Which type of congenital heart defect may require an atrial septal defect to remain open for survival?

Hypoplastic left heart syndrome (HLHS) is a serious congenital heart defect characterized by underdevelopment of the left side of the heart. In this condition, the left ventricle, aorta, and other structures are significantly smaller or poorly formed, leading to inadequate blood flow to the body.

For infants with HLHS, the right side of the heart must compensate for the function of the left side. In most cases, for effective circulation, an atrial septal defect (ASD) is crucial. The ASD allows for blood from the right atrium to flow into the left atrium, facilitating oxygen-rich blood mixing and ensuring that some blood goes to the systemic circulation, which can help maintain viability until surgical interventions can be performed.

This reliance on the ASD is a critical aspect of managing HLHS, as without it, survival becomes nearly impossible due to insufficient blood flow to the body. Surgical management typically involves a series of procedures designed to reconfigure the heart's anatomy to improve function and circulation. Thus, the necessity of having the atrial septal defect remain open for survival makes HLHS the correct choice in this scenario.