Fibromuscular dysplasia (FMD), or fibromuscular dysplasia of arteries, is a disease that can cause stenosis of the renal arteries, carotid arteries, and less commonly, the arteries of the abdomen. The disease can cause hypertension, strokes, and arterial aneurysm and dissection.
In individuals with FMD, the walls of one or more arteries undergo dysplasia. Due to this abnormal cellular development, the vessels may become stenosed. A sufficient decrease in blood flow through the artery can cause symptoms. However, FMD is often diagnosed incidentally in the absence of any signs or symptoms during an imaging study. Angiography with contrast will show a characteristic "string of beads" morphology in a vessel affected by FMD.
Fibromuscular dysplasia is an autosomal dominant disorder. It tends to occur between 14 and 50 years of age, but it has also been found in children younger than age 14.
Fibromuscular dysplasia is characterized by fibrous thickening of the intima
, or adventitia
of the renal artery
. Up to 75% of all patients with FMD will have disease in the renal arteries. The lesions cause narrowing of the artery lumen
. The second most common artery affected is the carotid
artery, which is found in the neck and supplies the brain with blood. Less commonly, FMD affects the arteries in the abdomen (supplying the liver
) and extremities (legs and arms). More than one artery may have evidence of FMD in 28% of people with this disease. All arteries should be checked if found.
Signs and Symptoms
As a result of renal artery stenosis, the kidney's afferent arteriolar
pressure falls. The renin-angiotensin system
is activated, causing fluid retention and hypertension. Symptoms of craniocervical involvement include headaches and lightheadedness, although patients are often asymptomatic. On physical examination, one may detect neurological symptoms secondary to a stroke, a bruit over an affected artery, and diminished distal pulses.
, and Angiotensin II receptor antagonists
are often initial treatments of fibromuscular dysplasia. Refractory cases are often treated by balloon angioplasty or stenting of the affected artery
Besides high blood pressure control
drugs and blood thinner
drugs may be used. Bypass surgery is a considered treatment and also vein replacement.
Ace Inhibitors are contraindicated in renal artery stenosis due to the risk of renal failure with inhibition of the Renin-Angiotensin-Aldosterone system to provide blood flow in the stenotic vessel.