REPETITIVE VENTRICULAR RESPONSES INDUCED BY RADIOFREQUENCY ABLATION FOR IDIOPATHIC VENTRICULAR-TACHYCARDIA ORIGINATING FROM THE OUTFLOW TRACT OF THE RIGHT VENTRICLE

In 23 consecutive patients, radiofrequency (RF) ablation was used as t reatment for idiopathic ventricular tachycardia (VT) originating from the outflow tract of the right ventricle. In this study, rye focused o n the repetitive ventricular response (> 5 consecutive QRS beats durin g RF application). The incidence and clinical implications of the repe titive ventricular response were examined through the results of endoc ardial mapping and RF ablation. VT origin was mapped as the earliest a ctivation site during VT, and it was determined within 0.5 X 0.5 cm (n arrow site) in 13 patients and wider than 0.5 x 0.5 cm (wide origin) i n the other 10 patients. The repetitive ventricular response was induc ed during application of RF current in 14 of 23 patients (61%), and it was more frequently observed in VT from a wide origin (100%) than in the VT from a narrow site (31%). The QRS morphology of the repetitive ventricular response was identical to that of clinical VT. As RF appli cation was continued and/or repeated, the RR interval of the repetitiv e ventricular response was gradually prolonged, the number of consecut ive QRS complexes was decreased, and clinical VT was finally eliminate d. The overall success rate of RF ablation was 96% (22/23 patients), a nd no complications were observed. In conclusion, a repetitive ventric ular response was frequently/observed in idiopathic right VT. The chan ging pattern of repetitive ventricular response, slowing, and/or disap pearing was consistent with successful RF ablation.