What is Fibromuscular Dysplasia?
Angiogram to diagnose FMD

Fibromuscular dysplasia (FMD) is the abnormal development or growth of cells in the walls of the body’s arteries. As a result of this growth, areas of the arteries can thicken, narrow and even enlarge, making it difficult for blood to flow through them.

FMD most often affects the renal arteries, which supply the kidneys with blood, and carotid arteries, which bring blood to the brain. Less commonly, FMD develops in the arteries of the abdomen (mesenteric arteries) or the arteries of the arms and legs. In nearly one-third of people with FMD, more than one artery is affected.

Depending on which arteries are affected, FMD can increase the risk of high blood pressure, impaired kidney function, aneurysm, stroke and other complications. FMD affects between 1-5% of Americans, typically women under age 50.

What Causes Fibromuscular Dysplasia?

The cause of FMD is still unknown. However, several factors may play a role in its development. A combination of these factors is likely responsible:

  • Genetics: Research suggests that about 10% of cases appear in families. People who have a family member with FMD may develop the condition in different arteries than their relative, experience a more or less severe version of the disease, or may not develop FMD at all
  • Hormones: FMD is three to four times more common in premenopausal women than in men, suggesting that sex hormones may be involved in its development
  • Abnormal arteries: A lack of oxygen to the artery walls may cause them to form abnormally. Arteries may also be located abnormally within the body, predisposing them to FMD
What Conditions are Associated with Fibromuscular Dysplasia?

FMD can increase risk of several conditions, including:

  • High blood pressure: When the arteries become narrowed, blood pressure can increase. High blood pressure (hypertension) is the most common complication of FMD
  • Stroke: A stroke may occur if an aneurysm in one of the carotid arteries ruptures or if one of the carotid arteries dissects, disrupting the flow of blood to the brain
  • A tear in the artery (dissection):The lining of the artery wall may tear, causing blood to leak into the wall
  • Aneurysm: The pressure of blood flow through a narrowed artery can create a weakened area or bulge in the artery wall called an aneurysm. An aneurysm may rupture, resulting in a life-threatening situation
  • Pain or cramping in lower legs (intermittent claudication): FMD that affects the arteries in the legs can cause discomfort or pain when walking and exercising
  • Kidney dysfunction or failure: Reduced blood flow to the kidneys can impair kidney function and, in rare cases, lead to kidney failure
What are the Risk Factors for Fibromuscular Dysplasia?

Risk factors for FMD include:

  • Gender: FMD affects more women than men
  • Age: FMD is most common in premenopausal women younger than age 50
  • Family history: FMD appears to have a genetic basis. About 10% of people with FMD have a relative with the condition
What are the Symptoms of Fibromuscular Dysplasia?

Many people with FMD do not develop symptoms. When symptoms do occur, they depend on the location of the affected arteries.

In the renal arteries, FMD can cause:

  • High blood pressure
  • Shrinkage (atrophy) of the kidney, which is often painless
  • Impaired kidney function

In the carotid arteries, FMD can cause:

  • Dizziness
  • Ringing in the ears
  • Headache
  • Blurred vision or temporary loss of vision
  • Neck pain
  • Stroke

In the mesenteric arteries, FMD can cause:

  • Abdominal pain after eating
  • Unintended weight loss

In the arteries of the arms and legs, FMD can cause:

  • Discomfort in the affected limb(s) when walking /running
How is Fibromuscular Dysplasia Diagnosed?

In addition to a complete medical history and physical examination, physicians may use one or more the following tests to diagnose FMD:

  • Computed tomography angiography (CTA): This test uses a combination of X-rays, contrast dye and computer technology to produce cross-sectional images of the body
  • Duplex ultrasonography: This technique uses high-frequency sound waves and a computer to create images of blood vessels, tissues and organs. Duplex ultrasonography is used to measure and assess the flow of blood
  • Magnetic resonance angiography (MRA): This noninvasive procedure that uses a combination of a large magnet, radiofrequencies and a computer to produce detailed images of organs and structures within the body
What is the Treatment for Fibromuscular Dysplasia?

Even though there is no cure for FMD, it can be controlled. A multidisciplinary team of physicians will determine the best treatment based on the patient’s individual case. Treatment for FMD includes:

  • Medical therapy: The physician may prescribe medications to help control high blood pressure, including ACE inhibitors, beta blockers and calcium channel blockers. People with FMD may also need to take antiplatelet drugs, such as aspirin, to prevent blood clots
  • Interventional therapy: Physicians may use percutaneous transluminal angioplasty (PTA) to open narrowed sections of arteries. In this technique, a balloon-tipped catheter (thin, flexible tube) is threaded through the affected artery to expand it. PTA is less invasive than open surgery and results in faster recovery times
  • Surgery: This intervention re-routes blood flow around the diseased artery and may be used in severe cases or when PTA is not an option.
  • Genetic counseling: Because FMD appears to run in families, women of childbearing age may receive counseling for the genetic basis of the condition. There is not yet a genetic test for FMD.
  • Psychosocial treatment: FMD often affects young, otherwise healthy women, and coping with it can be difficult. Psychologists or other mental health professionals can offer counseling to help patients deal with the stress and anxiety that may accompany having FMD
  • Obstetrics/gynecological care: Specialists in obstetrics and gynecology can advise patients with FMD about the use of oral contraceptives, estrogen therapy and other hormone-based medications, which can affect blood flow in the arteries
How Long Will Treatment for FMD continue?

Although FMD can be managed successfully, it can reoccur in some patients. For this reason, people with FMD should continue to be monitored by their physicians even after interventional or surgical treatments are completed. Patients may be seen for follow-up visits every few months or once or twice a year, depending on their individual case. Physicians will monitor patients’ medications and assess signs of possible recurrence.

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