The Zenicor-EKG method is in use in more than 20 pediatric cardiac clinics in Scandinavia. The advantage with Zenicor-EKG is its easy-to-use. No fixed chest electrodes are necessary. The patient can very easyly bring the Zenicor-EKG during the school day or during sports activities. The patient uses the Zenicor-EKG at home as a long time as required to catch the arrhythmia, up to several months! The probability to detect and diagnose the arrhythmia increases with the prolonged investigation time.