andardiovascular system occur in 7–10 per 1000 live births (0.7–1%). 113 It is the commonest form of congenital disease and accounts for approximately 30% of the total burden of congenital disease. With a decline in the incidence of rheumatic heart disease, congenital heart disease has become the main cause of heart disease in children in the developed world; 10–15% of affected children have associated congenital anomalies of the skeletal, genitourinary or gastrointestinal systems. Approximately 10–15% of patients with congenital heart disease may survive untreated to adulthood but the majority require some form of cardiac surgery as children. Nine lesions comprise more than 80% of congenital heart disease while a wide range of more unusual and complex lesions comprise the remainder.