Renal Artery Stenosis

Definition

Renal artery stenosis a narrowing of one or both of the main arteries supplying the kidney. This causes a decrease in blood flow to 1 or both kidneys. The kidneys filter and remove waste from the blood.

The Kidney and its Main Blood Vessels

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Causes

Each kidney is capable of regulating the body’s blood pressure to assure that each organ has an adequate supply of oxygenated blood. Stenosis activates a cascade of hormones known as the renin-angiotensin system. This pattern increases blood pressure. High blood pressure is a leading cause of stroke and heart attack.

The 2 most common causes of renal artery stenosis are:

• Atherosclerosis—Fatty plaque builds up in the arteries and blocks blood flow to the kidneys. This occurs mainly in men over 50 years old.
• Fibromuscular dysplasia—An inherited disorder where muscle and fibrous tissue of the renal artery wall thicken and harden into rings that block blood flow to the kidneys. This occurs mainly in young women in their 30s.

Risk Factors

Factors that may increase your chance of renal artery stenosis include:

• Smoking
• High blood pressure
• Atherosclerosis elsewhere in your body
• Previous stroke or heart attack
• Diabetes
• Cholesterol or triglyceride disorders

Symptoms

Most people with renal artery stenosis have no symptoms. In those who have them, symptoms may include:

• Fluid retention
• Shortness of breath
• Headaches
• Ankle swelling

If both renal arteries are blocked, kidney failure occurs.

Diagnosis

You will be asked about your symptoms and medical history. A physical exam will be done. If you have elevated blood pressure, a search for its cause can involve many different tests. Unless there is a specific reason to suspect renal artery stenosis, it may not be considered at first.

Repeat blood pressure measurements may be done.

Your bodily fluids may be tested. This can be done with:

• Blood tests
• Urine tests

Imaging tests may be done to evaluate the kidneys. These may be done with:

• X-rays with contrasting dye
• Renal ultrasound
• Radioisotope imaging
• CT or MRI scans with or without injected contrast agents

Your heart's electrical activity may be measured. This can be done with an electrocardiogram (EKG).

Treatment

Talk with your doctor about the best treatment plan for you. If there is significant stenosis and you are healthy, repairing the renal artery may be considered before medical treatment. Treatment options include:

Medication

Standard treatment for high blood pressure may be enough if blood pressure can be controlled and the kidneys are functioning well enough. There are many medications that lower blood pressure. You may need several to achieve adequate control. These medications are effective in people who have one blocked renal artery. ACE inhibitors should not be used if hypertension is caused by renal artery stenosis of both kidneys.

Percutaneous Angioplasty

A thin tube is threaded into the renal artery from a puncture in your groin. The tube includes a balloon, laser, or other device that will open the narrowed artery.

Vascular Surgery

If angioplasty cannot be done on the artery, a surgeon may decide to repair the condition through an incision in your abdomen.

Nephrectomy

Nephrectomy is an option if the affected kidney has been so damaged that it no longer works, but still causes high blood pressure. Nephrectomy is a procedure to remove part or all of the kidney.

Prevention

Renal artery stenosis is an unusual cause of hypertension, but an important one because it is curable. The best way to detect hypertension is to have routine blood pressure measurements.

You can also prevent atherosclerosis by exercising regularly, eating a heart healthy diet, quitting smoking, and drinking less alcohol.