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Endocardial wave front organization during ventricular fibrillation in humans
Gregory P Walcott1, G Neal Kay, Vance J Plumb
1Division of Cardiovascular Diseases, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA. gpw@crml.uab.edu
Objectives:
This study was designed to characterize the organization of ventricular fibrillation (VF) on the endocardium of humans.
Background:
Most proposed mechanisms for the maintenance of VF postulate the propagation of a number of activation wave fronts that reenter to maintain the arrhythmia. We tested the hypothesis that, in patients undergoing internal cardioverter-defibrillator implantation, VF consists primarily of a few large wave fronts on the endocardium.
Methods:
Electrograms were recorded from a 36-electrode catheter in the left ventricle of 16 patients during VF. Activation times were chosen for a 2-s epoch for each fibrillation episode, and a two-dimensional Kolmogorov-Smirnov test was performed to determine if activation occurred randomly along the catheter over that time interval. The maximum cross-correlation was found for all possible pairs of electrodes on the catheter, and these values were plotted relative to the distance between the two electrodes. An exponential curve was then fit to the data, and a length constant was determined. Activation times were grouped into wave fronts along the catheter, and the lengths of the wave fronts were estimated.
Results:
The Kolmogorov-Smirnov test showed that activation was not random along the catheter in any of the patients studied. The correlation length determined was 9 +/- 2 cm. The number of wave fronts recorded by the catheter was 9.2 +/- 2.9 wave fronts/s. The length of the pathway of each wave front along the catheter was 6.5 +/- 4.5 cm.
Conclusions:
Ventricular fibrillation is well organized on the endocardial surface of humans, consisting primarily of a few large wave fronts on the order of 6 to 9 cm.