Castellanos A, Portillo B, Mejias J, Leon-Portillo N, Saoudi N C, Zaman L
J Am Coll Cardiol. 1985 Dec;6(6):1431-7. doi: 10.1016/s0735-1097(85)80237-0.
An unusual case is presented in which a circus movement tachycardia incorporating an accessory pathway with long retrograde conduction time was transiently entrained. Overdrive high right atrial stimulation produced entrainment without atrial fusion since collision of anterograde and retrograde impulses took place within the accessory pathway. Tachycardia termination occurred when, at a faster pacing rate, an atrial impulse that collided in the accessory pathway was blocked at the atrioventricular (AV) node. In contrast, the entrainment seen during right ventricular apical stimulation was characterized by the occurrence of both fusion and collision within the ventricles. The tachycardia was terminated when a pure paced impulse that collided in the normal pathway was blocked in a retrograde direction in the accessory pathway. These data indicate that: 1) transient entrainment of this arrhythmia (circus movement tachycardia) can be identified by the classical criteria used to diagnose it, provided that fusion and collision occur within the ventricles; and 2) the accessory pathway is the weak link for tachycardia termination only during ventricular pacing since the AV node is the weak link during atrial stimulation.
本文介绍了一个不寻常的病例，其中包含一条具有长逆行传导时间的旁路的马戏团运动性心动过速被短暂拖带。超速右房高位刺激产生了拖带且无房融合，因为顺行和逆行冲动在旁路内发生了碰撞。当以更快的起搏频率时，在旁路内碰撞的心房冲动在房室（AV）结被阻滞，心动过速终止。相比之下，右室心尖部刺激时所见的拖带特征是在心室内同时出现融合和碰撞。当在正常路径中碰撞的纯起搏冲动在旁路中逆向被阻滞时，心动过速终止。这些数据表明：1）只要融合和碰撞发生在心室，这种心律失常（马戏团运动性心动过速）的短暂拖带可通过用于诊断它的经典标准来识别；2）仅在心室起搏期间旁路是心动过速终止的薄弱环节，因为在心房刺激期间AV结是薄弱环节。
