间歇依赖性长QT间期综合征伴扭转型室性心动过速的电生理探讨

THE ELECTROPHYSIOLOGY OF PAUSE-DEPENDENT LONG QT INTERVAL SYNDROME AND TORSADE DE POINTS VENTRICULAR TACHYCARDIA

长ＱＴ间期伴扭转型室性心动过速（ＴｄＰ）是临床上常见的严重心律失常。ＴｄＰ的发生机制已有研究，表明可能与触发机制有关。本文对３例不同病因的长ＱＴ间期综合征（ＬＯＴＳ）伴ＴｄＰ的电生理和心内膜单相动作电位记录进行了研究。观察到如下特点：①心室刺激（程序或递增刺激）结合异丙肾上腺素静脉注射均不能诱发室性心律失常；②全部患者心电图上均能记录到巨大Ｕ波；③２例患者，在右心室内膜单相动作电位复极化［３］相期记录到一个驼峰形波，即为后去极化（ＥＡＤ），该驼峰形波与体表心电图上巨大Ｕ波同步发生。本研究表明ＥＡＤ在ＬＱＴＳ伴ＴｄＰ的发生中可能起重要作用。

Torsade de points (TdP) with long QT interval is a common serious arrhythmia. The mechanism of TdP is not clear. The electrophysiology and endocardial monophasic action potential (MAP) recording in three patients with long QT interval syndrome (LQTS) and TdP of different etiology were studied. The following features were observed: (1) Ventricular arrhythmias could not be induced by ventricular endocardial stimuli (3 cases) and i. v. isoproterenol (2 cases); (2) Large u waves were recorded in three patients with LQTSTdP on the ECG; (3) In two cases, hump waves (early afterdepolarization, EAD) on the repolarization 3 phase of MAP corresponding to the u wave of surface ECG were recorded. This study showed that EAD may play a role in the genesis of LQTS-TdP.