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Abstract

Introduction: Bipolar temporary epicardial pacing leads have been designed to have better conduction characteristics than unipolar leads. In adults undergoing surgery for coronary artery disease, bipolar ventricular leads have been reported to be superior to unipolar leads. This study has been undertaken to compare the characteristics of unipolar and bipolar temporary epicardial pacing leads in the patients undergoing surgery for congenital heart disease, as no trials have been reported in this population. Hypothesis: We hypothesize that bipolar temporary epicardial pacing leads have superior pacing and sensing capabilities when compared with unipolar epicardial pacing leads. Methods: This is a prospective randomized unblinded controlled study of patients undergoing surgery for congenital heart disease in Cardiovascular Intensive Care Unit. Patients are randomized to receive either unipolar or bipolar temporary epicardial pacing ventricular leads at the time of surgery. The minimum current required to pace the heart (in milliamperes, mA), pacing threshold and minimum voltage sensed by the leads (in millivolt, mV), sensing threshold is studied until the day of removal of leads or for a maximum duration of 7 post-operative days (POD). The median (interquartile range) thresholds were obtained. Results: Interim analysis of data from 18 patients showed a trend of lower median pacing thresholds of bipolar leads 0.8 mA (0.5-1.75) on POD 1 and 1.5 mA (1.25-3.25) on POD 2 as compared with unipolar leads 1.5 mA (1-2 mA) on POD 1 and 2.5 mA (1.75-5.25) on POD 2. In addition, the median sensing thresholds were superior for bipolar leads 14 mV (6-20) on POD 1 and 12 mV (6-16) on POD 2 as compared with unipolar leads 10 mV (10-18) on POD 1 and 10.5 mV (6.5-16) on POD 2. There were no sensing or pacing failures of bipolar and unipolar leads in the ventricular position. Conclusions: The bipolar pacing leads are clinically reliable in the ventricular position in patients undergoing surgery for congenital heart disease and likely have superior sensing and lower pacing thresholds when compared to unipolar leads. Additional data with patients having the leads for longer duration is necessary to assess the thresholds beyond the second POD.