Yan Gan-Xin, Lankipalli Ramarao S, Burke James F, Musco Simone, Kowey Peter R
Main Line Health Heart Center, Wynnewood, Pennsylvania 19096, USA.
J Am Coll Cardiol. 2003 Aug 6;42(3):401-9. doi: 10.1016/s0735-1097(03)00713-7.
Ventricular repolarization components on the surface electrocardiogram (ECG) include J (Osborn) waves, ST-segments, and T- and U-waves, which dynamically change in morphology under various pathophysiologic conditions and play an important role in the development of ventricular arrhythmias. Our primary objective in this review is to identify the ionic and cellular basis for ventricular repolarization components on the body surface ECG under normal and pathologic conditions, including a discussion of their clinical significance. A specific attempt to combine typical clinical ECG tracings with transmembrane electrical recordings is made to illustrate their logical linkage. A transmural voltage gradient during initial ventricular repolarization, which results from the presence of a prominent transient outward K(+) current (I(to))-mediated action potential (AP) notch in the epicardium, but not endocardium, manifests as a J-wave on the ECG. The J-wave is associated with the early repolarization syndrome and Brugada syndrome. ST-segment elevation, as seen in Brugada syndrome and acute myocardial ischemia, cannot be fully explained by using the classic concept of an "injury current" that flows from injured to uninjured myocardium. Rather, ST-segment elevation may be largely secondary to a loss of the AP dome in the epicardium, but not endocardium. The T-wave is a symbol of transmural dispersion of repolarization. The R-on-T phenomenon (an extrasystole originating on the T-wave of a preceding ventricular beat) is probably due to transmural propagation of phase 2 re-entry or phase 2 early after depolarization that could potentially initiate polymorphic ventricular tachycardia or fibrillation.
体表心电图（ECG）上的心室复极成分包括J（奥斯本）波、ST段以及T波和U波，这些成分在各种病理生理条件下形态会动态变化，并在室性心律失常的发生发展中起重要作用。本综述的主要目的是确定正常和病理条件下体表ECG上心室复极成分的离子和细胞基础，包括讨论它们的临床意义。我们将典型临床ECG描记图与跨膜电记录相结合，以说明它们之间的逻辑联系。心室初始复极期间的跨壁电压梯度是由心外膜而非心内膜中突出的瞬时外向钾电流（I(to)）介导的动作电位（AP）切迹所致，在ECG上表现为J波。J波与早期复极综合征和Brugada综合征相关。Brugada综合征和急性心肌缺血中出现的ST段抬高，不能用从受损心肌流向未受损心肌的“损伤电流”这一经典概念来完全解释。相反，ST段抬高可能主要继发于心外膜而非心内膜AP圆顶的丧失。T波是复极跨壁离散的标志。R波落在T波上现象（室性早搏起源于前一个心室搏动的T波）可能是由于2相折返或2相早期后除极的跨壁传播，这可能引发多形性室性心动过速或颤动。
