Congenital Heart Defects

Congenital Heart Defects, also referred to as CHDs, are problems with the structure of the heart since birth. “Congenital” means “since birth” – meaning that CHDs are not acquired later in life. Some common CHDs are a hole in the heart, leaky valves or malformed heart chambers, but there are a whole range of them. All of them affect the function of the heart, in different ways.


In the majority of cases, the cause of CHD is unknown. Some risk factors have been identified, such as getting a Rubella infection while pregnant or consuming certain medications during pregnancy. At least 15% of CHDs are associated with genetic conditions, with the most common being Down Syndrome. Yet, the cause of CHD is still largely unknown.


There are many different types of CHD. They can occur alone (‘isolated’), or more than one defect can occur together, such as Tetralogy of Fallot, which is a combination of four different defects. The most common type of CHD is a ventricular septal defect (VSD), where there is a hole in the wall separating the lower two chambers of the heart.

Critical CHD

Some CHDs are classified as a ‘critical CHD’. These refer to a group of defects that require surgical intervention before the first year of life. Every 1 in 4 babies with a CHD will be born with a ‘critical CHD’.