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Haemodynamic advantage with single chamber rate responsive pacemakers over dual chamber pacemakers during exercise in
A K Maity1, S P Ghosh, A Dasbiswas
1Department of Cardiology, Institute of Post Graduate Medical Education & Research, Calcutta.
Insights
Patients with pacemakers benefit from VVIR mode during exercise. This mode, which adjusts heart rate (chronotropic response), significantly improved exercise duration and performance compared to VVI or DDD modes in patients with complete heart block and chronotropic incompetence.
Area of Science:
- Cardiology
- Biomedical Engineering
- Exercise Physiology
Background:
- Cardiac pacing modes (VVI, VVIR, DDD) influence cardiac performance.
- Sequential chamber activation and heart rate responsiveness (chronotropic response) are key determinants of cardiac function during exercise.
- Patients with complete heart block and sinus node dysfunction often require pacemakers.
Purpose of the Study:
- To compare the effectiveness of VVIR pacing mode against DDD and VVI modes.
- To assess the impact of sequential chamber activation and chronotropic response on cardiac performance during exercise.
- To determine optimal pacing strategies for patients with chronotropic incompetence and complete heart block.
Main Methods:
- A comparative study involving ten patients (mean age 68 years) with complete heart block and sinus node dysfunction.
- Patients underwent graded treadmill tests (Bruce protocol) in VVI mode, followed by either DDD or VVIR mode.
- Measurements included exercise duration, maximum rate-pressure product, exercise capacity, and cardiac output.
Main Results:
- VVIR mode demonstrated a significant increase in exercise duration (P < 0.001) and maximum rate-pressure product (P < 0.001) compared to DDD and VVI modes.
- DDD mode showed a statistically significant improvement over VVI mode (P < 0.005), but less pronounced than VVIR.
- Patients with VVIR pacing exhibited superior exercise performance.
Conclusions:
- VVIR pacing mode is superior to VVI and DDD modes for patients with chronotropic incompetence and complete heart block during dynamic exercise.
- The ability to modulate heart rate (chronotropic response) is crucial for optimizing cardiac performance in these patients.
- Pacemaker mode selection significantly impacts functional capacity in patients with complex conduction abnormalities.
Abstract:
Sequential cardiac chamber activation and chronotropic response are amongst the important determinants of cardiac performance. This study compared VVIR mode with DDD and VVI mode to assess the contribution of these two factors in the determination of cardiac performance during exercise. Ten patients with a mean age of 68 +/- 5 years were studied during 1988-90, who had complete heart block and sinus node dysfunction with a mean LV ejection fraction of 51.5 +/- 6.25%. Five patients had DDD pacemakers and the rest had VVIR pacemakers. Patients were exercised first in VVI mode followed by either DDD or VVIR mode. Exercise duration, maximum rate pressure product, exercise capacity and cardiac output were measured with graded treadmill test in Bruce protocol. There was remarkable increase in the exercise duration (P < 0.001) and the maximum rate pressure product (P < 0.001) in patients with VVIR as compared to DDD and VVI mode. In DDD mode, as compared to VVI mode, this increase was less remarkable, though statistically significant (P < 0.005). Therefore, it is concluded that patients with chronotropic incompetence as well as complete heart block do better during dynamic exercise when they have VVIR mode compared to VVI or DDD mode.