Cellular basis for the normal T wave and the electrocardiographic manifestations of the long-QT syndrome
Cellular basis for the normal T wave and the electrocardiographic manifestations of the long-QT syndrome
复制标题
DOI：
10.1161/01.cir.98.18.1928
复制
发表时间：
1998-11-03
期刊：
影响因子：
37.8
通讯作者：
Antzelevitch, C
中科院分区：
文献类型：
--
作者：
Yan, GX;Antzelevitch, C
背景：本研究采用犬左心室楔形动脉灌注法，探讨了基线和长QT间期(LQT)条件下T波的细胞学基础，这种方法允许细胞跨膜和心电图事件在时间上直接相关。方法和结果浮动微电极从心外膜同时记录跨膜动作电位。M区和心内膜部位或心内膜下浦肯野纤维。同时记录跨壁心电信号。在基线和LQT条件下，心外膜动作电位最早复极的复极与T波的峰值一致，M细胞的复极最后复极与T波的结束一致。因此，最长M细胞的动作电位时程决定了QT间期，T峰T末间期可作为复极跨室壁离散度的指标。浦肯野纤维的复极持续时间超过M细胞，但不能记录在心电图上。T波的形态似乎是由于在心室动作电位的2相和3相期间，沿着M区两侧的电压梯度流下的电流。这些相反力量之间的相互作用决定了T波的高度以及T波上升或下降分支被中断的程度，从而在LQT条件下产生分叉的T波和“明显的T-U复合波”。在dl-sotalol的存在下，自发和刺激诱发的多形性室性心动过速(TDP)具有尖端扭转性室性心动过速(TDP)的特征。结论--我们的结果提供了第一个直接证据，即心外膜与M区和心内膜与M区之间的相反电压梯度对正常情况下心电图T波的记录以及在LQT条件下观察到的T波和长QT间期的增宽或分叉的T波和长QT间期有显著贡献。我们的数据表明，在后天或先天性LQT中观察到的“病理生理U”波更有可能是T波中断的第二个分量，并支持用T2代替U来描述这一事件。
Background-This study probes the cellular basis for the T wave under baseline and long-QT (LQT) conditions using an arterially perfused canine left ventricular (LV) wedge preparation, which permits direct temporal correlation of cellular transmembrane and ECG events.Methods and Results-Floating microelectrodes were used to record transmembrane action potentials (APs) simultaneously from epicardial. M-region, and endocardial sites or subendocardial Purkinje fibers. A transmural ECG was recorded concurrently. Under baseline and LQT conditions, repolarization of the epicardial action potential, the earliest to repolarize, coincided with the peak of the T wave, repolarization of the M cells, the last to repolarize, coincided with the end of the T wave. Thus, the action potential duration (APD) of the longest M cells determine the QT interval and the T-peak-T-end interval serves as an index of transmural dispersion of repolarization. Repolarization of Purkinje fibers outlasted that of the M cell but failed to register on the ECG. The morphology of the T wave appeared to be due to currents flowing down voltage gradients on either side of the M region during phase 2 and phase 3 of the ventricular action potential. The interplay between these opposing forces determined the height of the T wave as well as the degree to which the ascending or descending limb of the T wave was interrupted, giving rise to bifurcated T waves and "apparent T-U complexes" under LQT conditions. Spontaneous and stimulation-induced polymorphic ventricular tachycardia with characteristics of torsade de pointes (TdP) developed in the presence of dl-sotalol.Conclusions-Our results provide the first direct evidence that opposing voltage gradients between epicardium and the M region and endocardium and the M region contribute prominently to the inscription of the ECG T wave under normal conditions and to the widened or bifurcated T wave and long-QT interval observed under LQT conditions, Our data suggest that the "pathophysiological U" wave observed in acquired or congenital LQTS is more likely to be a second component of an interrupted T wave, and argue for use of the term T2 in place of U to describe this event.