Prospective evaluation of pacemaker rate response in pediatric patients

Background: Patients with chronotropic incompetence can benefit from permanent pacemakers (PPM) with rate responsive (RR) pacing. This feature employs an accelerometer and allows for heart rate (HR) adaptation based on sensed patient activity. Due to congenital heart disease (CHD) and other constraints, pediatric patients may have an epicardial pacing system with a generator implanted in the abdomen. No studies have investigated if the site of generator implantation impacts the functionality of RR pacing. Objectives: The aim of this prospective study was to evaluate the difference in RR functionality of accelerometer-based pacemakers between patients with a generator placed in the abdomen versus thoracic location. Methods: Pediatric patients with a pacemaker implanted for complete heart block or sinus node dysfunction were enrolled. The pacemakers were temporarily reprogrammed to standardized RR parameters including activity thresholds, activity setpoints, and a HR range of 60–175 beats per minute. The participants then completed a standard Bruce protocol treadmill stress. HRs were measured at 30 second intervals. Results: Ten pediatric patients with PPMs – five with abdominal and five with thoracic placement – were enrolled. No significant differences were found between the groups in age or exercise duration. There were no differences in the primary or secondary outcomes between the groups including HR change during exercise, maximum HR achieved, and time to maximum HR. Conclusion: PPM generator location does not seem to result in differences in RR functionality. These findings support individualized PPM programming and highlight the need for further pediatric-focused device research.