What is Fibromuscular Dysplasia?

Fibromuscular dysplasia (FMD) is a condition characterized by a narrowing of the arteries due to the growth of clusters of abnormal cells within the artery walls. The condition can lead to a variety of complications, including high blood pressure and an increased risk for aneurysm. There is no cure for FMD and treatment options generally include drug therapy and the surgical repair of the narrowed artery.

In most cases, individuals with fibromuscular dysplasia are asymptomatic, meaning they experience no symptoms. Oftentimes, symptoms associated with FMD that do manifest are dependent on the location and extent of the narrowed artery. Fibromuscular dysplasia commonly occurs in the walls of arteries leading to major organs, including the kidneys and brain. Artery walls located in the extremities, such as the legs and arms, may also contain abnormal clusters of cell growth.

Individuals whose arteries to the kidneys are affected by FMD may experience high blood pressure, chronic kidney failure, and the death of the kidney tissue, known as ischemic renal atrophy. In people whose FMD affects the arteries leading to the brain, symptoms may include chronic neck discomfort, dizziness, and a ringing in the ears, also known as tinnitus. Signs that FMD may be affecting a person's abdomen or extremities may include abdominal discomfort, numbness or coldness in the limbs, and physical weakness. It is possible for more than one artery to be affected by FMD.

There are a variety of tests utilized to confirm a diagnosis of fibromuscular dysplasia. Initially, a physical examination and blood test may be conducted prior to more extensive testing. Individuals whose symptoms seem to be indicative of FMD may undergo additional testing that may include a computerized tomography (CT) angiogram, a Doppler ultrasound, and magnetic resonance imaging (MRI). Imaging testing allows for a closer, noninvasive examination of the affected area to determine if there is a narrowing of the arteries. Once a diagnosis is made, periodic testing may be conducted to evaluate the progression of the individual’s condition.

Treatment for fibromuscular dysplasia is dependent on the individual’s overall health and the location of the narrowed artery. Surgical repair of the narrowed artery is usually recommended in combination with a prescription medication regimen to restore proper blood flow and alleviate symptoms. Procedures utilized to restore proper artery function include a percutaneous transluminal renal angioplasty (PTRA) and surgical revascularization.

A percutaneous transluminal renal angioplasty may be conducted during a CT angiogram. The procedure involves the insertion and inflation of a balloon in the narrowed part of the artery, which serves to improve blood flow. The procedure generally takes up to two hours to complete and is performed while the individual is conscious. A mild sedative is administered to keep the individual relaxed.

When PTRA is not a viable treatment option due to a severe narrowing of the artery, a surgical revascularization may be performed to restore proper blood flow. Conducted under general anesthesia, the type of procedure used is wholly dependent on the location and extent of damage to the affected artery. In cases where there is a risk of aneurysm, a metal stent may be employed to support the weakened artery and prevent rupture.

Drug therapies associated with FMD treatment may include the use of beta blockers, calcium channel blockers, and angiotensin-converting enzyme (ACE) inhibitors. The goal of drug therapy in most cases is to regulate and manage blood pressure. There is the potential for adverse side effects associated with the use of such drug therapies, including impaired kidney function. Periodic urinalysis and blood tests may be administered to monitor kidney function.

Though there is no single, definitive cause for the development of fibromuscular dysplasia, it has been asserted that genetics and hormones may contribute to the progression of the disease. Premenopausal women seem to be at the highest risk for developing FMD. Individuals who smoke also have an increased risk for becoming symptomatic. Complications associated with FMD include stroke, chronic kidney failure, and aneurysm.