Verrier R L, Nearing B D
Department of Pharmacology, Georgetown University School of Medicine, Washington, D.C. 20007.
J Cardiovasc Electrophysiol. 1994 May;5(5):445-61. doi: 10.1111/j.1540-8167.1994.tb01184.x.
Substantial evidence indicates that T wave alternans is an intrinsic property of ischemic myocardium. The electrophysiologic basis appears to be spatial and temporal heterogeneity of repolarization resulting from changes in action potential morphology rather than in activation sequence. Ischemia-induced changes in postrepolarization refractoriness and depressed electrical restitution of action potential duration have also been implicated. The main underlying ionic basis for T wave alternans during coronary occlusion appears to be derangements in intracellular cycling of calcium. Accumulation of potassium in the extracellular space adjoining ischemic cells and disruption in electrogenic sodium-calcium exchange may also be involved. In humans, T wave alternans has been observed in Prinzmetal's and classical angina, angioplasty, and bypass graft occlusion. Under these conditions associated with acute myocardial ischemia, alternans is restricted to the ischemic zone, and alternation in action potential morphology is an underlying factor. Recently, repolarization alternans has been shown to be a statistically significant predictor of the results of electrophysiologic testing and arrhythmia-free survival in individuals with and without organic heart disease. Collectively, these observations provide a rationale for quantitation of T wave alternans magnitude for assessment of vulnerability to life-threatening ventricular arrhythmias both in response to and independent of the effects of myocardial ischemia.
大量证据表明，T波交替是缺血心肌的一种内在特性。其电生理基础似乎是动作电位形态改变而非激活顺序改变导致的复极在空间和时间上的异质性。缺血引起的复极后不应期改变以及动作电位时程的电恢复能力降低也与之有关。冠状动脉闭塞期间T波交替的主要潜在离子基础似乎是细胞内钙循环紊乱。缺血细胞相邻的细胞外空间钾离子积聚以及电致钠钙交换中断也可能参与其中。在人类中，已在变异型心绞痛和典型心绞痛、血管成形术以及旁路移植闭塞中观察到T波交替。在这些与急性心肌缺血相关的情况下，交替仅限于缺血区，动作电位形态的交替是一个潜在因素。最近，复极交替已被证明是有或无器质性心脏病个体电生理测试结果和无心律失常生存期的统计学显著预测指标。总体而言，这些观察结果为定量T波交替幅度提供了理论依据，以评估无论是在心肌缺血反应中还是独立于心肌缺血影响时发生危及生命的室性心律失常的易感性。
