What are renovascular conditions?
Renovascular conditions affect the blood vessels of your kidneys. When the blood flow is normal through your kidneys, your kidneys filter wastes into your urine. Your kidneys also help control blood pressure by making a hormone called renin. When your kidney blood vessels narrow, your kidney is less able to do its work. Renal artery stenosis (another name for narrowing of the kidney arteries) may cause high blood pressure and may eventually lead to kidney failure.
What are the symptoms?
Renovascular conditions develop slowly and worsen over time. You may not notice any symptoms. If you have high blood pressure, the first sign that you may have renal artery stenosis is that your blood pressure may become higher or the medications that you take to control your blood pressure may not be as effective. Other signs of renal artery stenosis are a whooshing sound in your abdomen that your physician hears through a stethoscope, decreased kidney function, congestive heart failure or, eventually, a small shrunken kidney.
What causes renovascular conditions?
Hardening of the arteries is the most common cause of renal artery stenosis. Your arteries are normally smooth and unobstructed on the inside but, as you age, a substance called plaque can build up in the walls of your arteries. Cholesterol, calcium, and fibrous tissue make up this plaque. As more plaque builds up, your arteries can narrow and stiffen. This is the process of atherosclerosis, or hardening of the arteries. Eventually, enough plaque may build up to interfere with blood flow in your renal arteries. Smoking, obesity, advanced age, high cholesterol, diabetes, and a family history of cardiovascular disease are factors that may increase your chances for developing atherosclerosis.
What tests will I need?
Your physician may recommend one or more of the following tests to determine if you have renal artery stenosis:
Ultrasound: allows your physician to see your blood vessels and organs using high-frequency sound waves. Using ultrasound, your physician can locate narrow areas inside your arteries and also determine the size of your kidney;
Angiography: more invasive than ultrasound; can locate a narrowing or blockage, can measure blood flow, and can be used to sample blood for testing. In this test, your physician injects contrast dye into your vessels through a small catheter and then takes x-rays. This test finds the location and pattern of blockages in your kidney blood vessels. The dye itself is later eliminated through your kidneys and it sometimes can affect their function;
Spiral computed tomography (CT) scan: creates detailed three-dimensional images from x-rays of slices of your body. This study also sometimes uses contrast dye;
Magnetic resonance angiography (MRA): uses magnetic fields and radio waves to produce three-dimensional images of your arteries. This study also sometimes uses contrast dye.
How are renovascular conditions treated?
Medication: If your physician diagnoses renal artery stenosis, he or she may prescribe blood pressure medications.
Angioplasty and stenting: If your renal artery is partially or completely blocked, your physician may recommend a procedure called angioplasty and stenting. To perform this procedure, a catheter is inserted through a small puncture site and guided under x-ray to your renal artery. The catheter carries a tiny balloon that can be inflated at the site of narrowing, thereby widening this segment of vessel. Next, your physician may insert a tiny metal-mesh tube called a stent in the artery to hold it open. This procedure, when needed, is often performed at the time of angiography.
Surgery: Two surgical procedures that your physician may use to treat renal artery stenosis are endarterectomy and surgical bypass. In a renal endarterectomy, a vascular surgeon removes the plaque from the inner lining of your renal artery. This procedure leaves a smooth, wide-open artery. Bypass surgery creates a detour around the narrowed or blocked sections of your renal artery. To create this bypass, a vascular surgeon connects a bypass graft above and below the area that is blocked. This creates a new path for your blood to flow to your kidneys. The choice of the procedure that is best for your situation depends upon the extent and location of the blockages. Your vascular surgeon will advise you regarding which procedure is best for your particular situation.
What can I do to stay healthy?
Lifestyle changes are important to help reduce problems associated with renovascular conditions. Your physician will encourage you to change any factors that put you at greater risk for problems. Some of these changes may include:
- Quitting smoking;
- Maintaining your ideal body weight;
- Controlling your cholesterol and lipid levels;
- Controlling your blood pressure;
- Exercising regularly; and
- Eating a low-fat, low-protein, low-sodium, high-fiber diet.