Renal Artery Stenosis

1 What is Renal Artery Stenosis?

The narrowing of one or more arteries that supply blood to your kidneys (renal arteries) is called Renal Artery Stenosis. Since the primary function of the arteries is to supply blood to the organs, once the renal arteries narrow it will prevent normal amounts of oxygen-rich blood from reaching your kidneys.

Adequate blood supply to the kidneys is needed to facilitate kidney functions such as filtration of waste products and removal of excess fluids. Therefore, reduced blood flow to the kidneys may increase blood pressure in your whole body (systemic blood pressure) due to water retention and injure the kidney tissue which will further cause complications.

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2 Symptoms

Most people with renal artery stenosis have no signs and symptoms until the condition reaches an advanced state. Often times, since renal artery stenosis is asymptomatic it is discovered whenever a person is being examined for another medical condition.

There are some other factors that may cause your doctor to suspect renal artery stenosis, this include:

  • High blood pressure that begins before age 30 or after age 55 as renal artery stenosis progresses.
  • High blood pressure that begins suddenly.

Other signs and symptoms include:

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

It is important that you are aware of the signs and symptoms of renal artery stenosis so that you would know what to watch out for and if you are already observing presence of these symptoms that is starting to worry you then it best to seek medical advice as soon as possible.

3 Causes

The two main causes of renal artery stenosis include:

These two conditions can affect other arteries in your body as well as your kidney (renal) arteries and cause complications.

Rarely, renal artery stenosis results from other conditions such as inflammation of the blood vessels (vasculitis), a nervous system disorder that causes tumors to develop on nerve tissue (neurofibromatosis), or a growth that develops in your abdomen and presses on your kidneys' arteries (extrinsic compression).

The first main cause of renal artery stenosis is Atherosclerosis of the renal arteries. Atherosclerosis is the buildup of fats, cholesterol and other substances (plaques) in and on your artery walls. As the deposits get larger, they can harden, reduce blood flow and cause scarring of the kidney which leads to the narrowing of the artery. Atherosclerosis is the leading cause of renal artery stenosis.

The second cause of renal artery stenosis is Fibromuscular dysplasia. In fibromuscular dysplasia, the muscle in the artery wall grows abnormally. The renal artery can narrow so much that the kidney doesn't receive an adequate supply of blood and can become damaged.

The renal artery can have narrow sections alternating with wider sections, giving a bead like appearance in images of the artery. This condition can damage one or both kidneys. At this time, experts are still not aware of the cause of fibromuscular dysplasia, but the condition is more common in women and may be something that's present at birth (congenital).

4 Making a Diagnosis

Once renal artery stenosis has been suspected, you may be referred to a cardiologist or to a nephrologist to receive a diagnosis.

It is important to make necessary preparations prior to your doctor’s appointment to make good use of the time. First, make a list of all the signs and symptoms you have including all those that you feel are unrelated or discomforts you have been feeling for a long time. List down all the medications that you have taken in the recent years includes those that you are still taking and include the dosages.

Be prepared to disclose medical information to the doctor such as past or current smoking or use of other tobacco products. It is also helpful to bring a family member or a trusted friend who can offer support and will be able to understand key points about your condition which would help remember things discussed during the appointment.

Here are some basic questions related to renal artery stenosis as having a better understanding of the condition can help you deal with the disease and treatment:

  • What's the most likely cause of my symptoms?
  • Are there any other possible causes for my symptoms?
  • What kinds of tests do I need?
  • Do these tests require any special preparation?
  • Is this condition temporary or long lasting?
  • What treatments are available, and which do you recommend?
  • What side effects can I expect from treatment? I have other health conditions.
  • How can I best manage them together?
  • Do I need to follow any dietary restrictions?
  • What about activity restrictions?
  • Is there a generic alternative to the medicine you're prescribing for me?
  • What's the appropriate level for my blood pressure?
  • Is there anything I can do to help bring it down?
  • Do you have any printed material that I can take with me?
  • What websites do you recommend?

Don’t hesitate to clarify topics related to your condition that you may find confusing. Also expect some questions from the doctor which would help them complete and understand your medical history, such as:

  • When did you first begin experiencing symptoms?
  • Are you a current or past smoker, or do you use any other type of tobacco products?
  • Does anything seem to improve or worsen your symptoms?
  • Do you know your average blood pressure values?
  • Have you had your kidney function measured?
  • Does anyone in your family have a history of high blood pressure or kidney disease?

After initial assessment, the doctor will perform a physical exam which includes listening through a stethoscope over the kidney areas for sounds that may mean the artery to your kidney is narrowed.

Blood and urine tests will be run to check your kidney function and measure the levels of hormones that regulate blood pressure.

Imaging tests commonly done to diagnose renal artery stenosis include:

  • Doppler ultrasound. High-frequency sound waves help your doctor see the arteries and kidneys and check their function. This procedure also helps your doctor find blockages in the blood vessels.
  • Computerized tomography (CT) scan. During a CT scan, an X-ray machine linked to a computer creates a detailed image that shows cross-sectional images of the renal arteries. You may receive a dye injection to show blood flow.
  • Magnetic resonance angiography (MRA). MRA uses radio waves and strong magnetic fields to produce detailed 3-D images of the renal arteries and kidneys. A dye injection into the arteries outlines blood vessels during imaging.
  • Renal arteriography. This special type of X-ray exam helps your doctor check blood flow and find the blockage in the renal arteries. Before an X-ray is taken, your doctor injects a dye into the renal arteries through a long, thin tube (catheter) to outline the arteries and show blood flow more clearly. This test is often performed at the time of restoring the blood vessel opening with a stent.
  • Running a battery of diagnostic tests will help your doctor diagnose your condition if it is indeed renal artery stenosis and come up with the appropriate treatment.

5 Treatment

Treatment for renal artery stenosis may sometimes be a combination of lifestyle changes, medication or a procedure which may be the best approach.

Treatment options may depend on the symptoms experienced and its gravity, often times constant medical monitor or observation is all that you would need.

For moderately or severely elevated blood pressure, it is recommended to make lifestyle changes such as achieving a healthy weight or lose weight if necessary, eating healthy and nutritious food, limiting salt in your diet, have regular physical activity or exercise, and reduce your stress level by engaging in relaxation exercises.

Also, you must limit or even avoid, if possible, alcohol intake or moderately drink caffeinated beverages, it is also time to stop smoking.

There are instances wherein lifestyle changes would not be sufficient to control elevated blood pressure hence medication is also prescribed.

Finding the right medication or combination of medications may require time and patience. Some medications commonly used to treat high blood pressure associated with renal artery stenosis include:

(a) Angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs), which help relax your blood vessels and block the formation or effects of a natural body chemical called angiotensin II, which narrows blood vessels.

(b) Calcium channel blockers, which help relax blood vessels.

(c) Beta blockers and alpha-beta blockers, which may have the effect of making your heart beat slowly and less forcefully or widening (dilating) your blood vessels, depending on which medication you use.

(d) Diuretics, also known as water pills, which help your body eliminate excess sodium and water.

If atherosclerosis is the underlying cause of renal artery stenosis, your doctor may also recommend aspirin and a cholesterol-lowering medication.

It is always best to keep your doctor informed on changes with the symptoms as proper medication is determined based on symptoms present.

In advanced cases of renal artery stenosis certain procedure would have to be done to manage the symptoms and prevent further kidney damage.

Those with uncontrolled high blood pressure and complication such as pulmonary edema or worsening kidney function, may need to undergo a procedure that may restore blood flow through the renal artery and improve blood flow (perfusion) to the kidney.

Procedures to treat renal artery stenosis may include:

(a) Renal artery bypass surgery. During a bypass procedure, doctors graft a substitute blood vessel to the renal artery to make a new route for blood to reach your kidneys. Sometimes this means connecting the renal artery to a vessel from somewhere else, such as the liver or spleen.

(b) Renal endarterectomy. This procedure involves removing the buildup of fats, cholesterol and other substances (plaques) from the renal artery and may be done during surgery to repair the aorta.

(c) Renal angioplasty and stenting. In this procedure, doctors open wider the narrowed renal artery and place a device inside your blood vessel that holds the walls of the vessel open and allows for better blood flow. Recent results from clinical trials that compared renal angioplasty and stenting with medication alone didn't show a difference between the two treatment approaches on reducing high blood pressure and improving kidney function.

6 Prevention

Since signs and symptoms of renal artery stenosis are only noticeable on its advance stage, prevention of further progress is by:

  • making sure that you seek regular medication check-ups,
  • notice changes in you especially possible signs and symptoms associated with the condition..

7 Alternative and Homeopathic Remedies

Two of the homeopathic or alternative remedies used for renal artery stenosis are Phosphorus and St. John’s wort. These remedies should be taken with professional advice.

8 Lifestyle and Coping

Making significant lifestyle changes is part of the treatment plan for renal artery stenosis. Your doctor will recommend maintaining a healthy weight since increase in weight leads to elevation in the blood pressure. Hence, if you are obese or overweight, it is recommended to lose at least 10 pounds to help lower your blood pressure.

Limit and even restrict salt in your diet since salt and salty foods cause fluid retention which leads to elevation in blood pressure. It is also beneficial to have a regular exercise regimen or physical activity that you will enjoy and continuously engage in.

Being physically active on a regular basis may help you lose weight, lower your risk of heart disease, lower your cholesterol and lower your blood pressure. Although physical activity is recommended but it may also be detrimental to your health hence it is best to consult your doctor first before engaging in a specific exercise program especially one that is rigorous.

Stress can also trigger elevation in the blood pressure hence find ways to reduce or avoid getting stressed. Additional healthy lifestyle changes include, moderation in drinking alcohol, quit smoking since tobacco injures blood vessel walls and speeds up the process of hardening of the arteries which causes further narrowing of the renal arteries.

9 Risks and Complications

The primary contributing factor to the development of renal artery stenosis is due to atherosclerosis, hence risk factors to renal artery stenosis is the same with atherosclerosis.

These are the risk factors for atherosclerosis of the renal arteries which are the same as for the atherosclerosis anywhere else in your body; a family history of early heart disease, Diabetes, high cholesterol, high blood pressure, aging, obesity, smoking and other tobacco use including late of physical activity or exercise.

High blood pressure (renovascular hypertension), Kidney failure, requiring treatment with dialysis or a kidney transplant, edema in your legs from fluid retention, causing swollen ankles or feet, shortness of breath due to sudden buildup of fluid in the lungs (flash pulmonary edema) are the possible complications of renal artery stenosis.