Ridler Marc, McQueen David M, Peskin Charles S, Vigmond Edward
Fac. of Electr. Eng., Calgary Univ., Alta.
Conf Proc IEEE Eng Med Biol Soc. 2006;2006:3978-81. doi: 10.1109/IEMBS.2006.260522.
Atrial fibrillation (AF) is the most common cardiac arrhythmia. It is characterized by rapid and disorganized electrical activity in the atria. Atrial arrhythmias can be triggered from an ectopic focus, i.e., an abnormal impulse originating in an area other than the sinus node, generating reentrant waves. The regional ionic heterogeneities found in the atria cause a gradual shortening of the action potential duration (APD) with increased distance from the sinoatrial node. It is generally thought that the only electrophysiological consequence of the spatial dispersion of cardiac action potentials (AP) is the enhancement of reentry. This paper investigates the effect of a gradient in APD on arrhythmogenesis via computer simulations. A gradient of ionic properties was introduced into a computationally efficient computer model of the canine atria to produce a smooth distribution of APDs. The window of vulnerability for ectopic beat-induction of reentry was determined for both left atrium (LA) and the right atrium (RA) stimulation, with and without an APD gradient. The shortened windows of vulnerability in the RA, due to the addition of the APD gradient, suggests a protective mechanism against AF. The left atrial window of vulnerability was slightly longer from ionic dispersion.
心房颤动（AF）是最常见的心律失常。其特征是心房内快速且紊乱的电活动。房性心律失常可由异位起搏点触发，即起源于窦房结以外区域的异常冲动，产生折返波。心房中发现的区域离子异质性导致动作电位时程（APD）随着与窦房结距离的增加而逐渐缩短。一般认为心脏动作电位（AP）空间离散的唯一电生理后果是折返增强。本文通过计算机模拟研究了APD梯度对心律失常发生的影响。将离子特性梯度引入犬心房的高效计算模型中，以产生APD的平滑分布。在有和没有APD梯度的情况下，分别测定了左心房（LA）和右心房（RA）刺激诱发折返性异位搏动的易损窗口。由于添加了APD梯度，RA中缩短的易损窗口提示了一种针对AF的保护机制。由于离子离散，左心房的易损窗口略长。
