[An experimental study of catheter ablation using microwave energy via coaxial electrode catheter]

The purpose of this study was to examine the efficacy, arrhythmogenicity, and the size of ablated lesions of catheter ablation with microwave energy. Microwave energy generated by a device with a frequency of 2450 MHz, was delivered via a bipolar electrode coaxial catheter with an electrode ball tip. Microwave ablation was applied (50 watts for 15-150 sec.) on the left ventricular endocardium in 6 dogs. No ventricular arrhythmia occurred during ablation in any of the dogs when microwave catheter ablation was applied for less than 45 sec. However, when the duration of microwave catheter ablation was longer than 45-60 sec, ventricular premature contractions were observed in all 6 dogs. When ablation time was set for a longer time, the dogs developed nonsustained ventricular tachycardias. Nevertheless, ventricular arrhythmias after ablation did not occur in all dogs. Ventricular programmed stimulation after ablation did not induce ventricular tachycardia in any of the dogs. When ablation time lasted more than 120 sec, the coagulation layer was extended to the epicardium in all 6 dogs. The results of this study suggest that microwave ablation is feasible for the treatment of tachyarrhythmias from a deep focus of the ventricular myocardium.