What is fibromuscular dysplasia?
Fibromuscular dysplasia (FMD) is a rare medical condition. Patients with FMD have abnormal cellular growth in the walls of their medium and large arteries. This can cause the arteries with the abnormal growth to look beaded. The arteries may also become narrow (stenosis).
Most cases of FMD affect the carotid and renal arteries. The carotid arteries are in the neck and connect the heart and the brain. The renal arteries are the blood vessels that carry blood from the aorta to the kidneys.
Fibromuscular dysplasia can also affect the arteries to the intestines (the mesenteric arteries), the arteries to the legs or arms, the coronary arteries (arteries that supply blood to the heart), and arteries in other parts of the body, although this is less common. Many times, arteries in more than one location are affected by FMD.
Who is affected by FMD?
Fibromuscular dysplasia is most common in women between the ages of 40 of and 60, but the condition can also occur in children and the elderly. The majority (more than 90%) of patients with FMD are women. However, men can also have FMD, and those who do have a higher risk of complications such as aneurysms (bulging) or dissections (tears) in the arteries.
What causes FMD?
Despite a great deal of research, it is still not clear what causes FMD. It is very likely that FMD has multiple underlying causes. Some of the factors that may play a role include:
- Hormonal influences: The disease occurs most commonly in women.
- Genetics: About 7-11% of cases are inherited. Some patients with FMD also have genetic abnormalities that affect the blood vessels.
- Internal mechanical stress, including trauma to the artery walls or mechanical forces on the vessel.
- Loss of oxygen supply to the blood vessel wall: This occurs when the tiny blood vessels in the artery walls that supply them with oxygen-rich blood get blocked by fibrous lesions.