Renal vascular disease, also known as renal artery stenosis, is a form of arterial disease. The renal artery delivers blood to the kidneys, the organ responsible for filtering waste from the body.
Like other arteries, the renal arteries can become obstructed with a build-up of plaque, which causes decreased blood flow to the kidneys. When this happens, the kidney reacts to this lower blood flow as if the body's overall blood pressure is low and responds by releasing an enzyme called renin into the bloodstream.
Renin causes smaller vessels to constrict and the body to retain sodium, which is normally lost in urine. These events cause blood pressure to rise, resulting in hypertension (high blood pressure). As these blockages worsen, the kidney may have difficulty in clearing the body's waste products and kidney failure can occur.
Causes of Renal Vascular Disease
The most common cause of renal artery blockages is arteriosclerosis (the thickening and hardening of artery walls) with cholesterol and plaque build-up. This is similar to what is seen in the coronary arteries of the heart, the carotid arteries to the brain and the leg vessels. Men are affected with this condition twice as often as women, with 55 the average age at diagnosis. Other causes of renal vascular disease include:
- Fibromuscular dysplasia (FMD), an abnormal growth on the inside of the renal artery that typically affects middle-aged women, but has been found in men and people of all ages.
- Renal artery aneurysms (abnormal bulging of a part of the renal artery) can often twist or compress a nearby renal artery, causing it to become narrowed.
Symptoms of renal artery disease include:
High blood pressure that is difficult to treat with medicines, especially in women under age 45.
Worsening of the kidney's function to clear the body's waste products, determined by blood samples, especially when high blood pressure medicines are needed, in particular ACE inhibitors like lisinopril.
Unusual nosebleeds, ringing in the ears (tinitus) and headaches early in the morning involving the back of the head — if hypertension is severe. If untreated, high blood pressure caused by the kidneys, or renovascular hypertension, may lead to a number of serious cardiovascular and kidney problems, including:
- Thickening of the heart muscle (hypertrophy)
- Worsening of arteriosclerosis of all the body's arteries
- Renal failure requiring dialysis
Diagnosis is typically made through an abdominal ultrasound scan or direct imaging of the artery. Imaging tests include CT scan, magnetic resonance angiography (MRA) or an arteriography, which can be used to determine the location and the extent of the arterial stenosis.
Endarterectomy: Involves the surgical removal of plaque build-up on the inner lining of the artery.
Bypass Grafting: Redirects blood flow around an area of blockage. The procedure creates an alternate channel for blood flow, bypassing an obstructed or damaged vessel. The graft may come from a healthy section of the patient's own vein, or from a synthetic material such as Dacron™.
In the case of aneurysms, the aneurysmal vessel may need to be removed through surgery and the affected artery repaired. In rare cases, the artery cannot be repaired and the kidney may need to be removed.
Angioplasty and Stenting: A catheter with a small balloon at the end is inserted through an artery in the groin and guided to the narrowed segment of the artery. When the catheter reaches the blockage, the balloon is inflated to widen the narrowed artery (known as balloon angioplasty).
In some cases, it may be necessary to place a stent (a wire-mesh tube that expands to hold the artery open). The stent is left permanently in the artery to provide a reinforced channel for blood flow.
Renal Vascular Disease Treatment at the University of Michigan
The University of Michigan has been a leader in the treatment of renal vascular disease since the 1960s. This breadth of experience has led the U-M Frankel Cardiovascular Center to become an internationally recognized referral center for the care of this complex condition, attracting patients from all over the globe.
Treatment is focused around a multidisciplinary approach and includes specialists from nephrology, interventional radiology, intensive care and vascular surgery. This means multiple specialists can be seen in a single visit and treatment strategies are a coordinated effort between every physician involved in the patient’s care.
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