Evaluation of an in-line bipolar polyurethane ventricular pacing lead.

A study was undertaken to evaluate the performance of the Medtronic 4012 polyurethane in-line bipolar pacing electrode. One hundred twenty six patients implanted with the 4012 lead were followed by our clinic with 116 of these leads implanted at our institution. Patients were followed a minimum of every 4 months. Testing included the performance of stimulation thresholds, sensing thresholds, and provocative maneuvers to evaluate for myopotential inhibition testing a minimum of every eight months. There were 12 documented lead failures of the total 126 patients. Further analysis was limited to the ten failures occurring in the 116 leads implanted at our center. All ten failed leads utilized the suture anchoring sleeve. Six of the leads were left cephalic implants, three were right cephalic, and one was right subclavian. Manifestations of failure included: seven oversensing abnormalities, three undersensing, four loss of ventricular capture, one premature end of service, four lead impedance decreases to < 250 omega and some presentations in combination. No leads were explanted for evaluation. The Kaplan-Meier product limit method was used to estimate the time to lead failure. The probability of not experiencing a lead failure within the first 4 years of implant is estimated to be 0.9103 (SE = 0.0338). Pacemaker dependent patients implanted with the 4012 lead should be given special consideration for prophylactic replacement.