Renal Artery Disease
Renal (or kidney) artery disease is a condition that develops when the arteries in the abdomen that supply the kidneys become narrowed, or blocked, by an accumulation of a fatty substance called plaque. As plaque builds up inside the artery walls, the arteries can become hardened and narrowed (a process called atherosclerosis). Atherosclerosis affects up to 35 percent of Americans, and can cause narrowing (also called stenosis) of any of the arteries throughout the body.
As atherosclerosis affects the whole body, people with renal artery narrowing often have other cardiovascular conditions such as carotid artery disease and heart disease. In renal artery disease, the narrowed arteries reduce blood flow to the kidneys, causing progressive kidney failure or difficult-to-control high blood pressure in a significant number of patients.
Risk Factors and Symptoms
Renal artery disease can also develop as a result of fibromuscular dysplasia (FMD). FMD is a condition in which abnormal cells cause narrowing throughout certain arteries, particularly those that supply the kidneys with blood. FMD can also affect the carotid arteries and arteries in the pelvis. This condition can affect anyone but is often seen in women between the ages of 20 and 40. Less commonly, injuries to the kidney can result in scarring, which can block the arteries to the kidney. With renal artery disease, patients can develop high blood pressure that is very difficult to control, and in extreme cases kidney failure.
Risk factors for renal artery disease include:
- Smoking - the number one risk factor for all cardiovascular diseases
- Family history of atherosclerosis, high blood pressure, diabetes, high cholesterol, advanced age, or obesity
- Sedentary lifestyle
Your doctors can use one or more of the following imaging tests to determine the location and the extent of the arterial stenosis:
- Duplex ultrasound
- Magnetic resonance angiography (MRA)
- CT scan
Patients whose symptoms are mild to moderate can often manage their disease by making lifestyle changes such as quitting smoking, getting regular exercise, and working with their doctors to take care of related conditions such as diabetes, high blood pressure, and high cholesterol. Doctors often use minimally invasive procedures such as balloon angioplasty and stenting to relieve the narrowing and improve blood supply to the kidneys. In severe cases, an abdominal bypass operation may be necessary to improve the blood flow to the kidneys. These treatment options are listed as follows:
Balloon angioplasty. During this procedure, your doctor places a tiny, soft plastic tube called a catheter into the artery, usually in the groin, and inject a dye that makes the blood vessels clearly visible on an x-ray image. Your doctor can also use a special catheter that has a small balloon at the end, which can be inflated and deflated. The deflated balloon catheter 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.
Stenting. In some cases, it may be necessary to place a stent. A stent is a small tube that holds open the artery at the site of the blockage. The stent is collapsed around a balloon when it is placed on the tip of the catheter and inserted into the body. Once the catheter reaches the blockage, the doctor expands the stent by inflating the balloon. The stent is left permanently in the artery to provide a reinforced channel through which blood can flow. Some stents (drug-eluting stents) are coated with medication that helps prevent the formation of scar tissue.
Arterial bypass surgery. If renal artery disease is severe, or if blockages develop in an artery that is difficult to reach with a catheter, kidney artery bypass surgery may be necessary to restore blood flow. In this treatment approach, doctors place a bypass graft made of synthetic material or a natural vein taken from another part of the body. During the procedure, the surgeon will make an incision to expose the diseased segment of the artery, and then attach one end of a bypass graft to a point above the blockage and the other end to a point below it. The blood supply is then diverted through the graft, around the blockage, to bypass the diseased section of the artery. The diseased artery is left in place.