In a Doppler exam for suspected renovascular hypertension, which parameter best indicates renal artery stenosis?

The Renal/Aortic Ratio (RAR) is a vital parameter in assessing renal artery stenosis, particularly in the context of a Doppler exam for suspected renovascular hypertension. It compares the peak systolic velocity of blood flow in the renal artery to that of the aorta. This ratio serves as an effective marker because the renal artery, when stenosed, typically exhibits a significantly higher peak systolic velocity compared to the aorta. A high RAR indicates a greater likelihood of significant stenosis in the renal artery, thus helping in diagnosing renovascular hypertension.

In clinical practice, using the RAR is preferred for its sensitivity and specificity in distinguishing between normal and abnormal findings related to renal artery blood flow. The threshold for concern is typically defined, where a higher RAR indicates more severe stenosis, making it a crucial measurement for practitioners evaluating patients for potential renovascular hypertension.

While peak systolic velocity, end-diastolic velocity, and resistance index are indeed valuable parameters in assessing vascular conditions, they do not provide the same clear diagnostic threshold for renal artery stenosis as the RAR does, making it the most reliable indicator in this specific situation.