Congenital heart disease is a term used to identify a group of conditions where the heart has not formed properly during foetal developement. Congenital means that the heart problem is present from birth even if it can only be detected later in childhood

CHDs are the most common birth defects. CHDs occur in almost 1% of births. Most forms of CHD are not severe and do not require treatment. Despite this, in 2011-12 over 10000 procedures were performed in the UK to treat babies and children born with CHD, with an overall survival of more than 95%. Thanks to these improvements in survival, the number of adults living with CHDs is increasing. It is now believed that the number of adults living with CHDs is at least equal to, if not greater than, the number of children living with CHDs.

Only about 25% of children born with CHD requires surgery to repair their heart. Advancement in the diagnosis and treatment have made in possible for over 85% of babies born with a CHD to live to at least 18 years of age. However, children born with more severe formsof CHDs are less likely to reach adulthood. People with CHDs who survived paediatric cardiac surgery are now living long enough to reach an age where they can develop illnesses that are typical of adult age, such as high blood pressure, overweight and obesity and acquired heart disease. CHDs now represent the most common heart problem observed in pregnant women.

Most causes of CHDs are unknown. It appears that only about 15% of all CHDs are related to known genetic conditions (such as Down’s Syndrome or DiGeorge syndrome). Research suggests that most CHDs are likely caused by a combination of genes and other environmental risk factors, such as medications, vitamin deficiencies and maternal medical conditions (like diabetes). Maternal obesity, smoking, and some infections also may raise the risk of having a baby with a CHD. Because the heart is formed so early in pregnancy, some of the damage might have already occurred by the time most women know they are pregnant. Importantly, CHD is higher in families where parents are consanguineous (related to each other). A baby’s risk of having a CHD is increased by 3 to 4 times if the mother, father, or a sibling already has CHD.

Congenital heart defects do not always lead to the development of symptoms.​ Indeed, a child can look completely well but still present an underlying cardiac defect, generally of mild significance. In these children, only a detailed examination might raise the suspicion of a heart problem. Symptoms also tend to vary by age. For example, failure to thrive, poor weight gain, feed intolerance, labored or fast breathing and blueness around the lips (called cyanosis or reduced blood oxygen content) are the most common symptoms in young children. Other symptoms like chest pain, palpitation, syncope (or blackout), poor weight gain, and reduced exercise tolerance or easy tiredness are more common in older children and adolescents.