FMD: Another Type of Blocked Artery

It’s better known to some physicians as FMD, which is much easier to say than its medical name “Fibromuscular Dysplasia.”

Unfortunately, the condition itself —  which commonly affects mostly women in their 40s — is not so well known among primary doctors and non-vascular specialists.

Fibromuscular Dysplasia is a disease that is characterized by abnormal cell development in the walls of different arteries.  As a result, areas of narrowing (called stenosis), aneurysms, or tears (called dissections) may occur.  Many people with FMD do not have any symptoms or signs, and are diagnosed by accident during a radiology scan for another problem.

High blood pressure is one of the most common findings in FMD.  High blood pressure develops in FMD when the arteries that carry blood to the kidneys become narrowed because of the growth abnormalities in the wall. FMD can lead to stroke when fibrous growths occur in the arteries that take blood to the brain.

“FMD is a non-inflammatory vascular disease of unknown cause that predominantly affects young women, but symptoms can range from no symptoms to stroke and death,” said Ian Del Conde, M.D., a specialist in vascular medicine and cardiovascular disease who helps run one of eight FMD clinics in the U.S. at Baptist Cardiac & Vascular Institute.

In most cases (up to 75 percent of patients), FMD affects the arteries that supply blood to the kidneys (renal arteries).

But it can also affect the artery in your neck that supplies blood to the brain — the carotid artery. Sometimes it affects other arteries, such as those to the arms and legs or to the abdomen.

‘Swooshing’ in the Ears
In a small percentage of women who are afflicted with FMD of the carotid, a potentially debilitating symptom is a buzzing or “swooshing” noise in the ears. That noise can come and go, or persist through the day.

“A very peculiar symptom of carotid FMD is a ‘swooshing’ in their ear,” said Dr. Del Conde. “It can be very debilitating and patients can have a hard time sleeping. Many times these patients have gone to different specialists, like ENTs (ear, nose, and throat specialists), and they haven’t found anything. Sometimes a doctor will simply say it’s nothing and not to worry.”

But FMD should be a concern.

That “swooshing” sound is actually “turbulence in the blood flowing through the carotid,” Dr. Del Conde said. The potential for a stroke is present until the condition is diagnosed and treated with aspirin.

An arteriography/angiography, which is an X-ray picture of the arteries, is most often used to diagnose FMD. Diagnosis methods also include other types of imaging studies, such as MRI, ultrasound and CT scan. In most FMD cases, the affected artery will be seen as a “string of beads.” The X-ray may also show the narrowing of the arteries without the string of beads.

‘Beads of Blood Vessels’
“The physician and imaging technician need to look for something very specific to diagnose FMD,” said Dr. Del Conde. “You most commonly see a string of beads of blood vessels, instead of smooth arteries.”

In certain cases, an angioplasty of the renal arteries is recommended for patients with FMD that affects the blood supply to the kidneys. Similar to the procedure used to treat blockages in the heart’s arteries, renal angioplasty involves placement of a balloon-mounted catheter inside the artery at the site of a narrowing or blockage.

The Institute is taking part in the U.S. FMD Registry. The registry draws from 10 participating institutions and has grown from 447 cases in 2012 to more than 1,000 currently.

“The registry is where some of the best information about FMD is coming from,” Dr. Del Conde said. “Before the registry, we had a few small cases here and there reported from around the world. This is important because we estimate that about 5 percent of the population could have a form of FMD.”