Renal artery stenosis (or a narrowing of the   kidney artery) is most commonly caused by atherosclerosis or hardening of the arteries, although there are other causes such a fibro-muscular dysplasia. If the narrowing is severe enough, it can limit the flow of blood to the kidneys. When the kidneys do not receive adequate blood flow, they attempt to compensate by elevating blood pressure.  While not the most common cause of high blood pressure, if left untreated it often progresses to renal insufficiency (renal failure). Therefore, if your physician has a suspicion that you may have renovascular hypertension, a duplex ultrasound may be ordered to determine if you have any narrowing. Duplex ultrasound, a relatively inexpensive, noninvasive technique, is particularly suited to detect a narrowing as it obtains pictures of the vessels and information about the blood flow in real time. No other technique provides both the anatomic and physiologic information which is of prime importance in this condition.

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