VDDR PACING IN CHILDREN AND YOUNG-ADULTS

The Pacesetter AddVent single-pass VDDR pacemaker with AV Plus pacing lead system was evaluated in 213 patients during Phase I and II invest igation from 33 U.S. and 2 Canadian participating study centers. The a im of this study was to compare the sensing and pacing parameters in a younger patient subset with an older adult population. There were 9 p atients under age 35, and 204 patients over age 35 years (mean 75 year s), with the majority between 60-90 years. Males accounted for 59% of patients and females comprised 41% of patients. Criteria for enrollmen t required a minimum weight of 35 kg. All patients had normal sinus fu nction at implant, with either 2nd or 3rd degree atrioventricular (A-V ) block. The implant indications in the younger group were congenital heart block or post-operative heart block following repair of congenit al heart disease. Investigation of implant and follow-up characteristi cs revealed no significant differences in atrial or ventricular sensin g, ventricular capture thresholds, or lead impedance during the first year post-implantation. In conclusion, a single-pass VDDR pacing syste m can be utilized in children weighing over 35 kg and young adults wit h certain forms of repaired congenital heart disease. Sensing and capt ure thresholds were determined to be as reliable in this unique subset of pacemaker patients, and were not different from adults implanted w ith the same VDDR pacing system. An important exclusion is sinus node dysfunction, which may occur late following congenital heart surgery. Longer follow-up will be necessary to address the issues of growth and loss of atrial floating electrode sensing in developing children.