By Pamela Mace, RN, & Jeffrey W. Olin, DO
What is Fibromuscular Dysplasia?
Fibromuscular dysplasia (FMD) is a noninflammatory vascular disease that most commonly affects the renal (kidney) arteries (1). While the carotid arteries are the second most common artery affected, FMD may affect any artery in the body (2, 3). FMD is often underdiagnosed and undertreated leading to the misconception that it is a rare disease. FMD causes narrowing (stenosis) and dilation (with possible aneurysm formation) (4) in the affected artery.
Up to 75 percent of all patients with FMD will have the disease in the renal arteries. The most common presentation of renal artery FMD is high blood pressure in a young woman or, less commonly, man. Renal FMD may also cause abnormal kidney function, flank pain and shrinkage (atrophy) of the kidney.
The second most common artery affected is the carotid artery, the main artery in the neck supplying blood to the brain. This is often detected when a doctor hears a noise in the patient’s neck (a bruit) when listening with a stethoscope. Patients may also complain of a swishing sound in the ears. Other symptoms include dizziness, temporary loss of vision, ringing in the ears, vertigo, neck pain, headaches, transient ischemic attack (blood supply to brain briefly interrupted). Other arteries less commonly, but also, affected include the arteries in the abdomen (supplying the liver, spleen and intestines) which may cause abdominal pain after eating and unintended weight loss. FMD in the extremities may cause exertional limb discomfort and rarely FMD may occur in the arteries of the heart causing a heart attack or chest pain. Nearly one-third of all patients with FMD have involvement of more than one artery (2).
What Causes FMD
The cause of FMD is not known, although genetic, hormonal and mechanical factors have all been suggested. FMD may be more than a single condition with more than one cause and investigation is underway to try and identify genetic factors that may cause FMD. Since FMD is more commonly seen in women than in men, some have suggested hormones may play a role in disease development.
How is FMD Diagnosed
There are a number of methods that can be used to detect FMD. These include computed tomographic angiography (CTA) and magnetic resonance angiography (MRA), ultrasound and catheter based angiography. In the most common form of FMD (medial fibroplasia), a characteristic “string of beads” appearance is seen in the affected artery. This appearance is due to changes in the cellular tissue of the artery wall that causes the arteries to alternatively become narrow and dilated. In medial fibroplasia, there are fine webs of tissue in the arteries causing the narrowing. A less common, but more aggressive form of FMD may cause an area of severe concentric narrowing of the blood vessel (intimal fibroplasia) or long smooth narrowing. Intimal fibroplasia is the most common form of FMD in children but may also occur in adults.
How is FMD Treated
There is no cure for FMD; however FMD can be adequately managed in most cases. The treatment used for FMD depends upon which arteries are affected and the presence and severity of the signs or symptoms. Medical therapy for renal FMD consists of blood pressure lowering medication to control blood pressure. It is recommended most patients take aspirin 81 mg daily which acts to prevent platelets from sticking together. Before starting any medication, patients should discuss treatment options with their physician.
Percutaneous transluminal angioplasty (PTA) is the preferred treatment for patients with FMD who require therapy due to narrowing of an artery. Indications for renal artery PTA include recent or rapid onset of high blood pressure and difficulty in controlling high blood pressure with medications. Often, the blood pressure can be cured with angioplasty, if performed properly. During angioplasty, a catheter is inserted into the affected artery and a small balloon is inflated to open the blood vessel in the area of narrowing. A recent study demonstrated improvement or cure in three-quarters of the patients undergoing PTA for renal artery FMD and these excellent results were maintained for up to five years in most patients (5). A metal stent is typically not recommended in FMD and should only be used if angioplasty alone was not successful or to treat a dissection (tear) of the artery (3). Surgical reconstruction is reserved with FMD and aneurysms or complex FMD within the kidney itself.
Prognosis
There are no specific studies on the long term prognosis and outcome of FMD. The causes, natural history, management and long-term outcome require further research. The International Registry for FMD is currently underway and will provide much needed information about this poorly understood condition.
How can I find out more about FMD
For more information on fibromuscular dysplasia please visit the Fibromuscular Dysplasia Society of America (FMDSA) at www.fmdsa.org.
Reference List
1. Sperati CJ, Aggarwal N, Arepally A, Atta MG. Fibromuscular dysplasia. Kidney Int 2008; Epub ahead of print.
2. Slovut DP, Olin JW. Fibromuscular dysplasia. N Engl J Med 2004; 350(18):1862-1871.
3. (Olin JW, Pierce M. Contemporary management of fibromuscular dysplasia. Curr Opin Cardiol 2008; 23(6):527-536.
4. Olin JW. Recognizing and managing fibromuscular dysplasia. Cleve Clin J Med 2007; 74(4):273-282.
5. Davies MG, Saad WE, Peden EK, Mohiuddin IT, Naoum JJ, Lumsden AB. The long-term outcomes of percutaneous therapy for renal artery fibromuscular dysplasia. J Vasc Surg 2008; 48(4):865-871.
Pam Mace, RN, is a registered nurse and President of the of Fibromuscular Dysplasia Society of America.
Jeffrey W. Olin, DO, is Professor of Medicine and Director of Vascular Medicine at the Zena and Michael A. Wiener Cardiovascular Institute and Marie-José and Henry R. Kravis Center for Cardiovascular Health Mount Sinai School of Medicine in New York.
This article originally appeared in the May 2009 issue of Kidney Beginnings: The Magazine.
Back
|
