The malformation of tricuspid atresia consists of a complete agenesis of the tricuspid valve with an absence of a direct communication between the right atrium and right ventricle. Tricuspid atresia is the third most common form of cyanotic congenital heart disease. It is also the most common cause of cyanosis with left ventricular hypertrophy.
The natural history of this condition is such that, without surgical intervention, only one third of patients survive to age 1 year and only 10% live to age 10 years.
The Fontan procedure, which was first performed in 1968 and then described in 1971, has changed the natural history dramatically and allowed survival into the third and fourth decades of life.