Modifications in ventricular fibrillation and capture capacity induced by a linear radiofrequency lesion
Francisco J Chorro1, Francisca Pelechano, Isabel Trapero
1Servicio de Cardiología, Hospital Clínico Universitario de Valencia, INCLIVA, Valencia, Spain. Francisco.J.Chorro@uv.es
Introduction And Objectives:
An analysis was made of the effects of a radiofrequency-induced linear lesion during ventricular fibrillation and the capacity to capture myocardium through high-frequency pacing.
Methods:
Using multiple epicardial electrodes, ventricular fibrillation was recorded in 22 isolated perfused rabbit hearts, analyzing the activation maps upon applying trains of stimuli at 3 different frequencies close to that of the arrhythmia: a) at baseline; b) after radio-frequency ablation to induce a lesion of the left ventricular free wall (length=10 [1] mm), and c) after lengthening the lesion (length=23 [2] mm).
Results:
Following lesion induction, the regularity of the recorded signals decreased and significant variations in the direction of the activation fronts were observed. On lengthening the lesion, there was a slight increase in the episodes with at least 3 consecutive captures when pacing at cycles 10% longer than the arrhythmia (baseline: 0.6 [0.7]; initial lesion: 1 [1], no significant differences; lengthened lesion: 3 [2.8]; P<.001), while a decrease was observed in those obtained upon pacing at cycles 10% shorter than the arrhythmia.
Conclusions:
The radio-frequency -induced lesion increases the heterogeneity of myocardial activation during ventricular fibrillation and modifies arrival of the activation fronts in the adjacent zones. High-frequency pacing during ventricular fibrillation produces occasional captures during at least 3 consecutive stimuli. The lengthened lesion in turn slightly increases capture capacity when using cycles slightly longer than the arrhythmia.
