Background: The Ventricular Capture Management (VCM) of Medtronic Kappa 700 series pacemakers (PM) performs automatic threshold detection and optimization of pacing output that may enhance generator longevity. We evaluated efficacy and safety of this algorithm in children.
Methods: The study was prospective, non-randomized, involving 50 consecutive patients (mean age 5.6 +/- 6.6 years, median 4 years), enrolled at first PM implant. VCM was active from the implant, with nominal values of safety margin, minimum adapted pulse amplitude and width. Leads were endocardial and epicardial, all unipolar. Thresholds and pacing outputs were registered with telemetric PM interrogation. Endocardial and epicardial thresholds and outputs were also compared. Follow-up duration was 27 +/- 13 months (range 6-49 months).
Results: A significant reduction in pulse amplitude was evident since the sixth month. Thresholds and outputs were lower in endocardial than in epicardial pacing. A false negative capture detection occurred during the "acute phase" in 3 patients (6.0%), with incorrect automatic output increase to 5 V/1 ms. After this phase, the problem was still detected in 2 patients (4.0%). VCM correctly identified threshold increases in 2 patients (1%). No pacing defect was documented. VCM was not performed in 4 infants (8.0%) for pacing rate > or = 100 b/min.
Conclusions: VCM function is safe and effective in reducing pacing output in pediatric patients; this may increase PM longevity. Epicardial pacing shows higher thresholds and outputs than endocardial pacing.