Concurrent Failure of Active and Redundant Ventricular Epicardial Electrodes in Children

Implanting an unused or redundant epicardial ventricular pacing electrode in children at the time of initial electrode placement for later use is a common practice. To investigate the ultimate utilization of this redundant electrode, the records of 38 children who had undergone implantation of 47 redundant epicardial electrodes between I974 and I987 were reviewed. As the primary electrode remains functional, 12 electrodes have not been invasively tested or used; I1 were in nine children lost to follow-up. The remaining 24 redundant electrodes implanted in 16 children, (ages 1 day to 18 years, median 5 years, at implantation) together with the utilized electrode were evaluated at the time ofpacing system revision. At implant, all electrodes had thresholds < 1.4 volts at a pulse duration of 0.5 msec. At follow-up 0.2 to 11.7 years (mean 3.7 years) aRer implant, an electrode was considered functional i f the threshold at 0.5 msec pulse duration was < 2.5 volts, and 14 of 24 redundant electrodes were nonfunctional. Of the ten functional redundant electrodes, the active electrode was functional in seven cases. In only three of 24 cases was the redundant electrode functional when the active electrode was nonfunctional. In all cases, when the active electrode exhibited exit block, the redundant electrode also exhibited exit block. Two of jive redundant electrodes paired with a fractured active electrode were fractured. Two other redundant electrodes were fractured when the active electrode was functional. The state of the redundant and the active electrode was the same in 80% of the cases, P < 0.03. Of the 36 redundant electrodes implanted for which followup data is availablc 33 had not been used by the end of the study period. ( J Interven Cardiol 1989:2: 1)