Implantation and follow-up of ICD leads implanted in the right ventricular outflow tract

Unipolar ICD electrodes are routinely implanted at the right ventricular apex (RVA). However, inappropriate pacing/sensing parameters and/or high DFT may limit the appropriateness of the lead's implantation at the RVA. This study examined the effects on DFT of ICD leads implanted in the RVOT, attached to the high interventricular septum as an alternate location. DFT, defibrillation impedance, and sensing and pacing characteristics were measured at the time of implantation in 28 consecutive patients. Group A consisted of 12 patients in whom the ICD implantation criteria in the RVA were not satisfied, and whose lead was placed in the RVOT. Group B consisted of 16 patients with ICD electrodes implanted at the RVA. Mean DFT in group A was 11 +/- 4 J (4.5-20 J) versus 12 +/- 6 J (4-20 J) in the group B (P = 0.58). Defibrillation impedance was 81 +/- 9 omega (69-92 omega) in group A versus 77 +/- 15 omega) (46-93 omega) in group B (P = 0.43). R wave amplitude, slew rate, pacing threshold, and pacing impedance were comparable in both groups. In the perioperative period, the electrode needed to be repositioned in two patients from group A. There was no further dislodgment of RVOT defibrillation leads or other lead related complications during a follow-up of 23 +/- 9 months. The placement of ICD leads in the RVOT is an alternative to the RVA position. However, active-fixation ICD leads should be considered to limit the risk of electrode dislodgment.