Single-chamber cardiac pacing with two forms of respiration-controlled rate-responsive pacemaker

Area of Science:

• Cardiology
• Biomedical Engineering
• Exercise Physiology

Background:

• Ventilatory changes during exercise are linked to heart rate response.
• Thoracic impedance measurement is utilized in pacemakers for rate-adaptive pacing.
• Previous pacemaker technologies faced limitations such as myopotential interference.

Purpose of the Study:

• To evaluate the efficacy of Biorate (RDP3, MB-1) and Meta pacemakers in achieving appropriate chronotropic response during exercise.
• To assess the correlation between pacemaker rate and estimated oxygen consumption.
• To investigate the activity sensing capabilities and limitations of these pacemakers.

Main Methods:

• Symptom-limited treadmill exercise tests were conducted on 10 patients with Biorate and 11 patients with Meta pacemakers.
• Ventilatory and heart rate responses were monitored.
• Thoracic impedance was measured to assess pacemaker function and detect motion artifacts.

Main Results:

• Both Biorate and Meta pacemakers demonstrated significant rate response and improved exercise duration compared to fixed-rate pacing.
• Good correlations were observed between pacing rate and estimated oxygen consumption.
• Motion artifacts caused rate responses during arm movements, indicating potential for activity sensing, though also highlighting a limitation.

Conclusions:

• Biorate and Meta pacemakers provide effective rate-adaptive pacing during exercise, enhancing patient performance.
• The devices exhibit potential for activity sensing, but motion artifacts require consideration.
• While improved, earlier Biorate versions had issues like myopotential interference and lead erosion.