Renal (Kidney)

Renal Artery Stenosis

Definition:

Like any other major arteries, renal arteries which supply blood to the kidneys are also susceptible to blockages.

Renal artery stenosis is a narrowing of one or both of the main arteries supplying blood to the kidney. This causes a decrease in blood flow to one or both kidneys.

Symptoms:

Renal artery stenosis may cause no signs or symptoms until the condition reaches an advanced state. Most people with renal artery stenosis have no signs and symptoms. The condition is sometimes discovered incidentally during testing for some other reason. Your doctor may also suspect a problem if you have:

  • High blood pressure that begins suddenly or worsens without explanation.
  • High blood pressure that begins before the age of 30 or after the age of 50.

As renal artery stenosis progresses, other signs and symptoms may include:

  • High blood pressure that is difficult to treat.
  • A whooshing sound as blood flows through a narrowed vessel (bruit) which your doctor hears through a stethoscope placed over your kidneys.
  • Elevated protein levels in the urine or other signs of abnormal kidney function.
  • Worsening kidney function during treatment for high blood pressure.
  • Fluid overload and swelling in your body's tissues.
  • Treatment-resistant heart failure.

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 a stroke and heart attack.

The two 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 wherein 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:

Following people are at high risk of developing peripheral vascular disease and should get themselves evaluated by expert doctors:

  • Smoker
  • Diabetic
  • High blood pressure
  • High cholesterol
  • Heart patients
  • A family history of heart diseases, diabetes, hypertension
  • Kidney patients
  • Obese/overweight
  • Physically inactive
  • Age - Over 50 years

Examination:

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

Treatment:

Treatment options include:

  • Medical Management
    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 on 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 procedure consists of dilating the blood vessel with a balloon or dilating the beginning of the artery and subsequently placing the stent by using a special balloon that opens up the narrowed blood vessel to the kidney.
  • 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
    A 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 either a part or the entire kidney.
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