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Effect of adrenergic stimulation on action potential duration restitution in humans
Peter Taggart1, Peter Sutton, Zaid Chalabi
1The Hatter Institute, Department of Cardiology, University College London HospitalsLondon, WC1E 6DB. peter.taggart@uclh.org.
Circulation
|January 23, 2003
Summary
Adrenergic agonists like isoprenaline and adrenaline steepen the action potential duration (APD) restitution slope in humans. This finding may explain how sympathetic activity promotes ventricular fibrillation.
Area of Science:
- Cardiovascular Physiology
- Electrophysiology
Background:
- Sympathetic activity influences ventricular arrhythmias.
- Action potential duration (APD) restitution is key to myocardial electrical stability.
- Steeper APD restitution slopes can trigger wave break and ventricular fibrillation.
Purpose of the Study:
- To investigate the effect of adrenergic stimulation on APD restitution in humans.
- To determine if adrenergic agonists alter the slope of APD restitution.
Main Methods:
- Monophasic action potentials recorded from the right ventricular septum in 18 patients.
- APD restitution curves constructed at 600, 500, and 400 ms cycle lengths.
- Infusion of isoprenaline or adrenaline during measurements.
Main Results:
- Adrenergic agonists (isoprenaline, adrenaline) significantly increased the steepness of the maximum slope of APD restitution.
- The effect was more pronounced at shorter basic cycle lengths.
- Control conditions showed steeper slopes at longer basic cycle lengths.
Conclusions:
- Isoprenaline and adrenaline enhance the steepness of the APD restitution slope in humans.
- This adrenergic effect on APD restitution may contribute to the facilitation of ventricular fibrillation.
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