Patients The study group will include otherwise 200 lthy patients aged 4 to 18 years, with an ASA physical status I or II, who are scheduled for elective radiofrequency ablation or cryoablation to interrupt abnormal foci and/or accessory pathways at Schneider Children's Medical Center of Israel (SCMCI). Written informed consent will be obtained from the patients (from age 12), parent(s) or legal guardian of all participants. Duration of the study- 2 years.