Renal Artery Disease

What is renal artery disease?

What causes renal artery disease?

Why does my doctor think that I might have renal artery disease?

What tests are used to diagnose renal artery disease?

What treatment is available for renal artery disease

 What is renal artery disease?

Renal artery disease may be defined as a narrowing of the blood supply to the kidneys. When the kidneys have a normal blood supply, they filter toxins from the blood and help to keep blood pressure in the normal range. Some patients with renal artery disease have no symptoms or mild symptoms, while in others it leads to severe high blood pressure (hypertension), poor kidney function or even kidney failure and dialysis.
Other terms used to describe renal artery disease include:

-renovascular disease
-renovascular hypertension
-ischemic nephropathy
-renal artery stenosis

 What causes renal artery disease?

Atherosclerosis (hardening of the arteries) is the most common cause of renal artery disease. It is caused by a combination of factors including cigarette smoking, elevated cholesterol, high blood pressure and diabetes. Atherosclerosis may also cause heart attacks and strokes. The second leading cause of renal artery disease is fibromuscular dysplasia, a disease of the artery wall. The cause of fibromuscular dysplasia is unknown. There are also other unusual causes of renal artery disease.

 Why does my doctor think that I might have renal artery disease?

It is important to remember that only about 3% of patients with high blood pressure have renal artery disease. However, because high blood pressure is improved or even cured after treatment of renal artery disease, it is important for your doctor to consider this diagnosis. Some findings that might cause your doctor to suspect that you have renal artery disease include:

-high blood pressure that requires 3 or more drugs to control
-"uncontrolled" high blood pressure (continued high blood pressure despite attempts to treat with medication)
-high blood pressure causing a stroke or fluid on the lungs (pulmonary edema)
-high blood pressure developing in a patient younger than 20 years or older than 55 years
-worsening kidney function in a patient with other signs of atherosclerosis (such as previous stroke or heart attack) -worsening kidney function after taking particular types of high blood pressure medications called angiotensin-converting enzyme (ACE) inhibitors (captopril, enalapril, lisinopril, etc.)
-bruit (abnormal sound) heard when listening to the abdomen with a stethoscope

 What tests are used to diagnose renal artery disease?

The dye study (also called angiogram, arteriogram, or aortogram) is the best test to diagnose renal artery disease. During this test, a radiologist injects dye into the arteries of the abdomen to search for a narrowing of the kidney arteries. A dye study requires a needle-stick in an artery (usually in the groin) and may require an overnight stay in the hospital. They may also cause temporary or permanent damage to the kidneys, or other complications.

Because of these possible complications, many patients suspected of having renal artery disease have a screening test first. A number of screening tests exist for renal artery disease. Our preference for a screening test is for kidney ultrasound (renal duplex sonography), which uses an ultrasound probe placed over the skin to get images of the renal arteries. Because the kidney ultrasound does not require an intravenous line (IV), dye, or medications, it is considered a "non-invasive" test. It usually takes less than an hour to complete and is risk-free for the patient. Not all hospitals use this test because it requires a highly skilled ultrasound technician. Another popular screening test for renal artery disease is the captopril renogram. Before undergoing this low-risk X-ray study, the patient receives a dose of captopril by mouth. For many patients, this test gives very useful information. Unfortunately, the results of this test are less accurate when patients have poor kidney function or narrowing of the arteries to both kidneys. Other screening tests are also used. Magnetic resonance angiography (MRA) is low-risk for the patient but requires the patient to spend a long period in a cramped space and many patients with claustrophobia may find the MRA to be an unpleasant experience. Spiral computed tomography (CT scan) is also used to diagnose renal artery disease. This test requires dye injected through a vein (IV) but does not require a puncture of a groin artery. Regardless of the type of screening test used, an angiogram is usually required to determine the best treatment for renal artery disease.

What treatment is available for renal artery disease?

Three different treatments are available for patients with renal artery disease:

-medical therapy
-surgery
-angioplasty (balloon treatment)

Not all patients with renal artery disease require surgery or angioplasty. Because both procedures have associated risks, only patients with symptoms from renal artery disease should undergo intervention. Patients with renal artery disease and mild or moderate symptoms should have medical therapy. This includes medication to control high blood pressure and regular physical examinations (including blood pressure measurement and blood tests of kidney function). This way, worsening symptoms can be treated if they occur. Generally, patients with renal artery disease require a procedure when they have severe high blood pressure or kidney failure.

As mentioned before, two procedures are available to treat renal artery disease: surgery and angioplasty. Surgery requires an incision to open the abdomen and a hospital stay of a week or longer. After surgery, the kidney arteries usually remain open for the rest of the patient's life. High blood pressure is cured or improved in most patients, and kidney failure is improved in two-thirds of patients, even patients on dialysis before the operation. Angioplasty uses a plastic balloon inserted through a groin artery to break open the narrowed portion of the artery. Often, a metal stent is also inserted after angioplasty to prop open the artery. Angioplasty does not require an incision or long hospital stay. Angioplasty is an excellent treatment for renal artery disease from fibromuscular dysplasia. Results from angioplasty for atherosclerosis are not as good. Unfortunately, renal artery disease may recur (come back) after angioplasty. Patients with renal artery disease causing severe symptoms usually require some form of procedure. Because both surgery and angioplasty have advantages and disadvantages, the correct choice of therapy is depends on the patient and the cause of renal artery disease. However, because renal artery disease may cause high blood pressure, kidney failure or even dialysis, it is important that patients have a clear understanding of the options available.