Ravelli Flavia
Department of Physics, University of Trento and ITC-irst, Via Sommarive 14, 38050, Povo-Trento, Italy.
Prog Biophys Mol Biol. 2003 May-Jul;82(1-3):137-49. doi: 10.1016/s0079-6107(03)00011-7.
Atrial fibrillation frequently occurs under conditions associated with atrial dilatation suggesting a role of mechano-electric feedback in atrial arrhythmogenesis. Although atrial arrhythmias may be due both to abnormal focal activity and reentrant mechanisms, the majority of sustained atrial arrhythmias have been ascribed to reentrant activity. Atrial stretch may contribute to focal arrhythmias by inducing afterdepolarizations and to reentrant arrhythmias by increasing the atrial surface, by shortening the refractory period and/or slowing the conduction velocity and by increasing their spatial dispersion. Experimental and clinical studies have demonstrated that changes in mechanical loading conditions may modulate the electrophysiological properties of the atria. These studies have, for the most part, involved the effects of acute stretch on atrial refractoriness. While studies in humans and intact animals yield divergent results due to the variety of loading conditions and neurohumoral influences, experimental studies in isolated preparations clearly show that atrial refractory period and action potential duration at early levels of repolarization shorten by acute atrial dilatation. Both experimental and human studies have shown that acute atrial stretch is arrhythmogenic and may induce triggered premature beats and atrial fibrillation.
心房颤动常发生于与心房扩张相关的情况下，提示机械电反馈在心房心律失常发生机制中起作用。虽然房性心律失常可能是由于异常的局灶性活动和折返机制，但大多数持续性房性心律失常被认为是由折返活动引起的。心房牵张可能通过诱发后去极化导致局灶性心律失常，并通过增加心房表面积、缩短不应期和/或减慢传导速度以及增加其空间离散度导致折返性心律失常。实验和临床研究表明，机械负荷条件的改变可能调节心房的电生理特性。这些研究大多涉及急性牵张对心房不应期的影响。虽然由于负荷条件和神经体液影响的多样性，人类和完整动物的研究结果存在差异，但离体标本的实验研究清楚地表明，急性心房扩张会使心房不应期和复极早期的动作电位时程缩短。实验和人体研究均表明，急性心房牵张具有致心律失常作用，可能诱发触发早搏和心房颤动。
