Kalman J M, Lee R J, Fisher W G, Chin M C, Ursell P, Stillson C A, Lesh M D, Scheinman M M
Department of Medicine, University of California, San Francisco 94143-0214, USA.
Circulation. 1995 Nov 15;92(10):3070-81. doi: 10.1161/01.cir.92.10.3070.
The sinus P wave arises from a pacemaker complex distributed along the crista terminalis. We investigated the feasibility of modification of sinus pacemaker function using graded applications of radiofrequency energy along the crista terminalis in dogs to achieve sinus rate control.
Modification of sinus pacemaker function (30 +/- 5% reduction in intrinsic heart rate with retention of a normal P-wave axis) was performed in 11 dogs (group 1). Total sinus pacemaker ablation (> 50% reduction in intrinsic heart rate with development of a low ectopic atrial or a junctional rhythm) was performed in 4 dogs (group 2). Intracardiac echocardiography was used to identify the crista terminalis as an anatomic marker of sinus node location. Sinus pacemaker modification caused a significant decrease in intrinsic heart rate (31% reduction, P < .001), heart rate responsiveness to isoproterenol (30% reduction, P < .0001), and average (20% reduction, P = .0002) and maximal (22% reduction, P = .0007) heart rates during 24-hour Holter monitoring. In 6 of the 11 animals, the targeted rate reduction of 30 +/- 5% was accurately achieved (mean, 31.6 +/- 4.3%; P < .001), and in the other 5, significant reduction of intrinsic heart rate was achieved but with greater variation (28.0 +/- 17.3%, P < .005). Corrected sinus node recovery time was not prolonged. After modification, earliest activation was mapped to the crista terminalis inferior to the lesion in all animals. In long-term follow-up (3.7 +/- 1.0 months), effects were maintained. After total sinus pacemaker ablation, junctional and low atrial escape pacemakers were unstable.
This study demonstrates the feasibility of modification of sinus pacemaker function for sinus rate control using catheter-based radiofrequency ablation guided by intracardiac echocardiography. This can be done while pacemaker stability and attenuated responsiveness to autonomic influences are preserved. Intracardiac echocardiography accurately defined the crista terminalis and provided a reliable means to anatomically localize catheter position in relation to the sinus node.
窦性P波起源于沿界嵴分布的起搏复合体。我们研究了在犬类动物中沿界嵴分级应用射频能量来改变窦性起搏功能以实现窦性心率控制的可行性。
对11只犬（第1组）进行了窦性起搏功能的改变（固有心率降低30±5%，同时保留正常P波电轴）。对4只犬（第2组）进行了完全性窦性起搏消融（固有心率降低>50%，并出现低位房性或交界性心律）。采用心腔内超声心动图将界嵴确定为窦房结位置的解剖学标志。窦性起搏功能改变导致固有心率显著降低（降低31%，P<.001），心率对异丙肾上腺素的反应性降低（降低30%，P<.0001），以及24小时动态心电图监测期间的平均心率（降低20%，P=.0002）和最大心率（降低22%，P=.0007）降低。在11只动物中的6只中，准确实现了目标心率降低30±5%（平均，31.6±4.3%；P<.001），在另外5只中，固有心率显著降低，但变化较大（28.0±17.3%，P<.005）。校正的窦房结恢复时间未延长。改变后，在所有动物中最早激动被标测到病变下方的界嵴处。在长期随访（3.7±1.0个月）中，效果得以维持。完全性窦性起搏消融后，交界性和低位房性逸搏起搏点不稳定。
本研究证明了在心腔内超声心动图引导下使用导管射频消融改变窦性起搏功能以控制窦性心率的可行性。在保留起搏稳定性和减弱对自主神经影响的反应性的同时可以做到这一点。心腔内超声心动图准确地界定了界嵴，并提供了一种可靠的方法来在解剖学上确定导管相对于窦房结的位置。
