Gorgels A P, De Wit B, Beekman H D, Dassen W R, Wellens H J
Pacing Clin Electrophysiol. 1986 Nov;9(6):842-59. doi: 10.1111/j.1540-8159.1986.tb06634.x.
During digitalis-induced, sustained, monomorphic ventricular tachycardia, programmed electrical stimulation was performed and the effect on the first post-pacing QRS morphology was determined. Ventricular tachycardia was induced in nine conscious dogs with chronic complete atrioventricular block by administering digoxin i.v. 0.1 mg/kg given in 1-1 1/2 hour. Spontaneous ventricular tachycardia most frequently had a right bundle branch block morphology and an extreme left axis suggesting an origin in the apex of the left ventricle. Less frequently, a left bundle branch block-like configuration with an intermediate axis was observed, compatible with an origin in the basal part of the right ventricle. Following pacing close to one of these predilection sites, the first post-pacing QRS morphology suggested an origin close to the site of stimulation. Pacing distant from these predilection sites resulted in fusion complexes between electrical activation from these predilection sites and the stimulation site. The amount of fusion depended on interstimulus interval and the number of stimuli. Long interstimulus intervals and few stimuli induced a QRS complex similar to that of the spontaneous tachycardia. The faster and longer the stimulation train, the more the QRS complex became similar to the paced QRS complex. Similar findings were also observed on decreasing the last paced interval only. Our findings suggest that triggered activity is the underlying mechanism for the first post-pacing QRS complex. QRS configuration and the relation between the R-R interval and QRS configuration during tachycardia suggest that triggered activity is also the mechanism for the spontaneously occurring ventricular tachycardia during digitalis intoxication. These observations may have important clinical implications.
在洋地黄引起的持续性单形性室性心动过速期间，进行了程控电刺激，并确定了其对起搏后首个QRS波形态的影响。通过静脉注射地高辛0.1mg/kg（在1 - 1.5小时内给予），在9只患有慢性完全性房室传导阻滞的清醒犬中诱发室性心动过速。自发性室性心动过速最常见的形态为右束支传导阻滞，电轴极度左偏，提示起源于左心室心尖部。较少见的是，观察到类似左束支传导阻滞的形态，电轴居中，这与起源于右心室基底部相符。在靠近这些偏好部位之一进行起搏后，起搏后首个QRS波形态提示起源靠近刺激部位。远离这些偏好部位进行起搏会导致这些偏好部位的电激动与刺激部位之间形成融合波。融合的程度取决于刺激间期和刺激次数。长刺激间期和少量刺激会诱发与自发性心动过速相似的QRS波群。刺激序列越快且越长，QRS波群就越接近起搏的QRS波群。仅缩短最后一个起搏间期时也观察到了类似的结果。我们的研究结果表明，触发活动是起搏后首个QRS波群的潜在机制。心动过速期间的QRS形态以及R - R间期与QRS形态之间的关系表明，触发活动也是洋地黄中毒期间自发性室性心动过速的机制。这些观察结果可能具有重要的临床意义。
