Hypertension (high blood pressure) represents the most common reason for health care office visits in the United States. It is estimated that over 50 million Americans and over 1 billion people worldwide have hypertension. Recently, the seventh report of the Joint National Committee on the Prevention, Detection, Evaluation, and Treatment of Hypertension changed the definition of hypertension to <120/80 mmHg. This will increase the number of Americans who are candidates for aggressive risk factor intervention and drug treatment for newly diagnosed hypertension.

The vast majority of patients with high blood pressure have primary hypertension i.e. there is no underlying medical reason for hypertension. Approximately 10% of patients have secondary hypertension, which has an underlying reason that if treated, cure or lower the high blood pressure. The most common causes of secondary hypertension include chronic kidney disease and medications, for example: non-steroidal anti-inflammatory drugs (ibuprofen, etc.); sympathomimetics (decongestants, antihistamines); oral contraceptives, and anabolic steroids.

One important secondary cause of hypertension, which has been shown to respond well to treatment is renal artery stenosis (RAS). Stenosis means narrowing, or partial blockage of the blood vessel that carries blood to the kidney. RAS may occur in younger (commonly female) patients, due to abnormal development of the artery wall known as fibromuscular dysplasia.

The cause of renovascular hypertension in older patients is usually hardening of the arteries or atherosclerosis. Atherosclerosis is the most common cause of RAS. RAS is often found in patients with vascular disease in other areas (for example: coronary, carotid, abdominal aorta, and peripheral arteries).