Renovascular Hypertension

What is renovascular hypertension?

Renovascular hypertension is high blood pressure due to poor blood flow to the kidneys.

How does it occur?

Any disease that causes less blood to flow to one or both kidneys may cause high blood pressure. When too little blood gets to the kidneys, they produce more of an enzyme called renin. When renin is released into the bloodstream, it ends up being converted into an enzyme that makes the body retain sodium and water. If you have narrowed blood vessels and too much sodium and water in the body, your blood pressure may get higher--sometimes much higher.

One of the most common causes of poor blood flow to the kidneys is atherosclerosis (hardening of the arteries). When arteries to the kidneys narrow and harden they block the flow of blood.

Another cause is fibromuscular disease. Fibromuscular disease, also called fibromuscular dysplasia, causes fibrous tissue to grow in the walls of the kidney arteries. This makes the walls thick and narrows the arteries.

Tumors around the kidney or other conditions that put pressure on the kidney arteries also may reduce blood flow and cause high blood pressure.

What are the symptoms?

High blood pressure usually does not cause symptoms. Your provider may suspect renovascular hypertension if you:

• start having high blood pressure before you are 30 or after age 55
• have high blood pressure that gets worse while you are taking blood pressure medicine
• have high blood pressure and your kidneys don't work as well as they should.

How is it diagnosed?

Several kinds of tests may be done:

• Ultrasound. This is the most common test. It uses high-energy sound waves to take pictures of the kidneys and the arteries to the kidneys. The pictures may show narrowing in the kidney arteries.
• Captopril test. This test measures whether the blood pressure drops after you are given a medicine called captopril.
• Renography. For this test, a radioactive tracer liquid is injected into a vein. Special cameras can then measure blood and urine flow in the kidneys.
• Magnetic resonance arteriography. This test uses a powerful magnetic field and a computer to create pictures of the arteries around the kidney.
• Renal arteriogram. For this X-ray test, dye is injected into an artery to make sure it is not blocked or narrowed. Injecting the dye carries a very slight risk of damaging the ability of your kidneys to filter blood. Your healthcare provider will suggest this test only when he or she thinks it is needed.

How is it treated?

Renovascular hypertension may be treated with medicine or surgery.

As long as kidney function stays normal, treatment with blood pressure medicine may work very well. About 75 to 80% of people with renovascular hypertension can control it with medicine. The medicines used most often used are ACE inhibitors. Other types of blood pressure drugs may also be used.

Surgery may be needed for better blood flow to the kidneys. The surgeon either removes the blockage in the artery or bypasses the blocked blood vessel with a graft.

Renal artery angioplasty is another way to restore blood flow to the kidneys. A deflated balloon is attached to the tip of a tube (catheter). The catheter is put into a groin artery. It is then guided to the narrowed part of the kidney artery. The balloon is inflated to open the artery. The balloon is then deflated and the catheter removed. Angioplasty causes less discomfort than surgery and requires only a short hospital stay.

You may still need to take blood pressure medicine after surgery or angioplasty.

How long will the effects last?

Often control of hypertension requires taking medicine for the rest of your life, even if you have surgery. If high blood pressure is not treated, it often leads to serious problems, including stroke, heart attack, and kidney failure. It is very important to follow your healthcare provider’s directions and take your medicine as prescribed.

How can I help take care of myself?

• If you have renovascular hypertension, see your healthcare provider as often as he or she recommends. Your provider needs to make sure that the disease does not get worse or come back or affect the other kidney. Since high blood pressure often does not cause symptoms, checkups are the best way to be sure that your treatment is working.
• Always follow your healthcare provider's instructions for taking medicines. Don’t miss any doses and don’t take less medicine or stop taking medicine without talking to your provider first. It can be dangerous to suddenly stop taking blood pressure medicine. Also, do not increase your dosage of any medicine without first talking with your provider.
• Ask your healthcare provider or pharmacist for information about the drugs you are taking.
• Ask your provider about nonprescription medicines and supplements before you take them.
• Do not smoke.
• Keep a healthy weight. Lose weight if you need to.
• Follow the DASH diet. This diet is low in fat, cholesterol, red meat, and sweets. It is rich in fruits, vegetables, and low-fat dairy foods. The DASH diet also includes whole-grain products, fish, poultry, and nuts.
• Use less salt. Check the levels of sodium listed on food labels. Avoid canned and prepared foods unless the label says no salt is added.
• Limit the amount of alcohol you drink.
• Limit the amount of caffeine you drink.
• With your provider's approval, start an exercise program that you can do regularly (such as biking or walking).
• Check your blood pressure (or have it checked) as often as your provider advises. Keep a chart of the readings.
• Try to reduce the stress in your life or learn how to deal better with situations that make you feel anxious.