Renal Artery Stenosis
Renal artery stenosis (RAS) is the narrowing of one or both of the renal arteries, the blood vessels that carry blood to the kidneys from the aorta. RAS often causes high blood pressure and reduced kidney function, but many times it has no symptoms until it becomes severe. Most cases of RAS are caused by a condition called "atherosclerosis," the clogging, narrowing and hardening of the renal arteries. RAS develops when plaque builds up on the inner wall of the renal arteries, causing them to harden and narrow. RAS can also be caused by fibromuscular dysplasia, an abnormal growth of tissue within the wall of the artery, which also causes the blood vessels to narrow.
Symptoms of Renal Artery Stenosis
In addition to hypertension (high blood pressure), people with RAS may have reduced kidney function, which can cause the following symptoms:
- Edema (swelling) of the hands or feet
- Increase or decrease in urination
- Muscle cramps
- Nausea
- Vomiting
- Weight loss
- Numbness
- Darkened skin
RAS may also cause symptoms of hypertension; they include headaches, dizziness and fatigue. Hypertension caused by renal artery stenosis is commonly referred to as "renal vascular hypertension."
Diagnosis of Renal Artery Stenosis
RAS is diagnosed through a physical examination and a review of symptoms. Blood and urine tests may be performed to check cholesterol and creatinine levels, and evaluate kidney function. Additional diagnostic tests include the following:
- Ultrasound
- Catheter angiogram
- MRI scan
- CT scan
- Magnetic resonance arteriogram (MRA)
RAS may be discovered when a person is being tested for other conditions, such as heart problems. RAS may be detected during a coronary angiogram, which is a test that is used to evaluate blood flow through the heart.
Treatment of Renal Artery Stenosis
RAS may initially be treated with conservative methods designed to lower blood pressure, and relieve the narrowing in the renal arteries. These methods include lifestyle changes such as stopping smoking, eating a healthful diet and exercising. Medication to lower cholesterol and control blood pressure may also be prescribed. If conservative methods are not effective, surgical treatment, including those below, may be recommended:
- Renal artery bypass
- Renal angioplasty and stenting
- Renal endarterectomy
Left untreated, RAS can lead to serious conditions that include chronic kidney disease, coronary artery disease, peripheral vascular disease and stroke.