title: Unexpected loss of bipolar pacing with implanted dual chamber pacemakers.
abstract: Bipolar leads are most commonly used in the current practice of pacemaker therapy. In our study of 124 patients implanted with Guidant/Cardiac Pacemakers (CPI) Vigor dual chamber pacemakers, 5 patients had unexpectedly abrupt increases in bipolar lead impedance and pacing threshold 2 weeks to 18 months postimplantation without changes in sensing function. With the lead configuration reprogrammed to unipolar, the lead impedance and pacing threshold were restored to appropriate ranges. The changes in bipolar lead parameters can be caused by the CPI's "Quick Connect" (QC1) header lead system incorporated in these pacemakers.
authors.affiliation: Division of Cardiology, Chang Gung Memorial Hospital, Kaohsiung, Taipei, Taiwan, Republic of China.
authors.forename: G B
authors.initials: GB
authors.lastname: Guo
authors.forename: M C
authors.initials: MC
authors.lastname: Chen
authors.forename: C C
authors.initials: CC
authors.lastname: Wang
authors.forename: K C
authors.initials: KC
authors.lastname: Chang
authors.forename: M
authors.initials: M
authors.lastname: Fu
mesh_terms: D000368:Aged; D002304:Cardiac Pacing, Artificial; D004868:Equipment Failure; D005260:Female; D006327:Heart Block / Q000628:therapy*; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial; D012189:Retrospective Studies; D012804:Sick Sinus Syndrome / Q000628:therapy*