Apr 4, 2000

A mechanism of transition from ventricular fibrillation to tachycardia : effect of calcium channel blockade on the dynamics of rotating waves

Circulation Research
F H SamieJosé Jalife

Abstract

Abbreviation of the action potential duration and/or effective refractory period (ERP) is thought to decrease the cycle length of reentrant arrhythmias. Verapamil, however, paradoxically converts ventricular fibrillation (VF) to ventricular tachycardia (VT), despite reducing the ERP. This mechanism remains unclear. We hypothesize that the size and the dynamics of the core of rotating waves, in addition to the ERP, influence the arrhythmia manifestation (ie, VF or VT). The objectives of this study were (1) to demonstrate functional reentry as a mechanism of VF and VT in the isolated Langendorff-perfused rabbit heart in the absence of an electromechanical uncoupler and (2) to elucidate the mechanism of verapamil-induced conversion of VF to VT. We used high-resolution video imaging with a fluorescent dye, ECG, frequency and 2-dimensional phase analysis, and computer simulations. Activation patterns in 10 hearts were studied during control, verapamil perfusion (2x10(-6) mol/L), and washout. The dominant frequency of VF decreased from 16.2+/-0.7 to 13.5+/-0.6 Hz at 20 minutes of verapamil perfusion (P<0.007). Concomitantly, phase analysis revealed that wavefront fragmentation was reduced, as demonstrated by a 3-fold reduction in the...Continue Reading

  • References18
  • Citations48

Mentioned in this Paper

In Silico
Ventricular Fibrillation
Abnormal Fragmented Structure
Action Potentials
Photonics
Refractory Period, Electrophysiological
Calcium Channel
Nerve Conduction Function
Fluorescent stain
Chinchilla Rabbits

Related Feeds

Atrial Fibrillation

Atrial fibrillation is a common arrhythmia that is associated with substantial morbidity and mortality, particularly due to stroke and thromboembolism. Here is the latest research.

Antiarrhythmic Agents: Mechanisms of Action

Understanding the mechanism of action of antiarrhythmic agents is essential in developing new medications as treatment of cardiac arrhythmias is currently limited by the reduced availability of safe and effective drugs. Discover the latest research on Antiarrhythmic Agents: Mechanism of Action here.

Arrhythmia

Arrhythmias are abnormalities in heart rhythms, which can be either too fast or too slow. They can result from abnormalities of the initiation of an impulse or impulse conduction or a combination of both. Here is the latest research on arrhythmias.

Cardiac Conduction System

The cardiac conduction system is a specialized tract of myocardial cells responsible for maintaining normal cardiac rhythm. Discover the latest research on the cardiac conduction system here.