FMD Info

What Causes FMD?

FMD was first diagnosed in 1938 and the cause is not yet known, but several theories have been suggested. A number of case reports in the literature have identified the disease in multiple members of the same family including twins. As a result, it is felt that there may be a genetic cause. However, a relative may have different artery involvement, different disease severity, or not develop FMD at all. In fact, most individuals with FMD do not have a family member who also has the disease. Among some individuals with FMD, there is a family history of other vascular problems, such as blood vessel aneurysms.

FMD is far more commonly seen in women than in men, resulting in the theory that hormones may play an important role in disease development. However, in small population studies, one's reproductive history (number of pregnancies and when they occurred) as well as the use of birth control pills did not correlate with the development of FMD.

Other possible causes of FMD include abnormal development of the arteries that supply the vessel wall with blood, resulting in inadequate oxygen supply; the anatomic position or movement of the artery within the body, certain medications, and tobacco use. It is possible that many factors contribute to the development of FMD. This area requires further research and is under investigation by many researchers around the world.

What are the signs and/or symptoms of FMD?

Coronary Artery FMD and Spontaneous Coronary Artery Dissection (SCAD)

FMD can affect the arteries of the heart – also called the coronary arteries. Similar to FMD in other arteries, FMD of the coronary arteries can cause abnormal areas of narrowing (stenosis) or tearing (called dissection). Both stenosis and dissection from FMD can lead to reduced blood flow in the coronary arteries, which can cause chest pain or in some people very rarely it can cause heart attack.

Recently, studies have shown that a high percentage of women who were healthy and who have a sudden tearing of a coronary artery (called Sudden Coronary Artery Dissection or "SCAD") probably have undiagnosed FMD. SCAD was previously thought to be a separate condition to FMD, but now we are starting to understand that many people have FMD as the main reason for their coronary tear. Like FMD in the rest of the body, SCAD is most common in middle aged females. However, it also seems that women are more likely to have a sudden coronary artery dissection within weeks of childbirth. For more information on SCAD please follow this link to the 2018 AHA Scientific Statement.

Beadie Fun Fact

SCAD has been shown to be associated with increased arterial tortuosity

Who has FMD?

How common is FMD?

It is difficult to determine how common FMD is in the general population, due to a number of reasons. Individuals with mild FMD are often asymptomatic and so the disease often goes undetected. Most studies examining the prevalence of FMD have looked at specific patient populations in whom individuals may have already suffered from serious consequences of the disease, such as patients with carotid dissection. Since there is a delay in diagnosis of FMD among FMD patients and since there may be decreased awareness of signs and symptoms of FMD among health care providers, it is likely that FMD is underdiagnosed and is more common than previously thought.

Beadie Fun Fact

The prevalence of renal FMD in the general population is unknown because this disease is often clinically silent or discovered incidentally

How can FMD be diagnosed?

In order to diagnosis FMD, a test must be done to image the blood vessels. There are many options for imaging the arteries, including specialized blood vessel ultrasound known as duplex ultrasound, a CAT scan of the arteries which is obtained after a dye is given through the veins, or a special type of MRI. In many cases, the diagnosis of FMD requires that a procedure known as an arteriogram be performed. Arteriography is a procedure that is performed by a radiologist, vascular surgeon, cardiologist, or vascular medicine specialist with appropriate training. It involves inserting a wire through the groin into or near the affected artery and injecting contrast material, a dye that can be detected by an x-ray machine. The patient is usually awake during an arteriogram procedure although medications may be given to keep her comfortable. This outpatient procedure usually lasts from one to two hours with a recovery period of up to six hours (this varies widely). The experience and expertise available at your medical institution will play an important role in what diagnostic options are available to you.

Beadie Fun Fact

There are currently no genetic tests that are specific to FMD

What kind of treatment is there for FMD?

There is no cure for FMD. Treatments are focused on managing symptoms and complications of FMD, including high blood pressure and headaches. Antiplatelet medications, such as aspirin, may be prescribed along with medications to treat high blood pressure (anti-hypertensives). Many patients with FMD suffer from headaches, and a number of medications are available to help control and prevent headaches. All patients with FMD who use tobacco should be encouraged to quit.

In some cases of FMD, an attempt should be made to improve the flow of blood through a severely narrowed vessel. The kind of treatment used for narrowing due to FMD depends largely upon which arteries are affected and the presence and severity of the symptoms. In most cases, such procedures are done using balloon angioplasty; a procedure known as percutaneous transluminal angioplasty (PTA). PTA is often performed at the same time as an arteriogram.

If an angioplasty is performed, a catheter is extended into the affected artery and a small balloon is inflated in the artery. A metal stent is typically not required to keep the vessel open, but may be needed in some cases, such as for treatment of a dissection (tear) of a blood vessel. If angioplasty is performed, the procedure and recovery period may be longer than an arteriogram done for diagnosis only. Occasionally, traditional open surgery is performed to treat severe narrowing due to FMD, particularly in those that cannot be treated with angioplasty.

Patients with FMD who are found to have a significant aneurysm within the brain or renal arteries may need to undergo surgery even without symptoms. In such cases, it is recommended that the aneurysm be treated to prevent rupture which can be potentially life threatening. The type of treatment for an arterial aneurysm depends on its location and size. Treatment options for aneurysms include traditional open surgery or a less invasive angiogram-based procedure which treats the aneurysm using special vascular coils and/or stents.

The appropriate treatment will vary with each individual and severity, location, and extent of disease. The treatment plan should be discussed in depth with a specialist who is very knowledgeable about FMD and its natural history.

Beadie Fun Fact

In 2019, multi-specialty groups from Europe and the United States published a consensus statement regarding FMD