Renal Artery Stenosis

Definition

Renal artery stenosis is a blockage or narrowing of the major arteries that supply blood to the kidneys.

Description

Renal artery stenosis occurs when the flow of blood from the arteries leading to the kidneys is constricted by tissue or artherosclerotic plaque. This narrowing of the arteries diminishes the blood supply to the kidneys, which can cause them to atrophy and may ultimately lead to kidney failure. It may also cause renovascular hypertension, or high blood pressure related to renal artery blockage.

Causes and symptoms

The two main causes of renal artery stenosis are atherosclerosis and fibromuscular disease. Fibromuscular diseases such as fibromuscular dysplasia cause growth of fibrous tissues on the arterial wall. Stenosis may also occur when scar tissue forms in the renal artery after trauma to the kidney.

Renal arterial stenosis has no overt symptoms. Eventually, untreated renal arterial stenosis causes secondary complications such as chronic kidney failure, which may be characterized by frequent urination, anemia, edema, headaches, hypertension, lower back pain, and other signs and symptoms.

Diagnosis

The high blood pressure that is sometimes associated with renal artery stenosis may be the first sign that it is present, particularly if the hypertension is not responding to standard treatment. Presence of a bruit, a swooshing sound from the artery that indicates an obstruction, may be heard through a stethoscope.

An arteriogram, an x-ray study of the arteries that uses a radiopaque substance, or dye, to make the arteries visible under x ray, may also be performed. This test is used with caution in patients with impaired kidney function, as the contrast medium may cause further kidney damage.

Treatment

Treatment for renal artery stenosis is either surgical, pharmaceutical, or with angioplasty or stenting. Angioplasty involves guiding a balloon catheter down into the renal artery and inflating the balloon to clear the blockage. A stent may be inserted into the artery to widen the opening. Some patients may be candidates for surgical revascularization, which involves restoring blood flow with an arterial bypass. Drugs known as angiotension-converting enzyme (ACE) inhibitors may be prescribed for some patients. The chosen treatment approach depends on the cause of the stenosis and factors such as the patient's kidney function and blood pressure control.

Alternative treatment

Renal artery stenosis is a serious and potentially life-threatening condition, and should always be treated by a healthcare professional familiar with the disorder.

Prognosis

Untreated renal artery stenosis can cause hypertension (high blood pressure) and may ultimately lead to chronic kidney failure (end-stage renal disease).

Prevention

Maintaining a heart healthy lifestyle can help to prevent cases of renal arterial stenosis attributable to artherosclerosis. Strategies for avoiding vascular disease include eating right, maintaining a desirable weight, quitting smoking, managing stress, and exercising regularly.

Resources

PERIODICALS

Bloch, M. J., and T. Pickering. "Renal Vascular Disease: Medical Management, Angioplasty, and Stenting." Seminars in Nephrology 20, no. 5 (September 2000): 474-88.

Fenves, A. Z., and C. V. Ram. "Fibromuscular Dysplasia of the Renal Arteries." Current Hypertension Reports 1, no. 6 (December 1999): 546-9.

ORGANIZATIONS

American Kidney Fund (AKF). Suite 1010, 6110 Executive Boulevard, Rockville, MD 20852. (800)638-8299. 〈http://www.arbon.com/kidney/〉.

National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Natcher Building, 6AS-13K, 45 Center Drive, Bethesda, MD 20892-6600. 〈http://www.niddk.nih.gov〉.

National Kidney Foundation. 30 East 33rd Street, New York, NY 10016. (800)622-9020. 〈http://www.kidney.org〉.

KEY TERMS

Artherosclerotic plaque— A deposit of fatty and calcium substances that accumulate in the lining of the artery wall, restricting blood flow.

Atrophy— Cell or tissue wasting or death.

Chronic kidney failure— End-stage renal disease (ESRD); chronic kidney failure is diagnosed as ESRD when kidney function falls to 5-10% of capacity.

Edema— Swelling which occurs when body tissues retain fluid.

Stent— An expandable "scaffold-like" device, usually constructed of a stainless steel material, that is inserted into an artery to expand the inside passage and improve blood flow.