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Two-year experience with rate-modulated pacing controlled by mixed venous oxygen saturation
S Windecker1, R S Bubien, L Halperin
1Department of Medicine, University of Alabama at Birmingham 35294, USA.
Pacing and Clinical Electrophysiology : PACE
|July 22, 1998
Summary
Mixed venous oxy-hemoglobin saturation (MVO2) shows promise for rate adaptive pacing, but long-term sensor reliability is uncertain. While stable for the first year, MVO2 sensors deteriorated by 18-24 months in some patients.
Area of Science:
- Cardiology
- Biomedical Engineering
- Physiology
Background:
- Mixed venous oxy-hemoglobin saturation (MVO2) presents potential as a control parameter for rate adaptive pacing.
- Long-term in vivo reliability of MVO2 sensors for this application remains uncertain.
Purpose of the Study:
- To prospectively evaluate the long-term performance and reliability of a permanently implanted MVO2 saturation sensor for VVIR pacing.
Main Methods:
- Eight patients requiring VVIR pacing received implants with an integrated MVO2 sensor.
- Patients underwent serial submaximal and maximal treadmill exercise tests (Chronotropic Assessment Exercise Protocol) over 24 months.
- Pacing modes (VVI vs. VVIR) were compared using exercise testing and expired gas exchange measurements.
Main Results:
- VVIR pacing significantly increased peak exercise heart rate, oxygen consumption, and exercise duration compared to VVI pacing.
- MVO2 correlated well with oxygen consumption (VO2) and showed faster kinetics.
- The MVO2 sensor demonstrated stability and accuracy for the first 12 months, but signal deterioration occurred in 4/8 patients by 18-24 months.
Conclusions:
- Rate-modulated VVIR pacing controlled by MVO2 offers a chronotropic response highly correlated with VO2 and responds rapidly to workload changes.
- While MVO2 sensors are reliable for the first year, long-term signal deterioration necessitates further investigation for sustained clinical use.