Torsades de pointes in a patient with Kearns-Sayre syndrome: a fortunate finding.

Children with single chamber pacemakers, in adolescence and young adulthood, may be upgraded to dual chamber systems, but there are no published data about indications, timing, and complications. Upgrading was attempted in 18 patients with transvenous pacing leads. A retrospective analysis of all collected data was performed. At initial pacemaker implantation (mean +/- SD, 9.3 +/- 4.1 years), the pacing mode was VVIR (n = 13 patients) and AAI/AAIR (n = 5 patients). After 72 +/- 41 months of follow-up, at the age of 15.5 +/- 5.2 years, upgrade was undertaken because of the patient's age at elective generator replacement (n = 3 patients), ventricular dysfunction (n = 7), syncope/presyncope (n = 3) in patients with VVIR pacing, atrioventricular block (n = 2), and/or drug refractory supraventricular tachyarrhythmias (n = 4) in patients with atrial pacing. In comparison with single chamber pacemaker implantations, the average procedural time and the average fluoroscopy time were not significantly longer. All suitable preexisting leads were incorporated in the new pacing system. Leads were inserted via the ipsilateral subclavian vein in 16 patients. Venous occlusion was found in two patients: in the first the procedure was not performed; in the second, the contralateral vein was used and the old lead was abandoned. There were no procedural complications. During a follow-up of 14 +/- 11 months, ventricular dysfunction worsened in five of seven patients; other patients benefitted symptomatically. In conclusion, pacemaker upgrade is technically challenging but feasible and safe and may be beneficial for some patients.