What is tricuspid atresia?

Tricuspid atresia (TA) is a congenital (present at birth) heart defect that occurs due to abnormal development of the fetal heart during the first eight weeks of pregnancy. The tricuspid valve, normally located between the right atrium and the right ventricle, does not develop properly during pregnancy.

Normally, oxygen-poor (blue) blood returns to the right atrium from the body, travels to the right ventricle, then is pumped through the pulmonary artery into the lungs where it receives oxygen. Oxygen-rich (red) blood returns to the left atrium from the lungs, passes into the left ventricle, and then is pumped through the aorta out to the body.

In tricuspid atresia, however, the following occurs:

  • Improper development of the tricuspid valve. The tricuspid valve does not form at all, and instead a plate of tissue is present in its place. This plate of tissue prevents oxygen-poor (blue) blood from passing from the right atrium to the right ventricle and on to the lungs as it should.
  • The right ventricle may be underdeveloped.
  • Openings may be present in the atrial and ventricular walls (atrial and ventricular septal defects), allowing oxygen-poor (blue) blood and oxygen-rich (red) blood to mix with each other.

A patent ductus arteriosus also allows blood to pass through from the aorta to the pulmonary artery and receive oxygen from the lungs. Tricuspid atresia makes up 1 to 2 percent of all cases of congenital heart disease. TA occurs equally in boys and girls.