Clinical Experience with Passive-Fixation Coradial Bipolar Endocardial Pacing Leads

Bipolar, transvenous, passive-fixation leads (ThinLine(tm) Sulzer Intermedics Inc., Angleton, TX, USA) incorporating coradial individually coated conductor coils, and a redundant external 55D polyurethane insulation sheath were developed. The diameter of the new leads (< 5 FT) is in the range of available unipolar leads and is considerably smaller than conventional bipolar pacing leads. From January 9, 1994 to November 12, 1996, 1,536 model 432–04 (523 atrial) and 430–10 (1,013 ventricular) leads were implanted in 1,068 patients at 50 US and 5 Canadian centers to evaluate their safety and efficacy. The study included a general phase, with follow-ups at 1, 3, 6, 12, 18, and 24 months; and a randomized intensive phase with collection of more data and additional 2- and 6-week follow-ups. Capture and sensing thresholds, lead impedance, and handling characteristics were evaluated. Clinical events were monitored and performance was compared to that of two commercially available conventional (coaxial) leads: Sulzer Intermedics models 432–03 (atrial) and 430–07 (ventricular). During a total of 17,530 device months, there were two lead failures, no lead related deaths, 32 explants, 37 complications, and no unexpected adverse device effects. Capture thresholds were lower than those for coaxial controls with identical electrodes, sensing was comparable, lead impedances were within clinically acceptable ranges, and investigators found overall handling characteristics good to excellent. ThinLine coradial bipolar leads are safe and effective for cardiac pacing and sensing.