PACING REQUIREMENTS AFTER ORTHOTOPIC HEART-TRANSPLANTATION - INCIDENCE AND RELATED FACTORS

To assess the incidence of severe bradyarrhythmia and pacing requirements after orthotopic heart transplantation, as well as the possible causal mechanisms, we have reviewed our experience on 52 consecutive transplant patients. The overall incidence of bradyarrhythmia requiring pacing for at least 24 hours after transplantation was 27% (14 patients). The conditions of three of them required pacing for less than 1 week; the conditions of the other 11 patients (21%) required pacing for more than 1 week. Normal sinus rhythm resumed in all but four patients within 3 weeks; a permanent pacemaker was implanted in these four patients (7.6% of all 52 patients and 28% of patients requiring temporary pacing). Late complete heart block associated with acute rejection developed in two patients whose conditions required implantation of a permanent pacemaker. The age and sex of the recipient and donor were similar for patients with or without bradyarrhythmia. The percentage of patients with or without bradyarrhythmias taking amiodarone before transplantation (57% and 46%, respectively), total ischemic time (133 +/- 33 and 123 +/- 37 minutes, respectively), and cardiopulmonary bypass time (117 +/- 17 and 132 t. 65 minutes, respectively) were not significantly different for either group of patients. The initial temperature of cardioplegic solution for organ storage and the preimplantation myocardial temperature were, however, significantly lower in patients whose conditions required pacing immediately after transplantation than in those whose conditions did not require pacing (5.3 +/- 1.7-degrees-C versus 6.5 +/- 1.5-degrees-C, p < 0.05, and 3.9 +/- 1.6-degrees-C versus 5.7 2.6-degrees-C, p < 0.01, respectively). Initial endomyocardial biopsies revealed absent or mild rejection in the 14 patients with early bradyarrhythmia. A significant incidence of posttransplantation bradyarrhythmia occurs that requires temporary pacing, although normal sinus rhythm usually resumes within 2 to 3 weeks in most of the patients. A permanent pacemaker may be needed in about 11% of the patients. Low myocardial temperatures appear to be associated with early posttransplantation severe sinus or atrioventricular node dysfunction, which requires pacing.