Tricuspid Atresia

Uncommon; occurs in 0.056:1000 live births.

Hypoxia caused by limited pulm blood flow.

Reliable systemic and pulm blood flow in these pts depends on existence of an unobstructed atrial level right to left shunt, an unobstructed left to right ventricular septal defect, and intact pulm artery.

There is obligatory mixing of systemic venous blood return to the heart from the vena cavas (lower O ₂ sat) and blood return to the heart from the pulm veins (higher O ₂ sat).

Inadequate ability of systemic venous and pulm venous blood to mix caused by restrictive atrial septal defect (rare additional problem, but vital).

Inadequate pulm blood flow caused by restrictive ventricular septal defect, pulm artery stenosis, pulm subvalvular obstruction, or pulm atresia.

Less common is that the pt that presents with too much pulm blood flow and CHF (completely unobstructed pulm blood flow).

Defined by the lack of a connection between the right atrium and hypoplastic (could be practically nonexistent) right ventricle.

The tricuspid valve may be completely absent, or there may be a rudimentary valve-like structure on the floor of the right atrium that is not patent.

Basically, there are three major types:

• Tricuspid atresia with normally related pulm artery and aorta (70–80%). There are three subtypes:

  • Ia Tricuspid atresia with normally related great vessels, pulm atresia, and no ventricular septal defect (pulm blood flow completely dependent on the maintenance of a patent ductus arteriosus in the immediate period after birth)

  • Ib Tricuspid atresia with normally related great vessels, hypoplasia of the pulm artery, and a small ventricular septal defect

  • Ic Tricuspid atresia with normally related great vessels, no hypoplasia of the pulm artery, and a large ventricular septal defect

• Tricuspid atresia with transposition of the great arteries (pulm artery arising from the left ventricle and the aorta arising from the hypoplastic right ventricle—20–30%). There are three subtypes:

  • IIa tricuspid atresia with transposed great arteries, atresia of the pulm artery arising from the left ventricle, and a ventricular septal defect allowing systemic blood flow to occur through the aorta arising from the hypoplastic right ventricle (pulm blood flow completely dependent on the maintenance of a patent ductus arteriosus in the neonatal period)

  • IIb tricuspid atresia with transposed great arteries, hypoplasia of the pulm artery arising from the left ventricle and a ventricular septal defect

  • IIc tricuspid atresia with transposed great arteries, no hypoplasia of the pulm artery, and a ventricular septal defect

• Tricuspid atresia with congenitally corrected transposition of the great arteries. The pt can have varying degrees of pulm, subpulmonary, or subaortic stenosis. Also, can be assoc with other lesions like atrioventricular septal defect.