What is a clinical indicator of coarctation of the aorta?

A clinical indicator of coarctation of the aorta is that the blood pressure proximal to the coarctation is elevated. This occurs because the narrowing of the aorta creates a situation where the blood flow before the site of coarctation is under higher pressure, leading to an increase in blood pressure in the arteries that originate before this constriction. Typically, patients with aortic coarctation will demonstrate significantly higher blood pressures in the upper body, while blood pressure is lower in the lower extremities, which is diagnostic for the condition.

In contrast, the other options do not accurately reflect the clinical findings associated with coarctation of the aorta. Blood pressure equal in both arms would not be expected; usually, there is asymmetry due to the obstruction. The absence of a patent ductus arteriosus (PDA) is not necessarily indicative of coarctation, as many individuals with coarctation do not have a PDA. Increased heart rate alone is nonspecific and could be seen in various conditions, making it an unreliable indicator for diagnosing coarctation of the aorta.