Right ventricular outflow tract pacing: practical and beneficial. A 9-year experience of 460 consecutive implants.

BACKGROUND

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.

METHODS

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.

RESULTS

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.