INTRACORONARY ETHANOL ABLATION IN SWINE - EFFECTS OF ETHANOL CONCENTRATION ON LESION FORMATION AND RESPONSE TO PROGRAMMED VENTRICULAR STIMULATION

Introduction: Intracoronary ethanol ablation has been successfully use d as arrhythmia therapy, but the dose response of ventricular function and arrhythmogenesis to varying ethanol concentrations is undefined. Methods and Results: Twenty-six anesthetized pigs weighing 50+/-11 kg underwent left and right heart catheterization. Ablation solutions com posed of normal saline with ethanol in concentrations of 0%, 10%, 25%, 50%, 75%, and 100% were mixed with metrizamide, a nonionic contrast a gent (3.75 g per 20 mL), then infused into branch or distal coronary a rteries in each of the left anterior descending and left circumflex co ronary artery distributions. Hemodynamic measurements, and coronary an d left ventricular angiography were performed before and after ablatio n. Programmed electrical stimulation was performed preablation and at a chronic study at 4 to 6 days. Excised hearts were examined pathologi cally. Fifty-two lesions were created in 26 animals, and 24 animals su rvived to the follow-up study. Minimal hemodynamic alterations were ob served in response to ablation. As the ethanol concentration of the ab lation solution was increased, the prevalence of spontaneous nonsustai ned and sustained ventricular tachyarrhythmias increased (P=0.0002), t he ablation vessels were more persistently occluded (P=0.028), and the postablation global left ventricular ejection fraction showed greater impairment (P=0.002). Identifiable myocardial lesions were identified in all study groups, including those receiving the 0% ethanol infusio n. Lesion size increased significantly with increasing ethanol concent ration (P=0.0004) but there was significant variance within groups. In response to programmed electrical stimulation, ventricular fibrillati on was a nonspecific finding before and after ablation. In contrast, m onomorphic ventricular tachycardia was induced only at postablation te sting, and four of five of these animals underwent infusions with etha nol concentration of greater than or equal to 50% ethanol. Conclusion: Concentrations of greater than or equal to 50% ethanol are most effec tive in creating large ventricular lesions in intracoronary ethanol ab lation, but are associated with more impairment of left ventricular fu nction, and have a greater likelihood of acute and early chronic arrhy thmia aggravation.