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Atrioventricular interval optimization and exercise tolerance
P Khairy1, M Talajic, M Dominguez
1Department of Medicine and the Research Center, Montreal Heart Institute, Quebec, Canada.
Pacing and Clinical Electrophysiology : PACE
|November 15, 2001
Summary
Rate-adaptive shortening of the atrioventricular (AV) interval in pacemakers improves exercise tolerance. However, optimizing the AV interval using Doppler echocardiography at rest did not further enhance exercise capacity.
Area of Science:
- Cardiology
- Biomedical Engineering
- Exercise Physiology
Background:
- Modern pacemakers offer advanced AV interval programming.
- Features include rate-dependent adjustments and pacing-specific intervals.
- Optimizing these settings may enhance patient exercise tolerance.
Purpose of the Study:
- To evaluate if optimizing pacemaker AV intervals improves exercise tolerance.
- To compare fixed vs. rate-adaptive AV intervals during exercise.
Main Methods:
- 14 patients with AV block and dual-chamber pacemakers participated.
- AV intervals were programmed as fixed, fixed with rate adaptation, or optimized with rate adaptation.
- Exercise tolerance was measured using spiroergometry and maximum oxygen uptake.
Main Results:
- Resting AV interval optimization improved cardiac index and mitral flow.
- Rate-adaptive AV interval shortening increased maximum oxygen uptake compared to fixed AV intervals.
- No significant difference was found between optimized and fixed rate-adaptive AV intervals.
Conclusions:
- Rate-adaptive AV interval shortening enhances exercise tolerance in pacemaker patients.
- Resting AV interval optimization using Doppler echocardiography did not provide additional exercise benefits.
- Pacemaker programming should consider rate-adaptive AV interval strategies.
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