What is one consequence of a right to left shunt in cyanotic congenital heart defects?

In cyanotic congenital heart defects, a right-to-left shunt allows deoxygenated blood from the right side of the heart to flow directly into the left side, bypassing the lungs. This results in systemic circulation receiving blood that is lower in oxygen content, which leads to decreased oxygen saturation in the arterial blood. The body is then subjected to hypoxemia, which is the primary consequence of a right-to-left shunt.

This reduced oxygen saturation is a significant concern in cyanotic heart defects, as it can lead to a variety of symptoms, including cyanosis (bluish discoloration of the skin), difficulty breathing, and failure to thrive in infants and children. Enhanced systemic oxygen delivery typically relies on properly oxygenated blood being pumped from the lungs to the rest of the body, so the presence of a right-to-left shunt disrupts this process.

The other options do not accurately reflect the consequences of a right-to-left shunt: increased pulmonary circulation would occur in left-to-right shunts; reduced risk of brain abscesses and enhanced filtration of bacteria in the blood are not typically associated with the physiological changes resulting from a right-to-left shunt.