In a patient with coarctation of the aorta, what discrepancy might be observed in the blood pressure?

In coarctation of the aorta, the narrowing of the aorta typically occurs just distal to the left subclavian artery, which can lead to a significant discrepancy in blood pressures between the upper and lower extremities. Specifically, this condition causes higher blood pressure readings in the upper body, including the arms and head, while the blood pressure in the lower extremities, such as the legs, tends to be lower.

This occurs because the coarctation restricts blood flow to the descending aorta, which supplies blood to the lower body. As a result, the lower extremities receive less blood flow and, consequently, display lower blood pressure compared to the upper extremities. Detecting this difference is a key clinical sign in the diagnosis of coarctation of the aorta and is typically evaluated in a physical exam during blood pressure measurement at different sites. Recognizing this finding aids in understanding the hemodynamics and potential complications associated with this congenital heart defect.