Automatic pace-sense polarity switch as an indicator of early lead corrosion: the usefulness of impedance trend graphing.
A rate responsive dual chamber pacemaker system (Medtronic Inc.) was implanted without complications. At 6-week postimplantation a routine pacemaker check showed a spontaneous switch from programmed bipolar pace-sense to unipolar pace-sense on the atrial and ventricular leads. Pacing and sensing thresholds were not significantly changed from implantation. The atrial and ventricular lead impedances increased from 680 and 720 ohms at implantation to 1,290 and 2,400 ohms, respectively. The device was reprogrammed to bipolar pace-sense and the continuous lead telemetry trend option was programmed On. Evaluation of the system 1 month later revealed a decrease in atrial and ventricular lead impedances, 680 and 2,100 ohms, without a change in pace-sense polarity. One month later, the lead polarity had again switched from programmed bipolar to unipolar pace-sense. The lead trend data revealed stable atrial impedances with sporadic increases in the ventricular lead impedance to values > 3,000 ohms. The pacemaker lead system was invasively investigated and visible gross corrosion of the ventricular lead distal connector pin was discovered.
Howard University College of Medicine, Washington, DC, USA.
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D003343:Corrosion; D017097:Electric Impedance; D004567:Electrodes, Implanted; D004868:Equipment Failure; D006801:Humans; D008297:Male; D010138:Pacemaker, Artificial; D013997:Time Factors