Electrophysiological Characteristics of Idiopathic Ventricular Tachycardia in Children

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Background: Idiopathic ventricular tachycardia (VT) has been reported to have a good prognosis, but there still might be the potential risk of sudden death. Methods and Results: The 46 consecutive children (mean age 11.7±3.4 years) with idiopathic VT were enrolled in this study. Monomorphic VT was detected in 39 patients and polymorphic VT in 7 patients. The VT originated from the right ventricle (RV) in 22 patients, and left ventricle (LV) in 17 patients. The VT was induced by exercise in 68% of the RVVT, 41% of the LVVT, and 100% of the polymorphic VT. The VT was induced by programmed ventricular stimulation in 41% of the RVVT, 35% of the LVVT, and none of the polymorphic VT. Adenosine tri-phosphate terminated the VT in 9 of 15 patients (60%). The mechanism of the VT was suspected to be triggered by activity in 36.4%, automaticity in 40.9%, and re-entry in 22.7% of the RVVT, whereas it was 52.9%, 5.9%, and 41.2% of the LVVT, respectively. Conclusions: The exercise inducibility was higher in polymorphic VT than the RVVT and LVVT, but no difference in the programmed stimulation. The sensitivity to adenosine tri-phosphate was not different between the RVVT and LVVT. In some patients with idiopathic VT, a non-verapamil sensitive re-entry was documented, which was more common in patients with ischemic heart disease or cardiomyopathy.