Fibromuscular dysplasia (FMD) is a condition in which at least one of your arteries has an abnormal cluster of cells growing in the artery wall. This cluster causes the artery to narrow, which can cause damage to the organs that receive blood through the narrowed artery. Fibromuscular dysplasia can cause a number of complications, such as high blood pressure and aneurysms, if left untreated.

Fibromuscular dysplasia appears most commonly in the arteries leading to the kidneys. Fibromuscular dysplasia can also affect the arteries leading to your brain, abdomen, arms, and legs. While there isn't a cure for fibromuscular dysplasia, it can be treated effectively.

Most people who have fibromuscular dysplasia don't have any symptoms. Still, it's possible you could have some symptoms of the disease, depending on what artery is affected by fibromuscular dysplasia.

If the arteries to your kidneys (renal arteries) are affected, you may have:

• High blood pressure
• Tissue death in your kidney (ischemic renal atrophy)
• Chronic kidney failure

If the arteries to your brain (carotid arteries) are affected, you may have:

• Dizziness
• Blurred vision or temporary loss of vision
• Ringing in your ears (tinnitus)
• Neck pain
• Chronic headaches

If the arteries to your abdomen (mesenteric arteries) are affected, you may have:

• Abdominal pain after eating
• Unintended weight loss

If the arteries to your arms or legs (peripheral arteries) are affected, you may have:

• Discomfort when moving your arms, legs, hands or feet
• Cold limbs
• Weakness
• Numbness
• Skin changes in color or appearance

About a quarter of people with fibromuscular dysplasia have more than one narrowed artery.

When to see a doctor
If you have any of the signs or symptoms listed and are concerned about your risk of fibromuscular dysplasia, see your doctor. Because fibromuscular dysplasia tends to be hereditary, tell your doctor about your family history of the disease, even before you show any symptoms. A genetic test is not yet available for fibromuscular dysplasia. Screening for fibromuscular dysplasia is not possible either, since it could occur in any of your arteries.

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Fibromuscular dysplasia

While the cause of fibromuscular dysplasia is unknown, it's believed that several factors may play a role.

• Genetics. The cause of fibromuscular dysplasia isn't known, but it's thought that genetics plays a role. But, if another family member has fibromuscular dysplasia, you or a relative may never get fibromuscular dysplasia, or you might get the condition in a different artery or have a milder case or a more severe case than your family member. A genetic test is not yet available for fibromuscular dysplasia.
• Hormones. Because premenopausal women have fibromuscular dysplasia more often than men do, hormones may play a role in the development of fibromuscular dysplasia. However, fibromuscular dysplasia is not linked to how many children a woman has, when she gives birth or whether she's taken birth control pills.
• Abnormally formed arteries. Fibromuscular dysplasia could be caused by inadequate oxygen to the arteries that supply your blood vessel walls with blood, which causes the vessels to form abnormally. It could also be caused if the position of your arteries in your body is abnormal, or if a medication or tobacco causes your arteries to develop abnormally. Once the artery develops abnormally, a cluster of cells builds in the artery wall, narrowing it and reducing blood flow.

The most common form of fibromuscular dysplasia results in a "string of beads" appearance of the artery. Other, more aggressive forms of fibromuscular dysplasia have a smooth appearance.

Premenopausal women ages 14 to 50 are most likely to develop fibromuscular dysplasia, although older women and young adult men also can develop the condition. It's believed that fibromuscular dysplasia has a genetic link, although researchers don't know what genes could cause the condition.

Tobacco use and some medications may cause irritation in an artery, and cause the changes in blood flow to become more severe.

Fibromuscular dysplasia can cause a number of complications. These include:

• High blood pressure. The most common complication of fibromuscular dysplasia is high blood pressure. The narrowing of the arteries causes higher pressure on your artery walls, which can lead to further artery damage or heart failure.
• Chronic kidney failure. If the artery to the kidney is narrowed by fibromuscular dysplasia, you may not get enough blood flow to your kidney, causing permanent kidney injury.
• Dissected artery. Fibromuscular dysplasia can cause tears in the walls of your arteries, causing blood to leak into the artery wall.
• Aneurysms. When your arteries are narrowed, the blood flow can weaken the wall of your arteries, creating a bulge called an aneurysm. If an aneurysm ruptures, it can be a life-threatening emergency. An aneurysm can occur with fibromuscular dysplasia in an artery leading to the kidneys, brain, abdomen, arms or legs.
• Stroke. If you have a dissected artery leading to your brain or if an aneurysm in an artery to your brain ruptures, you can have a stroke.

If you have a family history of fibromuscular dysplasia, tell your doctor. Because most people who have fibromuscular dysplasia don't have any symptoms, it's unlikely your doctor would first check for fibromuscular dysplasia unless you have a family history of the condition.

To diagnose fibromuscular dysplasia, your doctor may order one or more imaging tests to see your arteries. You may need to fast for several hours before the tests, depending on where the narrowed arteries are in your body. Your doctor should give you instructions before your tests. Talk to your doctor if you have any additional questions about preparing for your tests.

Before you're tested for fibromuscular dysplasia, your doctor may also want to check for atherosclerosis, another condition that can narrow your arteries. Tests for atherosclerosis usually include a physical exam and a fasting blood test to check your blood sugar and cholesterol levels.

The tests you'll have to diagnose fibromuscular dysplasia could include:

• Doppler ultrasound. Doppler ultrasound can determine if an artery is narrowed by fibromuscular dysplasia. In this noninvasive test, an instrument called a transducer is pressed to your skin. The transducer produces high-frequency sound waves, which bounce off red blood cells. A Doppler ultrasound can estimate how fast blood flows by measuring the rate of change in its pitch (frequency). If the ultrasound shows your blood is moving slowly through an artery, it may be due to fibromuscular dysplasia.
• Computerized tomography (CT) angiogram. A CT angiogram allows your doctor to check your arteries to see if they're narrowed or blocked. You'll receive an injection of a radioactive dye, and the doughnut-shaped CT scanner will be moved to take images of the artery your doctor believes is narrowed. The images are then sent to a computer screen for your doctor to view.
• Magnetic resonance imaging (MRI). This test allows your doctor to see the soft tissues in your body. During an MRI, you lie on a table inside a long tube-like machine that produces a magnetic field. The magnetic field aligns atomic particles in some of your cells. When radio waves are broadcast toward these aligned particles, the particles produce signals that vary according to the type of tissue they are. Using the images from the test, your doctor may be able to see the cluster of cells narrowing your artery.
• Digital subtraction angiogram. This test is used to check for fibromuscular dysplasia of the kidney. In this test, you'll first have an X-ray taken of the part of your body where your artery may be narrowed. Then you'll receive an injection of a radioactive dye to darken your arteries. Your doctor will then take another X-ray and digitally remove other tissues and blood vessels from the X-ray image. This allows your doctor to clearly see the artery that may be affected. This test is the best way to check for fibromuscular dysplasia, but it's also the most invasive. Digital subtraction angiogram is usually the last in the series of tests you'll have to check for fibromuscular dysplasia.

Once you've been diagnosed with fibromuscular dysplasia, your doctor may repeat a Doppler ultrasound exam or a CT angiogram every six to 12 months to see how your condition is progressing.

Treatment for fibromuscular dysplasia depends on your health, the location of the narrowed artery and other underlying conditions you have, such as high blood pressure. Treatment with medications is recommended for most people with fibromuscular dysplasia, including those who have procedures to restore the blood flow.

Medical procedures and surgery
For otherwise healthy people with fibromuscular dysplasia, repairing the affected vein or artery is often recommended. The procedures to improve blood flow can include:

• Percutaneous transluminal renal angioplasty (PTRA). This procedure is often performed at the same time as a digital subtraction or CT angiogram. Once the dye from the angiogram shows the narrowed area of the artery, a wire is threaded to the artery and a catheter with a balloon is inserted in the narrowed area. The balloon is then inflated to open the narrowed part of the artery. Unlike the angioplasty procedures performed on people with heart disease, a stent is usually not necessary to keep the artery open.

  PTRA is usually performed while you're awake, although you'll be given a sedative to relax during the procedure. The procedure takes about one to two hours.

• Surgical revascularization. If PTRA is not an option, and the narrowing of your arteries is severe, your doctor may recommend more invasive surgery to repair the narrowed portion of the artery. The type of surgery you'll need depends on the location of the narrowed artery and how damaged the artery is. These procedures require general anesthesia, meaning you'll be asleep during the surgery.

  If your doctor finds other damage related to fibromuscular dysplasia, such as an aneurysm, he or she may also recommend placing a metal mesh tube (stent) inside the weakened part of the artery to try to stop it from rupturing.

Drugs
Treatment with high blood pressure medications is recommended for most people with fibromuscular dysplasia, even if you also have a procedure to correct your condition. These could include medications from several categories:

• Angiotensin-converting enzyme (ACE) inhibitors, such as benazepril (Lotensin), enalapril (Vasotec) or lisinopril (Prinivil, Zestril), to stop the narrowing of your blood vessels
• Calcium channel blockers, such as amlodipine (Norvasc) or nifedipine (Adalat, Procardia) and others, to prevent calcium from entering your heart and blood vessel walls
• Beta blockers, such as metoprolol (Lopressor, Toprol-XL) or atenolol (Tenormin) and others, to slow your heartbeat and block adrenaline

Because some of these drugs can affect the way your kidneys work, your doctor may recommend blood tests and a urine test (urinalysis) to make sure your kidneys are still functioning correctly.

Fibromuscular dysplasia is not preventable. If you smoke, quitting can reduce your likelihood of developing fibromuscular dysplasia or making the condition worse.