Related Experiment Videos
Electrophysiologic effects of dextro- and levo-verapamil on sinus node and AV node function in humans
H Echizen1, M Manz, M Eichelbaum
1National Institute of Nutrition, Tokyo, Japan.
Journal of Cardiovascular Pharmacology
|January 1, 1988
Summary
Dextro (d)- and levo (l)-verapamil equally affect heart nodes, but the l-isomer is 20 times more potent. This study compared the electrophysiologic effects of verapamil isomers on cardiac conduction.
Area of Science:
- Cardiology
- Clinical Electrophysiology
Background:
- Verapamil is a calcium channel blocker used for supraventricular tachyarrhythmias.
- Understanding the differential effects of verapamil isomers is crucial for optimizing antiarrhythmic therapy.
Purpose of the Study:
- To compare the electrophysiologic effects of dextro (d)- and levo (l)-verapamil on sinoatrial (SA) and atrioventricular (AV) nodes.
- To determine the relative potency of d- and l-verapamil in modulating cardiac electrophysiology.
Main Methods:
- Electrophysiologic evaluation in ten patients with supraventricular tachyarrhythmias.
- Administration of d- and l-verapamil to assess effects on sinus node recovery time (SNRT) and AH interval.
- Measurement of plasma concentrations of both isomers.
Main Results:
- Both d- and l-verapamil significantly prolonged SNRT and AH interval.
- No qualitative difference in electrophysiologic effects between the isomers was observed.
- L-verapamil demonstrated approximately 20-fold greater potency than d-verapamil, with lower effective plasma concentrations.
Conclusions:
- Both verapamil isomers exhibit similar slow channel blocking effects on the SA and AV nodes in humans.
- L-verapamil is significantly more potent than d-verapamil, necessitating lower doses for equivalent electrophysiologic effects.