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Cardiac output in single-lead VDD pacing versus rate-matched VVIR pacing
B Nowak1, T Voigtländer, E Himmrich
1II Medical Clinic, Johannes Gutenberg University, Mainz, Germany.
Insights
Atrioventricular synchronous pacing (VDD) significantly improves cardiac output and stroke volume compared to single-chamber rate-responsive pacing (VVIRm) during low-intensity exercise. This finding highlights the benefits of VDD pacing for daily activities.
Area of Science:
- Cardiology
- Biomedical Engineering
- Exercise Physiology
Background:
- The optimal pacemaker mode for low-intensity daily activities remains debated.
- Single-lead VDD pacing offers atrioventricular synchrony, while VVIR pacing adjusts rate based on activity.
- Understanding hemodynamic differences is crucial for patient management.
Purpose of the Study:
- To compare hemodynamics between single-lead VDD pacing and rate-matched VVIR pacing (VVIRm).
- To evaluate the impact of pacing modes on cardiac output during low-intensity exercise.
Main Methods:
- Eleven patients with normal left ventricular function and VDDR pacemakers were studied.
- Low-intensity treadmill tests were performed under VDD pacing and VVIRm pacing.
- Cardiac output was measured using carbon dioxide rebreathing; stroke volume and oxygen uptake were also assessed.
Main Results:
- VDD pacing yielded significantly higher cardiac output (10.6 vs 9.2 L/min; p < 0.002) compared to VVIRm.
- Stroke volume was significantly greater with VDD pacing (90.7 vs 71.6 ml; p < 0.001).
- Maximal oxygen uptake was also higher in VDD mode (1,183 vs 1,076 ml/min; p < 0.01).
Conclusions:
- Single-lead VDD pacing demonstrates superior hemodynamic performance over VVIRm during low-intensity exercise.
- Atrioventricular synchronous pacing enhances cardiac output and stroke volume, potentially improving daily functional capacity.
- These findings support the use of VDD pacing for patients engaging in regular daily activities.
Abstract:
The importance of atrioventricular synchronous pacing compared with single-chamber rate-responsive pacing is still under discussion, especially for low-intensity workload representing daily life activities. We evaluated hemodynamics in single-lead VDD pacing versus VVIR pacing in 11 patients (8 men and 3 women, aged 58.6 +/- 13.8 years) with normal left ventricular function and a previously implanted single-lead VDDR pacemaker. A low-intensity steady-state treadmill test at 1 to 2.5 mph with a gradient of 2% to 4% was performed. Cardiac output was determined using a standard carbon dioxide rebreathing technique. Initially, the VDD mode was programmed, and after 5 minutes of exercise, cardiac output was measured in steady-state conditions. The pacemaker was then reprogrammed to the VVI mode at a rate 5 to 10 beats above the maximal atrial tracking rate to simulate rate-matched VVIR pacing (VVIRm). After 5 additional minutes of steady-state exercise, cardiac output was measured again. The maximal atrial rate in the VDD mode was 119 +/- 19 beats/min versus a programmed rate of 129 +/- 18 beats/min in the VVIRm mode. VDD pacing resulted in a significantly higher cardiac output than VVIRm pacing (10.6 +/- 1.9 vs 9.2 +/- 1.4 L/min; p < 0.002), with a mean difference of 1.6 +/- 1.2 L/min between the 2 modes. In the VDD mode, stroke volume (90.7 +/- 20.1 vs 71.6 +/- 13.0 ml; p < 0.001) and maximal oxygen uptake (1,183 +/- 264 vs 1,076 +/- 289 ml/min, p < 0.01) were also higher than in VVIRm.(ABSTRACT TRUNCATED AT 250 WORDS)