Evaluation of the incidence and severity of late arrhythmias in patients with predisposing congenital heart defects--either due to the anatomy of the defect itself or as a result of a particular type of surgical intervention.In a retrospective long-term study authors analyzed 158 patients (divided into 5 groups) with congenital heart defects after surgical correction. Evaluated were: the incidence of rhythm disturbances, the type of arrhythmia and the need for medication or intervention.The most rhythm disturbances occurred in patients after physiological correction of D-transposition of the great arteries (68.5%) and these patients also mostly needed medication or pacemaker implantation; followed were by patients with hypoplastic left heart syndrome after Fontan procedure (40%), then were patients after long-term correction of tetralogy of Fallot (31.1%), atrial septal defect sinus venosus type with partial anomalous pulmonary venous return after Warden correction (25.7%) and congenitally corrected L-transposition of the great arteries (25 %). Most of these arrhythmias were asymptomatic and there was no need to treat them. There was an increased incidence of arrhythmias with time (p0.05).During childhood in patients after surgical correction late arrhythmias mostly do not represent a severe problem, but with time, when reaching adulthood, this may be an issue. It is therefore very important to understand the anatomy, physiology and the arrhythmogenic substrate of every high risk congenital heart defect (Tab. 2, Fig. 6, Ref. 10).