Epidemiology and Etiology of Congenital Heart Diseases

Congenital heart disease (CHD), the most common type of birth defect, is an abnormal cardiocirculatory structure or function present at birth, although the disease is often discovered later in life. During prenatal life, the incidence of cardiac defect is higher due to affected fetuses that are aborted. CHD stems from an alteration in the embryonic development from a normal structure, or a failure of a structure to properly develop beyond an early stage of embryonic and fetal development. The non-typical patterns of cardio-circulatory flow owning to an anatomical defect may significantly influence the structural and functional development of the remainder of the circulatory system. Additionally, postnatal events have a marked impact on the clinical presentation of a specific isolated malformation. As CHD accounts for the most frequent cause of lethal malformation among infants, CHD is also considered a major problem affecting public health worldwide (Bernier et al., 2010). Despite the continuing progress in non-surgical and surgical treatments that allow for the survival of the majority of patients, some complex heart diseases are still associated with substantial morbidity and mortality. According to a report, 45% of infant deaths owing to congenital anomalies were caused by CHD in Western Europe. In Latin America, North America, Eastern Europe and the South Pacific region (including Japan) this proportion has been reported to be 35%, 37%, 42% and 48%, respectively (Botto, 2003). 20% of spontaneous abortions and 10% of stillbirths are attributed to CHD (Botto, 2001). CHD causes high morbidity and mortality among infants, and affects the quality of life during childhood and adulthood, depending on the progression of the disease (Majnener et al., 2008). It also affects social interactions and the quality of life for parents of children with CHD. While newborns with the cardiac disorder are symptomatic and identified soon after birth, many others are not diagnosed until the disease progresses into a severe stage. Data from the Northern Region Pediatric Cardiology database suggest around 1 in 4 cases of congenital heart disease in the UK are diagnosed later in childhood (Petersen et al., 2003). The signs and symptoms of heart disease depend on the type and severity of the disease. Children with critical cardiac lesion generally exhibit high morbidity and mortality because the risk of morbidity and mortality increases as treatment and diagnosis is delayed. The screening process is very important to detect congenital heart malformations. One of the major contributors to increased mortality and morbidity is clinical deterioration and heart