Fibromuscular Dysplasia (FMD)

FMD is a non-inflammatory, non-atherosclerotic disorder. Meaning it is not caused by inflammation or plaque buildup. FMD causes narrowing or blockage of specific arteries in your body and also can lead to bulging of an artery caused by weakening of the artery wall (“aneurysm”) or a tear in the artery (“dissection”).

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Coronary Artery Disease (CAD) is usually caused by fatty deposits (plaque) laid down in the artery walls. The deposits are encouraged by high blood pressure, high blood levels of cholesterol, tobacco smoking, and diabetes. Cholesterol-lowering medicines are often prescribed for people with CAD. However, sometimes arteries are narrow for other reasons and a condition called Fibromuscular Dysplasia (FMD) is impacting women disproportionately – in fact, women represent 90% of FMD cases.

Why does this matter? Because the treatments we prescribe for CAD versus FMD may differ. A treatment strategy for FMD may include different medications such as medicine for blood pressure and clots, or even require vascular procedures such as angioplasty or surgery.

What is FMD?

FMD is a non-inflammatory, non-atherosclerotic disorder. Meaning it is not caused by inflammation or plaque buildup. (Circulation 2012)

FMD causes narrowing or blockage of specific arteries in your body and also can lead to bulging of an artery caused by weakening of the artery wall (“aneurysm”) or a tear in the artery (“dissection”).

When FMD causes arteries to narrow, the blood flow through those arteries is reduced, and the loss of blood flow to the organs can affect their function. The arteries commonly affected by FMD are the ones from the heart to the kidneys (“renal arteries”), as well as the carotid and vertebral arteries, which provide blood flow to the brain.

About two-thirds of patients with FMD have multiple arteries involved.

What Causes FMD?

The cause of FMD is still unknown and progress has been slow in understanding the epidemiology, pathogenesis and outcomes since its first description in 1938. It is now a subject of research investigation at The Texas Heart Institute (THI). We are beginning to recognize common features like abnormal cell development in the artery wall. And some factors like genetic predisposition, hormonal influence, mechanical factors (stretching of smooth muscle cells and trauma to the blood vessel wall), and ischemia of the blood vessel wall could predispose people to the disease.

What are the symptoms?

In patients with FMD, symptoms can vary from none at all to any of the following:

Artery affected	Symptoms
Kidney artery (Renal artery)	High blood pressure Tissue damage in your kidneys (revealed by blood test results: elevated creatinine or a drop in glomerular filtration rate [GFR]) Chronic kidney failure (rare)
Brain arteries (Carotid and vertebral arteries)	Dizziness Headache, neck pain Blurred vision or temporary loss of vision Pulsating ringing in your ears (tinnitus) Facial weakness or numbness Signs of stroke or transient ischemic attack
Heart arteries (Coronary arteries)	Chest pain Heart attack (rare)
Abdominal arteries (Mesenteric, celiac, hepatic arteries)	Abdominal pain after eating Unintended weight loss
Arteries leading to your extremities (Peripheral arteries)	Discomfort when moving your arms, legs, hands or feet Cold limbs Weakness Changes in color or appearance of skin Numbness

How is FMD diagnosed?

The most common tests used to diagnose FMD non-invasively are CT scan with contrast and ultrasound with Doppler. These exams will determine if the artery is narrowed and show the typical pattern “string of beads.”

What are the risk factors for FMD?

Some factors that can increase a person’s risk of developing FMD are:

Gender: Women have a greater risk of FMD – 90% of patients with FMD are women.
Age: In the past, FMD was identified as a disease of young women, but lately this has changed. According to the United States FMD Registry, the average age at diagnosis is 52 years, with a range of 5 to 86 years.
Smoking: Smoking increases a person’s risk of developing FMD. For people already diagnosed with the disease, smoking is a risk factor for more serious FMD.

Are there any complications?

High blood pressure: This is the most common complication. The narrowing of the arteries causes higher pressure on your artery walls, which can lead to further artery damage, heart disease or heart failure.

Dissected artery: One possible complication of FMD is a tear in the wall of your heart arteries (coronary arteries), causing a leak. This is known as arterial dissection or spontaneous coronary artery dissection (SCAD). The signs and symptoms of SCAD are shortness of breath, nausea, sweating and chest pain. Also, SCAD can cause heart attack.

Aneurysms: FMD can weaken the walls of your arteries, creating a bulge called an aneurysm. If an aneurysm ruptures, it can be a life-threatening emergency.

Stroke: If you have a dissected artery leading to your brain, or if an aneurysm in an artery to your brain ruptures, you can have a stroke. High blood pressure can also increase your risk of stroke.