Evaluation of pacemaker pulse generator and patient longevity in patients aged 1 day to 20 years

Abstract

The longevity of pediatric patients requiring pacemakers and the survival rates of the Implanted generators were evaluated. From January 1970 to December 1985, 96 patients aged 1 day to 20 years underwent 162 pulse generator implantation procedures. Indication for initial implantation was surgically induced heart block in 52 patients, sick sinus syndrome in 20, congenital complete heart block with symptoms of low cardiac output in 19 and tachydysrhythmia control in 5. Modal age at initial implantation was less than 1 year; median age was 5 years. During this period 90 generators were removed from service: 49 (54%) because of generator failure, 22 (24%) because the patient died, 12 (13%) because of elective upgrade at the time of lead failure or cardiac surgery, 5 (6%) because of generator pocket infection and 2 (2%) because of manufacturer's recall. Pulse generators were separated into 4 groups based upon generator technology. Group 1 (n = 16) were asynchronous units with mercury-zinc batteries; group II (n = 18) were single-chamber demand units with mercury-zinc batteries; group III (n = 14) were single-chamber demand units with rechargeable batteries; and group IV (n = 114) were single- or dual-chamber demand units with lithium batteries. Patient survival rate was 84% at 6 months and 70 % by 109 months. There was no further decrease to the end of the study period. Six-month generator survival rate was 82% for all groups, mostly a reflection of patient deaths. The next significant decrease in survival rates occurred at 14 months in group I, 19 months in group 11, 48 months in group III and 26 months in group IV. Fifty percent of generators were out of service by 17 months in group 1, 22 months In group 11, 52 months in group III and 63 months in group IV. By 108 months the group IV survival rate was only 28%. Despite improved battery and electronic technology, generator longevity in children is significantly less than the generator theoretical life expectancy and patient longevity. Patient survival rates indicate an excellent prognosis for children requiring pacemaker implantation, who would benefit from increased pulse generator longevity.