Rate-responsive pacing using the atrio-ventricular conduction time: design and test of a new algorithm

Area of Science:

• Biomedical Engineering
• Cardiovascular Physiology
• Medical Device Technology

Background:

• Chronotropic incompetence limits heart rate adaptation to physical exertion.
• Pacemakers are a common therapy, but rate-responsive pacing needs improvement.
• Existing pacemakers may not adequately address the complex cardio-circulatory system's response to strain.

Purpose of the Study:

• To develop and evaluate a new pacemaker algorithm using atrioventricular conduction time (AVCT) as a sensor parameter.
• To enhance heart rate responsiveness in patients with chronotropic incompetence.
• To address limitations of current rate-responsive pacing systems.

Main Methods:

• Developed a novel pacemaker concept utilizing atrioventricular conduction time (AVCT) as a sensor.
• Conducted identification experiments to analyze AVCT behavior under varying exercise and pacing frequencies.
• Implemented a rate-responsive algorithm based on internal model control, accounting for system's closed-loop nature and respiratory influences.
• Tested the AVCT-based algorithm in seven patients during incremental exercise.

Main Results:

• The AVCT-based algorithm demonstrated effective attenuation of respiratory-related disturbances.
• Pacemaker-paced heart rates significantly increased compared to intrinsic rates during exercise (126 +/- 12 min⁻¹ vs. 100 +/- 20 min⁻¹).
• The algorithm showed potential to restore chronotropic competence, with significant heart rate increases (26 +/- 13 min⁻¹).

Conclusions:

• The novel AVCT-based pacemaker algorithm is suitable for restoring chronotropic competence.
• The algorithm effectively extends the range of individual heart rate and stabilizes pacing.
• This approach offers a promising advancement in rate-responsive cardiac pacing.