What is characterized as the absence or abnormal development of the tricuspid valve in congenital heart disease?

Tricuspid atresia is a congenital heart defect characterized by the absence or abnormal development of the tricuspid valve, which is the valve that separates the right atrium from the right ventricle. In this condition, the right ventricle may be underdeveloped or non-functional because blood cannot flow properly from the right atrium to the right ventricle due to the lack of a functional tricuspid valve.

This condition often requires surgical intervention early in life to establish proper blood flow and improve the oxygenation of the blood. The other choices, while related to heart defects, refer to different abnormalities. Ebstein's anomaly involves a malformed tricuspid valve but does not present as complete atresia. Mitral regurgitation pertains to the mitral valve rather than the tricuspid valve, and aortic atresia refers to an obstruction in the aortic valve, not the tricuspid. Therefore, the defining characteristic of tricuspid atresia makes it the correct answer.