Multiple pulse generator malfunctions with a dual chamber pacemaker.

The aim of this study was to evaluate the dual chamber uni/bipolarpacemaker Minidual 50, manufactured by Sorin Biomedica. Between 1995 and 1998, 66 Minidual 50 models were implanted at the Heart Institute. During the follow-up period of 33 +/- 12.8 months (range 0-50 months), total function loss in seven (10.6%) units and false threshold measurement of sensing and pacing in three (4.5%) patients were observed. Average time from implantation to malfunction was 37 months (range 28-42). Malfunction was unrelated to battery status and could not be predicted by any measures obtained during the pacemaker follow-up period. Kaplan Meyer survival curve predicted a 70% 4-year malfunction-free survival of that pacemaker model. Given this high rate of total malfunction and the unpredictable nature of its occurrence, the authors recommend the replacement of all remaining Minidual 50 units at risk, at least in dependent patients.