Vlay Stephen C
Stony Brook Arrhythmia Study and Sudden Death Prevention Center, Division of Cardiology, Department of Medicine, Stony Brook University, New York, USA.
Pacing Clin Electrophysiol. 2006 Oct;29(10):1055-62. doi: 10.1111/j.1540-8159.2006.00498.x.
Pacing from the right ventricular apex (RVA) in patients with ventricular dysfunction has been identified as a possible contributor to deterioration of ventricular function. Therefore, alternative pacing sites such as the right ventricular outflow tract (RVOT) are receiving intensified scrutiny. An unresolved question is whether technical, procedural, and stability issues are comparable for the RVA and the RVOT.
This report details 460 consecutive ventricular pacing lead implants with the primary intended site in the RVOT. Patients were evaluated for success, complication rates, and followed-up for stability of pacing parameters. The total patient implant population included 300 male and 170 female patients with a mean age of 70.6 years. Ten patients were excluded from the analysis, since there was a primary indication and intention to implant in the RVA, leaving a total of 460 patients for analysis. The indications for pacing were symptomatic bradycardia due to any cause and/or Mobitz II or complete heart block. There was no clinical evidence of heart failure in 420 patients. In 40 patients with heart failure, the indication for pacing was cardiac resynchronization therapy using the RVOT as an alternate site when pacing from a branch vein of the coronary sinus was not possible. Outcome information was obtained from the implanter's clinic.
The overall success rate in the RVOT was 84% over the total 9-year period with a 92% success rate in the last 4(1/2) years, using the RVOT technique described. At 20 months in a subgroup comparison of RVOT and RVA implants, there was no significant difference in pacing threshold, R-wave sensing, or pacing lead impedance. Dislodgment occurred in only 1 of 460 patients. Reasons for failure to implant in the RVOT include inability to find a stable position with adequate pacing and sensing thresholds (related to anatomy, scarred myocardium, pulmonary hypertension, tricuspid regurgitation), hemodynamic instability limiting time for implant, and a learning curve. Long-term stability and lead performance were excellent, and certain acute and chronic complications of RV pacing did not occur.
已确定心室功能不全患者从右心室心尖部（RVA）起搏可能是导致心室功能恶化的一个因素。因此，诸如右心室流出道（RVOT）等替代起搏部位正受到更密切的审视。一个尚未解决的问题是，RVA和RVOT在技术、操作及稳定性方面的问题是否具有可比性。
本报告详细介绍了460例连续进行的心室起搏导线植入术，主要植入部位为RVOT。对患者的植入成功率、并发症发生率进行评估，并对起搏参数的稳定性进行随访。患者植入总数包括300例男性和170例女性，平均年龄70.6岁。10例患者被排除在分析之外，因为其主要指征和意图是植入RVA，最终共有460例患者可供分析。起搏指征为任何原因引起的有症状心动过缓和/或莫氏Ⅱ型或完全性心脏传导阻滞。420例患者无心力衰竭的临床证据。在40例心力衰竭患者中，起搏指征为当无法从冠状静脉窦分支静脉起搏时，将RVOT作为替代部位进行心脏再同步治疗。结局信息来自植入者的诊所。
在整个9年期间，使用所述RVOT技术，RVOT的总体成功率为84%，在最后4.5年的成功率为92%。在RVOT和RVA植入的亚组比较中，20个月时起搏阈值、R波感知或起搏导线阻抗无显著差异。460例患者中仅1例发生导线脱位。未能在RVOT植入的原因包括无法找到起搏和感知阈值合适的稳定位置（与解剖结构、心肌瘢痕、肺动脉高压、三尖瓣反流有关）、血流动力学不稳定限制了植入时间以及存在学习曲线。长期稳定性和导线性能良好，且未发生右心室起搏的某些急慢性并发症。
