Quintal R, Dhurandhar R W, Jain R K
J Electrocardiol. 1984 Apr;17(2):205-8. doi: 10.1016/s0022-0736(84)81098-5.
Ventricular fibrillation has been only rarely observed as a complication of cardiac pacing after the advent of demand pacemakers. Automatic AV sequential pacing (DDD) may provide the setting for ventricular fibrillation in patients with junctional rhythms. In this report we present two patients with implanted DDD pacemakers in whom ventricular pacemaker spikes were seen occurring on top of the T wave during episodes of junctional rhythm. This apparent lack of sensing of QRS complexes does not represent pacemaker malfunction, but rather, is the result of physiologic lack of sensing (blanking) which occurs 56 to 100 msec. following the output of the atrial and ventricular channels. During junctional rhythm when the atrial spike occurs at the beginning of a QRS complex the ventricular channel is blanked and does not sense the intrinsic ventricular activity and thus, ventricular output occurs during repolarization. Increasing the maximum pacemaker rate and decreasing the AV delay will reduce the chance occurrence of this phenomenon.
自按需起搏器问世以来，心室颤动作为心脏起搏的并发症仅很少见。房室顺序自动起搏（DDD）可能为交界性心律患者发生心室颤动提供条件。在本报告中，我们介绍了两名植入DDD起搏器的患者，在交界性心律发作期间，可见心室起搏尖峰出现在T波之上。这种对QRS波群明显缺乏感知并不代表起搏器故障，而是生理上缺乏感知（消隐）的结果，这发生在心房和心室通道输出后56至100毫秒。在交界性心律时，当心房尖峰出现在QRS波群开始时，心室通道被消隐，无法感知心室的固有活动，因此心室输出发生在复极化期间。提高起搏器最大频率并缩短房室延迟将减少这种现象发生的机会。
