Activity-based pacing: comparison of a device using an accelerometer versus a piezoelectric crystal

Area of Science:

• Cardiology
• Biomedical Engineering
• Exercise Physiology

Background:

• Pacemaker rate-responsive technology aims to mimic intrinsic heart rate during physical activity.
• Accelerometer-based (AC) and piezoelectric crystal (PZ) sensors represent different technological approaches to achieve rate responsiveness.

Purpose of the Study:

• To compare the rate response accuracy of an AC pacemaker (EXCEL VR) and a PZ pacemaker (Legend) under various exercise conditions.
• To evaluate the appropriateness of pacemaker output in relation to subjects' intrinsic heart rate during graded exercise, bicycle ergometry, and stair climbing.

Main Methods:

• Ten healthy subjects (55-72 years) underwent graded treadmill tests.
• An additional ten subjects (50-66 years) performed bicycle ergometry and stair climbing protocols.
• Pacemaker pulse rates and intrinsic heart rates were continuously monitored and compared.

Main Results:

• AC pacemakers demonstrated higher correlation (r=0.92) with intrinsic heart rate during treadmill tests compared to PZ pacemakers (r=0.82).
• AC pacemakers had a smaller mean difference from intrinsic heart rate (11 ppm) versus PZ pacemakers (24 ppm).
• PZ pacemakers exhibited significantly lower maximal pulse rates and lagged behind intrinsic heart rate during bicycle ergometry and stair climbing.

Conclusions:

• Accelerometer-based pacemakers provide a more appropriate and accurate rate response during exercise compared to piezoelectric crystal pacemakers.
• The findings suggest AC technology may be superior for maintaining adequate cardiac output during varying physical demands.