• Renal Artery Stenosis

    Definition

    Renal artery stenosis occurs when a kidney (renal) artery narrows. This causes a decrease in blood flow to that kidney. The kidneys are a pair of bean-shaped organs. They filter and remove waste from the blood. Stenosis is narrowing that restricts an opening.
    The Kidney and Its Main Blood Vessels
    IMAGE
    Copyright © Nucleus Medical Media, Inc.
    Each kidney regulates the body’s blood pressure to make sure that each organ has enough oxygenated blood. This happens by activating the renin-angiotensin hormone system.
    Renal artery stenosis triggers the release of these hormones. This release causes hypertension (high blood pressure). Since hypertension is a leading cause of strokes and heart attacks , this is a serious condition that requires diagnosis and treatment.
    Renal artery stenosis can eventually lead to loss of renal function. However, since one kidney can perform adequately by itself, both kidneys would have to be affected for kidney failure to occur. Both renal arteries are involved 30% of the time.

    Causes

    There are several diseases of arteries that can cause them to become narrowed, including:

    Risk Factors

    Factors that increase your risk of developing renal artery stenosis include:
    • Sex: male
    • Age: over 50
    • Atherosclerosis elsewhere in your body
    • Previous stroke or heart attack
    • Smoking
    • Hypertension
    • Diabetes

    Symptoms

    The main symptom of renal artery stenosis is high blood pressure. Only 1-5% of cases of high blood pressure are caused by renal artery stenosis. This should be suspected if you:
    • Develop high blood pressure when you are younger than 35 or older than 55
    • Have sudden worsening of previously well-controlled hypertension
    • Require multiple medicines to control blood pressure
    • Develop abnormalities in kidney blood tests after you take a certain type of blood pressure medication (ACE inhibitors)
    High blood pressure is called the “silent killer” because it rarely produces symptoms until a stroke or heart attack occurs. The best way to detect it is to have routine blood pressure measurements. Renal artery stenosis is an unusual cause of hypertension, but an important one because it is curable.
    Most patients with renal artery stenosis have no symptoms. However, it may also cause:
    • Fluid retention
    • Shortness of breath
    • Headaches
    • Ankle swelling
    If both renal arteries are blocked, kidney failure occurs. Kidney failure can cause:
    • Drowsiness
    • Decreased mental function
    • Twitching
    • Cramps
    • Convulsions
    • Nausea
    • Vomiting
    • Unpleasant tastes in the mouth
    • Malnutrition
    These symptoms are not specific to kidney failure. They may be caused by other health conditions that are either more or less serious. If you experience any of these symptoms, see your doctor.

    Diagnosis

    Your doctor will ask 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.
    Tests may include:
    • Repeat blood pressure measurements
    • Blood tests
    • Urine tests, which may include a 24-hour urine collection
    • Electrocardiogram
    • Specific tests of your kidneys including:
      • X-rays with contrasting dye
      • X-rays with contrast injected directly into the renal arteries
      • Ultrasound
      • Radioisotope imaging
      • CT or MRI scans with or without injected contrast agents

    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 hypertension may be enough if blood pressure can be controlled and the kidneys are functioning well enough. There are many medicines that lower blood pressure. You may need several to achieve adequate control. These medicines are very effective in people who have a 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.

    Prevention

    There is no way to prevent renal artery stenosis other than to prevent atherosclerosis. You can do so by exercising regularly, eating a heart healthy diet, quitting smoking, and drinking less alcohol.

    RESOURCES

    National Kidney Foundation http://www.kidney.org/

    National Institute of Diabetes and Digestive and Kidney Diseases http://www2.niddk.nih.gov/

    CANADIAN RESOURCES

    Heart and Stroke Foundation of Canada http://www.heartandstroke.com/

    The Kidney Foundation of Canada http://www.kidney.ca/

    References

    Balk E, Raman G, Chung M, et al. Effectiveness of management strategies for renal artery stenosis: a systematic review. Ann Intern Med . 2006;145:901-912.

    Krumme B, Donauer J. Atherosclerotic renal artery stenosis and reconstruction. Kidney Int . 2006;70:1543-1547.

    Renal artery stenosis. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed . Updated August 8, 2012. Accessed October 18, 2012.

    Zeller T. Renal artery stenosis: epidemiology, clinical manifestation, and percutaneous endovascular therapy. J Interv Cardiol . 2005;18:497-506.

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