A congenital heart defect is a defect in the structure of the heart and great blood vessels of the newborn.
Congenital heart defects can be broadly categorised into two groups, acyanotic heart defects ('pink' babies) and cyanotic heart defects ('blue' babies). The acyanotic defects may further be divided into obstructive heart defects and shunts.
Slightly less than 1% of all newborn infants have congenital heart disease. Eight defects are more common than all others and make up 80% of all congenital heart diseases, whereas the remaining 20% consist of many independently infrequent conditions or combinations of several defects. Ventricular septal defect (VSD) is generally considered to be the most common type of malformation, accounting for about 1 / 3 of all congenital heart defects.
The incidence is higher when a parent or a sibling has a heart defect (4-5%), in stillborns (3-4%), abortuses (10-25%), and premature infants (2%).
The cause of most congenital heart disease is unknown. In most cases, it is of a multifactorial origin and is a result of both genetic predisposition and environmental factors. Known genetic causes of heart disease includes chromosomal abnormalities such as trisomies 21, 13 , and 18, as well as a range of newly recognised genetic point mutations, point deletions and other genetic abnormalities as seen in syndromes such as CATCH 22 , familial ASD with heart block , Alagille syndrome, Noonan syndrome, and many more.
Known ante-natal environmental factors include maternal infections (Rubella), drugs (alcohol, hydantoin, lithium and thalidomide) and maternal illness (diabetes mellitus, phenylketonuria, and systemic lupus erythematosus).