Affiliation:
1. From the Service of Cardiology, Valencia University Clinic Hospital (F.J.C., J.C., L.M., J.S., V.L.-M.), and the Departments of Electronics (J.G.) and Physiology (L.S.), Valencia University, Valencia, Spain.
Abstract
Background
—The purpose of this study was to determine whether the myocardial electrophysiological properties are useful for predicting changes in the ventricular fibrillatory pattern.
Methods and Results
—Thirty-two Langendorff-perfused rabbit hearts were used to record ventricular fibrillatory activity with an epicardial multiple electrode. Under control conditions and after flecainide, verapamil, or
d,l
-sotalol, the dominant frequency (FrD), type of activation maps, conduction velocity, functional refractory period, and wavelength (WL) of excitation were determined during ventricular fibrillation (VF). Flecainide (1.9±0.3 versus 2.4±0.6 cm,
P
<0.05) and sotalol (2.1±0.3 versus 2.5±0.5 cm,
P
<0.05) prolonged WL and diminished FrD during VF, whereas verapamil (2.0±0.2 versus 1.7±0.2 cm,
P
<0.001) shortened WL and increased FrD. Simple linear regression revealed an inverse relation between FrD and the functional refractory period (
r
=0.66,
P
<0.0001), a direct relation with respect to conduction velocity (
r
=0.33,
P
<0.01), and an inverse relation with respect to WL estimated during VF (
r
=0.49,
P
<0.0001). By stepwise multiple regression, the functional refractory periods were the only predictors of FrD. Flecainide and sotalol increased the circuit size of the reentrant activations, whereas verapamil decreased it. The 3 drugs significantly reduced the percentages of more complex activation maps during VF.
Conclusions
—The activation frequency is inversely related to WL during VF, although a closer relation is observed with the functional refractory period. Despite the diverging effects of verapamil versus flecainide and sotalol on the activation frequency, WL, and size of the reentrant circuits, all 3 drugs reduce activation pattern complexity during VF.
Publisher
Ovid Technologies (Wolters Kluwer Health)
Subject
Physiology (medical),Cardiology and Cardiovascular Medicine
Reference37 articles.
1. Allessie MA Wijffels MC Dorland R. Mechanisms of pharmacologic cardioversion of atrial fibrillation by class I drugs. J Cardiovasc Electrophysiol . 1998;9(suppl):S69–S77.
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