It is ironic that the first transistorized, wearable pacemaker was designed by Earl Bakken specifically to make open heart surgery in children possible (1). Despite their pediatric origins, however, current heart rhythm control devices and leads are not designed or manufactured for children. Instead, they are designed with adults in mind, with respect to device size and lead length, as well as to the indications that prompt pacemaker implantation in adults. For this reason, the clinician who implants pacemakers in children and who follows such children must adapt the technology to the unique requirements of children. These requirements include the need for small size, but they also include flexibility in programmability, to take into account potentially higher levels of activity, higher natural heart rates, and the wide spectrum of problems encountered with congenital heart disease.