The effect of chemical ablation of the endocardium on ventricular fibrillation threshold.

Abstract

The purpose of this study was to examine the effects of ablation of the superficial endocardium and Purkinje network on left ventricular fibrillation threshold. Lugol's solution was applied through small ventriculotomies to the left and right ventricular endocardium of 10 dogs on cardiopulmonary bypass. Two control groups of five animals each underwent either endocardial application of saline or epicardial application of Lugol's solution. perimentally to be an important substrate in ventricular tachycardia, its role in ventricular fibrillation is less clear.'2-' Nevertheless, transmural recordings during ventricular fibrillation have documented endocardial to epicardial spread of activation with variable block, implying an endocardial origin of many of the activation fronts that maintain the arrhythmia.'9The purpose of this study was to examine the effect of ablation of the superficial endocardium and Purkinje fiber network on the ability to initiate ventricular fibrillation. Lugol's solution, a concentrated iodine solution, has an affinity for glycogen. It has been demonstrated to stain and ablate both Purkinje fibers and endocardial tissue.2>22 In this study, the electrophysiologic effects of the endocardial application of Lugol's solution on ventricular fibrillation threshold were examined. In addition, the rheologic and histologic changes induced by this procedure were also investigated. MethodsTwenty adult mongrel dogs weighing 25 to 35 kg were anesthetized with intravenous sodium pentobarbitol (30 mg/kg) and maintained on a constant-drip infusion of 2 mg/min throughout the study.

Elimination of Purkinje Fibers by Electroporation Reduces Ventricular Fibrillation Vulnerability

“…In animal models targeting the Purkinje system, there has been a consistent demonstration of improved resilience toward VF11, 50 and polymorphic ventricular arrhythmias 51. On the basis of this reasoning, a window of vulnerability to VF was assessed via a shock‐on‐T‐wave phenomenon.…”

“…Biphasic shocks were delivered between the 2 coils, and the implantable cardioverter defibrillator generator was excluded from the shocking vector. The window of vulnerability was assessed by initially defining the lower limit and subsequently the upper limit of VF inducibility via a shock on T‐wave method 11, 21, 22. A 1‐J shock stimulus (S2) was delivered at 260 ms after a drive train of 8 ventricular paced stimuli.…”

“…However, current radiofrequency ablation approaches to the Purkinje fibers have limitations, particularly because they can only be applied in a point‐to‐point manner, which is tedious and time‐consuming. Chemical denudation of the Purkinje system has been attempted and shown to lower the VF threshold,11 but results in acute toxicity to the heart.…”

Vulnerability to ventricular fibrillation

“…The same premature stimuli did not induce VT or VF in the absence of ischemia. Thus, these results cannot be easily compared to studies in which the effects of chemical ablation on VF thresholds were studied, one of which reported an increase in VF threshold, 33 the other no effect. 34 It may be that the Purkinje system is only important for the transition to VF in the setting of acute ischemia.…”

The Role of the Purkinje System in Defibrillation

“…Thus, the PS aided in defibrillation. Experimentally, application of Lugol's solution to the endocardium results in a doubling of DFT (Damiano et al, 1986), suggesting that the PS facilitates defibrillation at lower field strengths.…”