Tricuspid Atresia

Overview

The normal pumping chambers of the heart (ventricles) must have an inflow valve to let blood in, a good-sized pumping chamber, and an outflow to allow blood to exit the chamber during contraction. In tricuspid atresia, the tricuspid valve, which lies between the heart’s upper right chamber (right atrium) and lower right chamber (right ventricle), doesn’t develop. As a result, it prevents oxygen-depleted blood that’s returning to the right atrium from the body from directly flowing into the right ventricle (the chamber that normally pumps blood to the lungs where it picks up oxygen). Instead, the venous blue blood must pass through a hole between the upper filling chambers (atria), where it then mixes with oxygen-rich blood returning from the lungs via the pulmonary veins. This combined blood then passes to the lower left pumping chamber.

Commonly in tricuspid atresia, the right ventricle may be small because blood flow to the right ventricle is blocked by the nonexistent tricuspid valve, and the right pumping chamber doesn’t receive a normal amount of blood. In many situations, there’s a hole between the two lower pumping chambers (ventricular septal defect [VSD]). Some of the blood ejected by the left ventricle passes out to the aorta on its way to the body, and some of the blood may cross the VSD to go to the lungs. Additionally, there may be muscular narrowing in the right ventricle under the pulmonary valve that keeps blood from entering the pulmonary arteries. In some situations, the main blood vessels exiting the heart (aorta and pulmonary arteries) may be connected to the wrong pumping chamber, which is called a transposition of the great arteries.

Progression and possible complications

How a child born with tricuspid atresia is affected after birth depends on how much blood flow is going to the lungs and if the flows to the lungs and body are balanced. It can be too little, too much, or just right.

• If there’s not enough blood going to the lungs from the heart to pick up oxygen, then the ductus arteriosus must be kept open—much like opening the back door if the front door is blocked—before a more definitive procedure is performed (i.e., could be a patent ductus arteriosus [PDA] stent). This is done using a medication called prostaglandin E1.
• If there’s too much blood going to the lungs, an operation such as a pulmonary artery banding procedure may need to be performed to limit the amount of blood that’s allowed to pass into the lungs. This will allow for a more balanced circulation and will protect the lungs from the high pressures of the left ventricle.
• If a baby is born with some natural narrowing, this may provide enough balance to prevent the need for an operation within the first few months of life.
• If D-transposition of the great arteries (D-TGA), a congenital heart defect where the aorta and pulmonary artery are switched from their normal positions, is present with tricuspid atresia, coarctation of the aorta (a narrowing in a part of the aorta) may also develop, which would require surgical repair.