Tricuspid Atresia

Updated: Jul 14, 2022
  • Author: Mary C Mancini, MD, PhD, MMM; Chief Editor: Richard A Lange, MD, MBA  more...
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Tricuspid atresia is the third most common form of cyanotic congenital heart disease, with a prevalence of 1.03 per 10,000 live births. [1] The deformity consists of a complete lack of formation of the tricuspid valve with absence of direct connection between the right atrium and right ventricle.



Three types of tricuspid atresia are described, depending on the associated relationship of the great vessels. In type I, the great arteries are related normally; in type II, the great arteries are d-transposed; and in type III, the great arteries are l-transposed. The types are further subclassified according to the presence or absence of ventricular septal defects and pulmonary valve pathology. [2, 3]

Other cardiovascular anomalies occur in 15-20% of patients with tricuspid atresia. Most of the associated anomalies relate to transposition of the great vessels. A persistent left superior vena cava anomaly is observed in 15% of patients.

With the absence of the tricuspid valve and no continuity between the right atrium and right ventricle, venous blood returning to the right atrium can exit only by an intra-atrial communication. Because of the obligatory right-to-left shunt at the level of the atria, saturation of the left atrial blood is diminished.

The intracardiac blood flow in tricuspid atresia further depends on the presence or absence of pulmonary arterial pathology. [4] In the absence of pulmonary atresia or pulmonary valve stenosis, the volume of blood to the lungs may be normal with normal oxygenation occurring, resulting in reduced cyanosis. In contrast, with accompanying pulmonary artery or valve stenosis, pulmonary blood flow is reduced, resulting in increased cyanosis.

Pulmonary obstruction occurs most often in patients with tricuspid atresia and normally related great arteries. Patients with d-transposed great arteries and tricuspid atresia generally have unobstructed pulmonary blood flow.

The left ventricle comprises most of the ventricular mass in tricuspid atresia. Because of volume overload (the left ventricle receives all the venous return) and persistent hypoxemia, decreased ventricular function may result in fibrosis, decreased ejection fraction, mitral annular dilatation, and mitral insufficiency.



The cause is unknown. Although specific genetic causes of the malformation remain to be determined in humans, the FOG2 gene may be involved in the process. Mice in which the FOG2 gene is knocked out are born with tricuspid atresia. The significance of this finding and its applicability in humans requires further investigation.



United States data

An estimated 404 babies are born with tricuspid atresia each year in the United States. [1]

Race-, sex-, and age-related demographics

No racial predilection is apparent.

Considering all forms of tricuspid atresia, no sexual predilection exists. Males present more frequently with transposed great vessels than females.

The anomaly is congenital and is evident at birth.



The 1-year survival rate after the Fontan operation is 85%; the 5-year survival rate is 78%. Because the procedure eliminates cyanosis, polycythemia and left ventricular volume overload are relieved; therefore, this population can be expected to live longer.


Depending on the degree of obstruction and associated anomalies, tricuspid atresia may be lethal at birth. Without repair, the patient rarely survives to adulthood.