Fibromuscular dysplasia (FMD) is a vascular disease that causes abnormal cell development in the walls of one or more arteries. This can put individuals at risk for artery blockages, stroke, artery dissection (tear in an artery) or aneurysm (artery bulge).
FMD is typically found in the arteries that supply blood to the kidneys (renal arteries) and the arteries in the neck (carotid), which supply blood to the brain. FMD can also affect the arteries in the abdomen (supplying blood to the liver, spleen and intestines), extremities (supplying blood to the legs and arms) and heart (known as coronary dissection). Over half of those diagnosed with FMD have the disease in more than one artery.
Most individuals with FMD do not have a family history of the disease, although some evidence points to a genetic component, including a family history of vascular problems such as blood vessel aneurysms or dissections.
More than 90 percent of people diagnosed with FMD are women. The average age at diagnosis is 50. Possible causes of FMD include hormones, abnormal development of the arteries that supply the vessel wall with blood (resulting in inadequate oxygen supply), environmental factors and tobacco use.
FMD that causes dissections in the arteries that supply blood to the heart (coronary arteries) is often referred to as SCAD (spontaneous coronary artery dissection).
Symptoms
Symptoms of FMD vary depending on the arteries involved and how they are affected, including narrowing, dissections (tears) or aneurysms (artery bulges). Symptoms generally relate directly to the area being supplied by the diseased artery. For example, FMD in the renal arteries may cause high blood pressure. FMD in the carotid arteries may cause headaches (especially migraines), neck pain or pulsatile tinnitus (a swooshing sound in the ear).
Some patients with FMD may have vague symptoms or no symptoms at all and are diagnosed incidentally (for example, when imaging of an artery is done for another reason and FMD is discovered).
Diagnosis
FMD is typically diagnosed through imaging studies such as catheter-based angiography. During this procedure, a catheter is inserted into a large artery and advanced until it reaches the affected artery. This X-ray test uses special dye and a camera to view blood flow in the artery. Pressure inside the artery can also be measured via the catheter to help determine the severity of the blockage in the artery.
Non-invasive procedures such as computed tomography angiography (CTA) and magnetic resonance angiography (MRA) are other techniques that may be used to diagnose FMD.
Treatment Options
While there is no cure for fibromuscular dysplasia, patients with carotid or vertebral artery involvement are often prescribed aspirin to reduce the risk of stroke. Blood pressure medication helps control high blood pressure in patients with renal artery FMD.
Endovascular or surgical repair of the affected artery may also be recommended to improve blood flow.
Endovascular Treatment
Balloon angioplasty is often recommended for patients with renal artery FMD who have uncontrollable blood pressure, cannot tolerate medication or have declining kidney function. During this procedure, which widens the affected artery and improves blood flow, a balloon is inserted through a catheter into a large artery in the groin and advanced to the affected artery. The balloon is inflated to open the impaired artery.
In some cases, angioplasty may also be performed in patients with carotid or vertebral artery FMD who have severe neurological symptoms. For symptomatic patients with carotid or vertebral artery FMD who have suffered a dissection, angioplasty with placement of a stent may be performed.
Aneurysms in the arteries of the brain may be treated by catheter-based therapies such as coiling to seal off the artery bulge. During the procedure, a catheter is inserted into a large artery in the groin and fed through the artery to the affected area of the brain. A small device known as a coil is then placed in the aneurysm to prevent blood from flowing into it.
Surgical Treatment
For patients who are not candidates for angioplasty, surgery may be necessary to repair the narrowed portion of the artery. In some cases, the renal artery may be replaced or bypassed with a vein from the leg.
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