Vijayaraman Pugazhendhi, Kok Lai Chow, Wood Mark A, Ellenbogen Kenneth A
Division of Cardiac Electrophysiology, Geisinger Wyoming Valley Medical Center, MC 36-10, 1000 E. Mountain Boulevard, Wilkes-Barre, PA 18711, USA.
Heart Rhythm. 2006 Mar;3(3):268-72. doi: 10.1016/j.hrthm.2005.11.014.
Successful radiofrequency (RF) ablation of typical, isthmus-dependent atrial flutter requires establishment and confirmation of bidirectional conduction block across the cavotricuspid isthmus. Low atrial pacing usually is performed from the bipoles of the 20-pole Halo catheter, septal and lateral to the cavotricuspid isthmus ablation line. However, occasionally this is difficult because of high pacing thresholds and/or saturation of the atrial electrograms recorded near the pacing catheter.
The purpose of this study was to assess if right ventricular (RV) pacing and resulting retrograde atrial activation can be used to assess conduction block from the septum to the lateral wall in a clockwise direction.
Thirty-five consecutive male patients (mean age 64 +/- 10 years; mean ejection fraction 42 +/- 13%; mean left atrial dimension 44 +/- 6 mm) with typical isthmus-dependent atrial flutter were studied. The following electrophysiology catheters were used: 20-pole catheter along the tricuspid annulus, quadripolar catheters at the His and/or RV apex, and 8-mm ablation catheter. Following RF ablation of the cavotricuspid isthmus, bidirectional conduction block was confirmed in all 35 patients by pacing at a cycle length of 600 ms from bipoles septal and lateral to the cavotricuspid isthmus ablation line. Conduction times from pacing artifact to adjacent bipolar atrial electrograms and reversal of atrial activation pattern were analyzed. RV pacing was performed and retrograde atrial activation pattern assessed. If retrograde AV nodal conduction was absent, isoproterenol was infused intravenously at 2 microg/min, and RV pacing was repeated. The conduction time between the double potentials across the cavotricuspid isthmus ablation line was measured.
Mean conduction times across the isthmus during septal (S), lateral (L), and RV pacing were 145 +/- 21 ms, 144 +/- 24 ms, and 129 +/- 20 ms, respectively. Retrograde AV nodal conduction was present in 34 of 35 patients (isoproterenol 8 patients). Evidence of conduction block by a clear change in activation pattern across the isthmus was seen during RV pacing in 33 of 35 patients with bidirectional conduction block.
RV pacing is a simple and easy maneuver that can be performed to assess isthmus conduction in most patients.
成功进行典型的、依赖峡部的心房扑动的射频消融需要建立并确认经腔静脉-三尖瓣峡部的双向传导阻滞。低位心房起搏通常通过20极Halo导管的电极在腔静脉-三尖瓣峡部消融线的间隔侧和外侧进行。然而，由于起搏阈值高和/或起搏导管附近记录的心房电图饱和，偶尔会遇到困难。
本研究的目的是评估右心室（RV）起搏及由此产生的逆行心房激动是否可用于评估从间隔到侧壁顺时针方向的传导阻滞。
对35例连续的男性患者（平均年龄64±10岁；平均射血分数42±13%；平均左心房内径44±6mm）进行典型的依赖峡部的心房扑动研究。使用以下电生理导管：沿三尖瓣环的20极导管、希氏束和/或右心室尖部的四极导管以及8mm消融导管。在对腔静脉-三尖瓣峡部进行射频消融后，通过从腔静脉-三尖瓣峡部消融线的间隔侧和外侧电极以600ms的周期长度起搏，在所有35例患者中均确认了双向传导阻滞。分析了从起搏伪迹到相邻双极心房电图的传导时间以及心房激动模式的逆转。进行右心室起搏并评估逆行心房激动模式。如果不存在逆行房室结传导，则以2μg/min的速度静脉注射异丙肾上腺素，并重复右心室起搏。测量经腔静脉-三尖瓣峡部消融线双电位之间的传导时间。
间隔（S）、外侧（L）和右心室起搏时经峡部的平均传导时间分别为145±21ms、144±24ms和129±20ms。35例患者中有34例存在逆行房室结传导（8例使用异丙肾上腺素）。在35例双向传导阻滞患者中的33例右心室起搏期间，可见峡部激活模式明显改变的传导阻滞证据。
右心室起搏是一种简单易行的操作，可用于评估大多数患者的峡部传导。
