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The arteries that carry the blood to the kidneys are called renal arteries.

The kidneys are one of two organs (the other being the liver) that function as a filter to remove waste materials and excess fluids from the blood, excrete urine and help regulate the water, electrolytes (salts), and the pH (acidity) of the blood.The kidneys receive almost a third of the body’s blood flow. The kidneys also play a major role in regulating blood pressure.

What is renal artery disease?

Renal artery disease is artery disease that occurs in the blood vessels leading to the kidneys. As one ages, fatty deposits and/or calcium (sometimes referred to as plaque) builds up on the inside of our arteries. This disease process is called atherosclerosis.

Atherosclerosis is a progressive disease that involves the hardening and narrowing of the arteries due to this buildup of plaque. It can progress from causing a narrowing of the artery, called artery stenosis, to a total blockage, or total occlusion in which there is no blood flow) of the artery.

When the narrowing in the renal artery is significant, the kidney incorrectly senses that the blood pressure is too low. It signals the body to increase the blood pressure, resulting in high blood pressure called hypertension. It’s a vicious circle, because this type of high blood pressure can accelerate the progression of atherosclerosis throughout the body. This increases the strain on the heart.

When blood flow from the renal artery to the kidney is restricted, it can also result in a reduced ability of the kidneys to remove the waste and fluids from the body. This is called renal insufficiency. Renal artery stenosis can ultimately lead to kidney failure.

What are the risk factors for renal disease?

A history of your symptoms and your risk factors can help your physician to diagnose renal disease. Risk factors include:

  • Being overweight
  • Lack of regular exercise
  • Eating a high-fat diet
  • Uncontrolled diabetes
  • Smoking
  • High cholesterol
  • High blood pressure
  • Family history of peripheral artery disease

While you can’t control risk factors such as family history, you can control some of the risk factors. You can stop smoking, get regular exercise, eat a low-fat diet, lose weight, work with your doctor to control diabetes, high cholesterol, high blood pressure and to find ways to reduce your stress or anger levels.

How is renal artery disease diagnosed?

Your symptoms and your risk factors will be considered when making a diagnosis. Tests may include:

  • A renal artery duplex ultrasound scan – This is a non-invasive test using sound waves to create images of your renal arteries, as well as measure the speed at which flows through the arteries.
  • A CTA (computed tomography arteriography) scan- This scan uses X-rays takes from various angles to create pictures of cross sections of your body. When contrast dye is used, the arteries can be visualized. These pictures, while not as detailed as a renal arteriogram,, may be sufficient to make a diagnosis and only require an IV placed in the arm.
  • An MRA (magnetic resonance angiogram) scan – This is like an MRI (Magnetic Resonance Imaging scan). However, it uses radio waves (instead of X-rays or any form of radiation) and a magnetic field to take pictures of the blood vessels to take successive pictures of the blood vessels. A contrast fluid is sometimes used; however it is different in that it is different than that used for the renal arteriogram and CTA. The advantage is that is does not have the potential negative side effects on the kidneys. However. like the CTA, MRA uses computer techniques to make the blood vessels more visible.
  • Blood tests – Certain blood tests can identify substances in the blood either produced by the kidneys or are increasing when the kidneys are wot working properly.
  • A renal arteriogram, also called an angiogram – This 20-40 minute procedure is performed in a special room in the hospital called a catheterization laboratory (cath lab) by an Interventional Radiologist and cath lab staff. This exam, involving X-rays, serves to identify narrowed or blocked renal arteries. After the procedure is explained to you and consent forms are signed, an small intravenous (IV) tube will be inserted into your arm, allowing IV fluids and medications to be administered. Through the IV, a mild sedative is given so you can relax for the procedure. Small sticky patches (electrodes) are on your chest to monitor your heart rate and rhythm. The area where a catheter will be inserted (either your groin or your arm) will be shaved and washed, and numbing medication will be applied as a local, topical anesthetic. Your body will be draped with sterile sheets. Next, a hollow tube will be placed at the point of access (groin or arm) through which your doctor can advance or remove guide wires and catheters to the arteries leading to your kidneys. A special X-ray contract dye will be pushed through the tube to allow your doctor to see and record images of the arteries leading to your kidney on an X-ray monitor. Once the doctor has finished the angiogram and other treatments or procedures (if any) are complete, you will go to a recovery area for monitoring. Four to six hours following the procedure, you will be asked to lie flat and not bend your leg or arm, depending on which approach your doctor used to insert the catheters. A vascular closure device may be used to seal the puncture site in your groin or arm.

What are possible treatments for renal artery disease?

The goal of treatment is to increase the flow of blood to the kidneys. It is best to control those factors, as outlined above, that you can. Lifestyle changes will increase your chances of long-term success with any of the treatments below that may be considered. In a nutshell, possible treatments may include drug therapy, surgical procedures, and balloon angioplasty, sometimes with stenting.

  • Drug therapy – Your doctor may prescribe drugs to dilate (or expand) the arteries to increase the blood flow to your kidneys. If you have high blood pressure, drugs to lower blood pressure may be prescribed.
  • Surgical procedures – These two procedures — renal artery endarterectomy or renal artery bypass– are both surgical procedures in which patients may be hospitalized for at least a week.
    • Renal artery endarterectomy – In this surgical procedure, the surgeon exposes the renal artery through an incision. The plaque is physically removed.
    • Renal artery bypass, is a similar procedure as the renal artery endarterectomy except that a bypass is made around the blocked artery rather than removing the plaque from the artery. A healthy segment of vein or artery from another part of the body is used to create a bypass (detour) so blood can flow around the clogged area.
  • Balloon Angioplasty – known as Percutaneous Translumenal Angioplasty – PTA – This procedure is similar to the renal arteriogram procedure described above. A catheter with a small balloon on the tip is directed to the area of plaque buildup in the renal artery. The balloon is then inflated to push the plaque against the artery wall to create a larger arterial opening. The improves the blood flow through the artery or, in other words, widens the “artery lumen.” The balloon is then deflates, after which the catheter with balloon attached is withdrawn from the body.
  • Stenting – In some cases, it is determined that the result of the balloon angioplasty alone will not provide sufficient blood flow through the arteries. In such instances, the interventional radiologist may place a stent (an expandable wire-mesh tube) in the artery to keep it from closing again (a condition called restenosis). The stent is a mesh-like tubular metal scaffold placed on a specially designed balloon catheter and then delivered to the diseased area in the same fashion as the PTA balloon catheter. For some patients, stenting is contraindicated because 1) they cannot take platelet inhibitors (anti-platelet) and-or anticoagulation therapy that may be needed, or 2) their renal artery disease in a location that prevents complete inflation of an angioplasty balloon.

What happens after the stent procedure?

Note that you may need to take drugs before and after the procedure. Aspirin and platelet inhibitors are the most commonly prescribed drugs. It is important that you take all medications as prescribed.

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