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Influence of propranolol on the ventricular depolarization gradient
K Lasaridis1, V E Paul, D Katritsis
1Department of Cardiological Sciences, St. George's Hospital Medical School, London, United Kingdom.
Pacing and Clinical Electrophysiology : PACE
|May 1, 1991
Summary
Beta-blocker infusion increased pacemaker rate, suggesting non-adrenergic factors influence ventricular depolarization gradient (VDG) sensing for rate-responsive pacing. Exercise performance remained unaffected, highlighting complex VDG regulation.
Area of Science:
- Cardiology
- Biomedical Engineering
- Electrophysiology
Background:
- Ventricular depolarization gradient (VDG) sensing is a novel basis for closed-loop rate-responsive pacemakers.
- Previous research implicated sympathetic stimulation and catecholamines in VDG changes during exercise.
Purpose of the Study:
- To evaluate factors influencing VDG sensing in rate-responsive pacemakers.
- To assess the impact of propranolol on VDG-based pacemaker response during exercise and tilting.
Main Methods:
- Five patients with Prism pacemakers underwent exercise and tilting tests before and after propranolol infusion.
- The pacemaker's rate control parameter (RCP), a VDG numerical equivalent, was analyzed.
Main Results:
- Propranolol infusion increased pacing rate (mean 27 ± 12.9 bpm), indicating a direct drug effect on VDG.
- The RCP significantly differed post-propranolol (P < 0.01).
- Exercise performance and pacing rate response to exercise and tilting were not altered by beta-blockade.
Conclusions:
- Factors beyond adrenergic stimulation influence the ventricular evoked response and pacemaker rate adaptation.
- Non-adrenergic mechanisms play a role in VDG sensing for rate-responsive pacing.