Incidence and timing of activity parameter changes in activity responsive pacing systems.

Area of Science:

• Cardiology
• Biomedical Engineering
• Medical Device Technology

Background:

• Activity-responsive pacing systems aim to optimize heart rate based on physiological demand.
• Rate response parameter reprogramming is crucial for effective pacemaker function post-implantation.
• Two common systems, VVI,R (Activitrax) and DDD,R (Synchrony), were compared.

Purpose of the Study:

• To evaluate the incidence and timing of rate response parameter reprogramming in VVI,R and DDD,R pacemakers during the first year post-implantation.
• To compare reprogramming strategies based on symptoms versus objective sensor data.
• To assess the predictive value of initial programming for long-term rate response requirements.

Main Methods:

• A comparative study involving 24 patients with VVI,R systems and 21 patients with DDD,R systems.
• Activitrax patients' parameters were adjusted based on symptoms.
• Synchrony patients' parameters were adjusted using sensor data from slow and fast walk protocols.

Main Results:

• No significant difference in reprogramming incidence over the year for Activitrax patients.
• Synchrony patients showed a higher incidence of reprogramming at 1 month compared to later visits (P < 0.02).
• Early post-implant sensor data (4-6 weeks) revealed alterations in sensor response, potentially due to local changes at the pacemaker site.

Conclusions:

• Predischarge programming may not accurately reflect long-term rate response needs in activity-responsive pacing systems.
• Early evaluation of sensor function using an exercise protocol (4-6 weeks post-implant) is recommended for all pacemakers using piezoelectric crystals.
• Objective data and serial evaluation are valuable for optimizing pacemaker settings.