Why do newborns with tricuspid valve atresia require an ASD and VSD for survival?

Newborns with tricuspid valve atresia require a patent atrial septal defect (ASD) and a ventricular septal defect (VSD) for survival primarily to facilitate communication between heart chambers. In tricuspid valve atresia, the tricuspid valve is either absent or malformed, preventing normal blood flow from the right atrium to the right ventricle.

The presence of an ASD allows oxygenated blood from the left atrium to flow into the right atrium and then into the right ventricle, enabling some degree of mixing of oxygenated and deoxygenated blood. However, without a tricuspid valve, blood cannot effectively enter the right ventricle to be pumped to the lungs for oxygenation, leading to reliance on the ASD for pulmonary blood flow.

Meanwhile, a VSD allows blood to flow between the left and right ventricles, providing another route for mixing and enabling oxygen-rich blood to reach the systemic circulation. These shunts are essential because they help maintain a sufficient level of oxygenation in the bloodstream and support circulation despite the heart's structural abnormalities.

Together, the ASD and VSD create pathways for blood to move through the heart and the lungs, which is critical for the survival