Heart rate and blood pressure variability in patients implanted with rate-responsive pacemaker

Area of Science:

• Biomedical Engineering
• Cardiology
• Physiology

Background:

• Rate-responsive pacemakers (PMs) aim to mimic physiological heart rhythms.
• The INOS(2+)-CLS pacemaker utilizes a closed-loop strategy (CLS) based on intracardiac impedance for rate adaptation.
• Autonomic nervous system control influences cardiac contractility, which is indirectly measured by impedance.

Purpose of the Study:

• To evaluate 24-hour beat-to-beat heart rate and blood pressure profiles in patients with CLS rate-adaptive pacemakers.
• To assess the efficacy of impedance-based rate adaptation in maintaining physiological variability.

Main Methods:

• Utilized a digital Holter system (Portapres) for 24-hour ECG and arterial pressure waveform acquisition.
• Developed an algorithm to classify pacemaker pacing modalities (DDD-R vs. DDD).
• Estimated beat-to-beat heart rate (HR), systolic pressure (SP), and diastolic pressure (DP).

Main Results:

• Studied 6 patients (4 with and without rate-responsive modes, 2 with rate-responsive mode only).
• Demonstrated that the rate-adaptive PM accurately preserves heart rate and blood pressure variability over 24 hours.
• Confirmed that impedance-based rate adaptation successfully maintains spontaneous HR, SP, and DP on a beat-to-beat basis.

Conclusions:

• The INOS(2+)-CLS pacemaker with closed-loop strategy effectively preserves physiological heart rate and blood pressure variability.
• Impedance-based rate adaptation is a viable method for enhancing pacemaker function.
• This technology supports more natural cardiovascular responses in pacemaker patients.