To address the question of DDD generator longevity in the pediatric population, the data of the Registry was reviewed according to this protocol. All DDD generators implanted between 1/86 and 7/96 for which follow-up data existed and for which the pacing mode, i.e. epicardial or endocardial, were included. As will be seen later the predominate polarity for epicardial pacing was unipolar while for endocardial pacing it was bipolar. To enable appropriate comparisons to be made generators deviating from this were excluded - I.e. epicardial bipolar and endocardial unipolar generators were excluded.

Patient age at implant was 1 day to 27 years.

Generator failure was defined as battery depletion or electronic failure. Generators removed from use before end-of-service or due to patient death were classed as lost to follow-up.

Life table analysis was used to assess generator longevity