, Belhamadia Youssef, Dubljevic Stevan
Department of Biomedical Engineering, University of Alberta, Edmonton, Alberta, Canada.
Department of Mathematics and Statistics, American University of Sharjah, Sharjah, United Arab Emirates.
Biophys J. 2021 Jan 5;120(1):109-121. doi: 10.1016/j.bpj.2020.11.018. Epub 2020 Nov 26.
The deformation of the heart tissue due to the contraction can modulate the excitation, a phenomenon referred to as mechanoelectrical feedback (MEF), via stretch-activated channels. The effects of MEF on the electrophysiology at high pacing rates are shown to be proarrhythmic in general. However, more studies need to be done to elucidate the underlying mechanism. In this work, we investigate the effects of MEF on cardiac alternans, which is an alternation in the width of the action potential that typically occurs when the heart is paced at high rates, using a biophysically detailed electromechanical model of cardiac tissue. We observe that the transition from spatially concordant alternans to spatially discordant alternans, which is more arrhythmogenic than concordant alternans, may occur in the presence of MEF and when its strength is sufficiently large. We show that this transition is due to the increase of the dispersion of conduction velocity. In addition, our results also show that the MEF effects, depending on the stretch-activated channels' conductances and reversal potentials, can result in blocking action potential propagation.
心脏组织因收缩而产生的变形可通过牵张激活通道调节兴奋，这一现象被称为机械电反馈（MEF）。一般来说，MEF对高起搏频率下电生理学的影响显示为促心律失常。然而，需要开展更多研究来阐明其潜在机制。在这项工作中，我们使用一个生物物理细节丰富的心脏组织机电模型，研究MEF对心脏交替性的影响，心脏交替性是指动作电位宽度的交替变化，通常在心脏以高频率起搏时出现。我们观察到，在存在MEF且其强度足够大时，可能会发生从空间一致交替性到空间不一致交替性的转变，后者比一致交替性更易引发心律失常。我们表明，这种转变是由于传导速度离散度的增加所致。此外，我们的结果还表明，MEF效应取决于牵张激活通道的电导和反转电位，可导致动作电位传播受阻。
