Related Experiment Videos
Do we need a reflex tachycardia to stand up?
Jacques-Olivier Fortrat1, Catherine Lemarie, Elisabeth Bellard
1Laboratoire de Physiologie, Faculté de Médecine, Centre Hospitalo-Universitaire, Faculté de Médecine, 49045 Angers Cedex, France. jofortrat@chu-angers.fr
Pacing and Clinical Electrophysiology : PACE
|September 24, 2005
Summary
Sophisticated pacemakers aiming to increase heart rate during standing did not improve blood pressure or cardiac output. This rate-rise pacing may even worsen blood pressure drops in some patients.
Area of Science:
- Cardiology
- Biomedical Engineering
- Autonomic Nervous System
Background:
- Advanced pacemakers aim to integrate with cardiovascular autonomic control for dynamic responses.
- This approach could benefit patients with vasovagal responses by increasing pacing rate to counteract blood pressure drops upon standing.
Purpose of the Study:
- To investigate if a rate-rise pacing mode improves cardiovascular response to standing compared to fixed-rate pacing.
Main Methods:
- Five patients with pacemakers underwent two 5-minute tilt tests in random order: fixed pacing (DDD) and close loop stimulation (CLS) for rate-rise.
- Beat-by-beat measurements of heart rate, systolic blood pressure, and cardiac output were recorded.
Main Results:
- No significant differences in systolic blood pressure or cardiac output changes were observed between DDD and CLS modes.
- However, CLS mode resulted in significant tachycardia in 3 patients and a >20 mmHg blood pressure fall in 3 patients, versus one patient in DDD mode.
Conclusions:
- Upright rate-rise pacing does not enhance systolic blood pressure or cardiac output during standing.
- This pacing strategy may paradoxically worsen blood pressure regulation in some individuals, indicating tachycardia alone is insufficient to offset orthostatic hypotension.