CATHETER ABLATION OF VENTRICULAR-TACHYCARDIA WITH RADIOFREQUENCY CURRENTS, WITH SPECIAL REFERENCE TO THE TERMINATION AND MINOR MORPHOLOGIC CHANGE OF REINDUCED VENTRICULAR-TACHYCARDIA

During catheter ablation with radiofrequency (RF) currents, the incidence of the termination of reentrant ventricular tachycardia (VT) during application of RF energy and the morphologic change of the reinduced VT were analyzed. Twenty-five patients (20 men and 5 women, aged 44 +/- 17 years) were studied. After induction of monomorphic sustained VT, the ablation site was determined by endocardial activation mapping, identification of isolated mid-diastolic potential, and pacing during tachycardia. Thirty-six monomorphic VTs were induced in 25 patients and terminated with programmed stimulation. The cycle length was 323 +/- 55 ms and all VTs were entrained with rapid ventricular pacing. The target site was the earliest site of activation of VT in 26 VTs in 16 patients, and the area of slow conduction in 10 VTs in 9 patients. VT was terminated soon after the application of RF currents in 33 VTs in 22 patients at 6.0 +/- 3.1 seconds, and VT was induced immediately after the cessation of RF currents in 11 patients. Of these, 4 patients with idiopathic left ventricular VT had an alternation in the QRS configuration before catheter ablation and required repeat ablation of the other VT morphology. In the other 7 patients, such morphology was not observed before ablation, but was observed in VT induced when the original VT was terminated. Repeated attempts of catheter ablation 2 to 9 times at the remapped site was, however, successful in 7 of 8 VTs. In the remaining 3 patients, ablation was attempted within the area of slow conduction, but VT was not terminated during RF and only minor morphologic change was observed in 1 patient. With the inclusion of these 3 patients, catheter ablation was unsuccessful only during 4 VTs in 4 patients.