What is renal stenting?

A small metal tubular structure called a stent is inserted into the renal artery that supplies essential blood flow to the kidneys. The stent acts as scaffolding, keeping the artery stretched open and maintaining adequate blood flow through the vessel after it is opened with a balloon.

When does a patient’s condition require renal artery stenting?

Plaque build-up (atherosclerosis) and sometimes other abnormalities of the renal artery may cause enough narrowing or blockage so that blood supply to the kidney is reduced and the risk of kidney damage becomes very high. Because the kidneys serve as a filter to remove waste products and excess fluids from blood, the kidneys receive almost one third of the blood flow from the heart. The kidneys also play a major role in regulating blood pressure. If left untreated, renal artery stenosis can lead to a form of high blood pressure called renovascular hypertension, poor functioning of the kidneys, and/or kidney failure.

What tests can determine a need for renal artery stenting?

A renal arterial duplex ultrasound is a noninvasive test that uses sound waves to create an image of the renal arteries and to measure the speed at which blood flows through them in order to detect any narrowing or obstruction in the renal arteries. It is useful as a screening test and for follow up studies.

Computed tomography angiography (CTA) is a type of CAT scan that uses x-ray beams taken from different angles around the patient to create pictures of cross-sections of the body. Contrast medium is injected into the veins at the time of the CT scan so that the arteries will also be visualized. Using computerized techniques, the scanner can be programmed to show pictures of only the arteries, which is a CT angiogram.

A Magnetic Resonance Angiogram (MRA) is a variant of an MRI study that uses radio waves and a magnetic field to take pictures of blood vessels. Unlike CTA and invasive angiography, MRA does not use x-rays or any form of radiation. MRA also uses a different type of contrast medium that does not have the same potential for side effects and complications. Not all patients can have MRA.

A nuclear kidney scan, a form of radionuclide imaging, tracks a small amount of nuclear tracer as it moves through the renal arteries. Images are recorded and blockages or narrowing in the renal artery may be detected, but the test is only an indirect assessment of arterial blockage.

A renal angiogram, or arteriogram is an invasive procedure involving insertion of a catheter, usually through a leg artery, up to the renal arteries where contrast medium is injected and X-ray pictures are taken to show the inside of the renal vessels.  A renal angiogram is the most accurate tests in the diagnosis of renal artery disease, and is used to pinpoint the location and severity of plaque build up and blockage.

How is renal artery stenting performed?

Renal stenting is a catheter- based procedure. The catheter acts as a guide to place the stent in the renal artery to open a narrowing or blockage.  The stent is deployed at the time the blockage in the artery is dilated with a balloon.  Stents come in a variety of strengths, sizes, and other properties. Stent selection for each procedure depends upon many factors, including the size of the artery, the location of the plaque build-up or blockage and the severity of arterial narrowing.

What should be expected after renal artery stenting?

Renal artery stents are exposed to blood flow and may cause clots to form until they become covered with tissue by the body. Medications are taken during this time, and possibly longer, to prevent thrombosis (formation of blood clots). Check your anticoagulant therapy section in this brochure to determine what medication your cardiologist has prescribed.

Sometimes new blockages develop in the renal arteries months or years later at a different site in a renal vessel.  Occasionally, renal stents re-narrow (restenosis). Because of the possibility of restenosis and / or new blockages, your cardiologist will want you to follow-up with a diagnostic testing schedule. Adhere to your testing and follow-up schedules below. Call your cardiologist’s office to schedule any tests that are not prescheduled. Follow-up is vital to early detection of re-narrowing or new disease of the renal arteries.

The usual recommendation for renal stent follow up is a diagnostic study at:

• Six weeks
• Six months
• One year
• Then Annually