Congenital heart disease (CHD) is the most common develop mental anomaly and is found in about 1% of all live-born children. Recent progress in cardiac surgery and pediatric cardiology has resulted in large numbers of adult patients who have undergone surgical correction of complex congenital heart defects. It is esti mated that about 85% of newborns with heart defects will reach adulthood. The 32nd Bethesda Conference October 2000 guide lines indicate that the frequency of CHD in adults is about 2800 per million subjects, and in at least half of these, the disease is moderate or complex [1,2]. In 1996, the number of adult patients in Canada with congenital heart disease was 94 000, increasing to 124 000 in 2006. In the USA, it is estimated that each year the number of adults with congenital heart disease will increase by about 9000 cases, reaching 90 000 cases within 10 years. Among adults with congenital heart disease, the number of patients not undergoing any intervention (cardiological or cardiac surgery) is decreasing, owing to the growing population of subjects sub mitted for interventional cardiology procedures or one- or multi stage cardiac surgery.