WHAT IS: Renal Artery Angiogram and Stenting
Renal Artery Stenting (RAS) is performed to open blocked arteries caused by Renal Artery Stenosis and to restore arterial blood flow to the kidney without the need for open-vascular surgery. RAS is usually comprised of both angioplasty (PTA – percutaneous transluminal angiolplasty), followed by stent placement. It is performed in an outpatient setting (to treat a severe renal artery blockage).
A special catheter is inserted through the major artery in the leg or arm and advanced to the blocked renal artery. Through the catheter, a tiny wire is inserted into the artery and threaded across the blockage. Over this wire, a tiny balloon is advanced to the blockage. The balloon is inflated once the catheter has been placed into the narrowed area of the coronary artery. The inflation of the balloon compresses the fatty tissue in the artery and makes a larger opening inside the artery for improved blood flow.
What is stent placement?
In the past few years, many refinements have been developed in the RAS procedure. One common procedure used in RAS is stent placement. A stent is a tiny, expandable metal coil that is inserted into the newly-opened area of the artery to help keep the artery from narrowing or closing again.
Once the stent has been placed, tissue will begin to form over it within a few days after the procedure. The stent will be completely covered by tissue within a month to one year. It is necessary to take anti-platelet medications, such as aspirin or clopidogrel (Plavix™), which decreases the “stickiness” of platelets (a type of blood cells that clump together to form clots to stop bleeding), in order to prevent blood clots from forming inside the stent
Renal Artery Stenosis
Renal artery stenosis (RAS) is the narrowing of one or both arteries that carry blood to the two kidneys. “Renal” means “kidney” and “stenosis” means “narrowing.” RAS can cause high blood pressure and reduce kidney function. RAS is often overlooked as a cause of high blood pressure.
You are at greater risk of developing RAS if you smoke or are overweight. RAS is most common in men between the ages of 50 and 70, but women and younger adults can also have it. High cholesterol, diabetes, and a family history of cardiovascular disease are also risk factors for RAS. High blood pressure is both a cause and result of RAS.
What are the kidneys?
Your two kidneys are bean-shaped organs, each about the size of a fist. They are located just below the rib cage, one on each side of the spine. The arteries that carry blood to the kidneys—called the renal arteries—branch off directly from the abdominal aorta, the main vessel from the heart that supplies blood to most of the body’s organs.
Healthy kidneys filter out wastes and extra fluid from the blood that passes through them. Those wastes and extra fluid become urine, which flows from the kidneys to the bladder through tubes called ureters. Urine is stored in the bladder until released through urination.
What causes RAS?
In an overwhelming majority of cases, RAS is caused by atherosclerosis, hardening of the kidney arteries. Thus, RAS develops when a material called plaque builds up on the inner wall of one or both of the renal arteries. The plaque makes the artery wall hard and narrow. This narrowing reduces or cuts off the blood supply, possibly damaging the kidney. The damaged kidney is less efficient at removing wastes and extra fluid from the blood. This plaque is similar to plaques blocking the arteries supplying the heart, which cause heart attacks, and those blocking arteries supplying the brain, which cause strokes.
When the kidneys fail, wastes and extra fluid build up in the blood. This condition, called uremia, causes nausea, headaches, fatigue, and swelling in the legs and abdomen. With total kidney failure, you will need dialysis or a kidney transplant to stay alive.
What are the symptoms of RAS?
RAS can be silent, meaning you will not feel any symptoms, until it becomes severe.
The first sign of RAS may be high blood pressure that stays high even when you take blood pressure medicine. High blood pressure caused by RAS is called renovascular hypertension. Your doctor cannot diagnose RAS based on blood pressure alone because many conditions can cause your blood pressure to rise. If you develop high blood pressure suddenly and have no family history of high blood pressure, or if your blood pressure is difficult to control, your doctor might suspect RAS.
How is RAS diagnosed?
When blood flows through a narrow vessel, it makes a whooshing sound, called a bruit (BROO-ee). Your doctor may place a stethoscope on the front or the side of your abdomen to listen for this sound. The absence of this sound, however, by no means excludes the possibility of RAS.
For a more accurate diagnosis, your doctor may order an ultrasound or an angiogram to get a picture of the artery. An ultrasound uses harmless sound waves to create images of internal organs; it does not require intravenous injection or oral administration of any substances. An angiogram is a special kind of x ray in which a thin, flexible tube called a catheter is threaded through the large arteries, often from the groin, to the artery of interest—in this case, the renal artery. A special dye is injected through the catheter so the renal artery will show up clearer on the x ray. The advantage of angiograms is that they give a better picture and therefore more accurate diagnosis of RAS; the disadvantage is that this procedure is more invasive.
More recently, doctors have been using computerized tomography (CT) scans and magnetic resonance angiograms (MRA) to evaluate RAS. CT scans use multiple x-ray images combined by a computer to create a three-dimensional image of your internal organs. MRAs use moving magnets to create similar three-dimensional images. CT scans and MRAs are less invasive than conventional angiograms, but the results may not be as clear or accurate. Researchers are exploring ways to improve these imaging techniques and make them more reliable for evaluating RAS.
How is RAS treated?
Approaches to RAS are threefold:
- preventing RAS from getting worse
- treating high blood pressure that results from RAS
- relieving the blockage of the renal arteries
The first step in treating RAS is making lifestyle changes that promote healthy blood vessels in general. Exercising, controlling your weight, and choosing healthy foods will help keep your arteries clean and flexible. If you smoke, quitting is one of the best things you can do to save your kidneys and other organs.
Blood Pressure Medicines
RAS causes high blood pressure, which can damage the kidneys. Damaged kidneys, in turn, can make your blood pressure even higher. If left uncontrolled, this vicious cycle can lead to kidney failure and damage the heart and blood vessels throughout the body.
Controlling renovascular hypertension is often difficult but usually achievable. It may require two or more different kinds of blood pressure medicine. Blood pressure medicines work in different ways.
Sometimes, by combining two or more blood pressure medicines that work in different ways, you may be able to control your blood pressure and stop the progression of kidney failure. Each type of blood pressure medicine has its own potential side effects; therefore, the choice of medicine is best determined by you and your doctor.
In addition to blood pressure medicines, your doctor may prescribe a cholesterol lowering drug to prevent the plaques from forming in the arteries, and a blood-thinner, such as aspirin, to help the blood flow more easily through the arteries.
Risks of the Procedure: Possible risks associated with PVI include, but are not limited to, the following:
- allergic reactions
- medication reactions
- leg pain or discomfort
- damage to the blood vessel(s) into which a catheter is inserted which could require surgical repair
- there is small risk (under 1%) of the coronary artery becoming narrowed during the procedure, resulting in the need for immediate, emergent arterial bypass surgery.
- damage to the kidneys which could require dialysis
- heart rhythm disturbances
- myocardial infarction
- nerve injury
The risk of any one of these serious complications is less than 1%.
The amount of radiation used in fluoroscopy during a angioplasty or stent procedure is considered minimal; therefore, the risk for radiation exposure is very low.
If you are pregnant or suspect that you may be pregnant, you should notify your physician due to risk of injury to the fetus from a PVI. Radiation exposure during pregnancy may lead to birth defects. If you are lactating, or breastfeeding, you should notify your physician.
There is a risk for allergic reaction to the dye. Patients who are allergic to or sensitive to medications (ASPIRIN), contrast dye, iodine, or shellfish should notify their physician. Also, patients with kidney failure or other kidney problems should notify their physician.
Since this procedure requires you to take anti-platelet medications, please inform you physician if you currently have or have a history of bleeding problems. Please also tell your physician if have any surgical procedures planned in the near or distant future.
For some patients, having to lie still on the procedure table for the length of the procedure may cause some discomfort or pain.
There may be other risks depending upon your specific medical condition. Be sure to discuss any concerns with your physician prior to the procedure.
Before the Procedure: Your physician will explain the procedure to you and offer you the opportunity to ask any questions that you might have about the procedure.
You will be asked to sign a consent form that gives your permission to do the test. Read the form carefully and ask questions if something is not clear.
Notify your physician if you have ever had a reaction to any contrast dye, or if you are allergic to iodine, seafood, or aspirin.
Notify your physician if you are sensitive to or are allergic to any medications, latex, tape, and anesthetic agents (local and general).
You will need to fast for a certain period of time prior to the procedure. Your physician will notify you how long to fast, whether for a few hours or overnight.
If you are pregnant or suspect that you may be pregnant, you should notify your physician.
Notify your physician if you have any body piercings on your chest and/or abdomen.
Notify your physician of all medications (prescription and over-the-counter) and herbal supplements that you are taking.
Notify your physician if you have a history of bleeding disorders or if you are taking any anticoagulant (blood-thinning) medications, aspirin, or other medications that affect blood clotting.
Your physician may request a blood test prior to the procedure to determine how long it takes your blood to clot. Other blood tests may be done as well.
You may receive a sedative prior to the procedure to help you relax.
The area around the catheter insertion (groin area) may be shaved.
Based upon your medical condition, your physician may request other specific preparation.
During the Procedure
A PVI may be performed as part of your stay in a hospital. Procedures may vary depending on your condition and your physician’s practices.
Generally, a RAS follows this process:
- You will be asked to remove any jewelry or other objects that may interfere with the procedure. You may wear your dentures or hearing aid if you use either of these.
- You will be asked to remove clothing and will be given a gown to wear.
- You will be asked to empty your bladder prior to the procedure.
- An intravenous (IV) line will be started in your hand or arm prior to the procedure for injection of medication and to administer IV fluids, if needed.
- You will be placed in a supine (on your back) position on the procedure table.
- You will be connected to an ECG monitor that records the electrical activity of the heart and monitors the heart during the procedure using small, adhesive electrodes. Your vital signs (heart rate, blood pressure, breathing rate, and oxygenation level) will be monitored during the procedure.
- There will be several monitor screens in the room, showing your vital signs, the images of the catheter being moved through the body into the heart, and the structures of the heart as the dye is injected.
- You will receive a sedative medication in your IV before the procedure to help you relax.
Your pulses below the insertion site will be checked and marked so that the circulation to the limb below the site can be checked after the procedure.
- A local anesthetic will be injected into the skin at the insertion site. You may feel some stinging at the site for a few seconds after the local anesthetic is injected.
- Once the local anesthetic has taken effect, a sheath, or introducer, will be inserted into the blood vessel. This is a plastic tube through which the catheter will be inserted into the blood vessel and advanced to the blocked artery.
- The angioplasty catheter will be inserted through the sheath into the blood vessel. The physician will advance the catheter through the aorta into the artery. Fluoroscopy will be used to assist in advancing the catheter to the artery.
- The catheter will be advanced to the blocked artery. Once the catheter is in place, contrast dye will be injected through the catheter into your arteries in order to see the narrowed area(s). You may feel some effects when the contrast dye is injected into the IV line. These effects include a flushing sensation, a salty or metallic taste in the mouth, and/or a brief headache. These effects usually last for a few moments.
- You should notify the physician if you feel any breathing difficulties, sweating, numbness, itching, nausea and/or vomiting, chills, or heart palpitations.
- After the contrast dye is injected, a series of rapid, sequential x-ray images of the heart and coronary arteries will be made. You may be instructed to take in a deep breath and hold it for a few seconds during this time.
- When the physician locates the narrowed artery, the interventional wire will be advanced to that location and the balloon will be inflated to open the artery. It is possible to experience some pain or discomfort at this point as a result of blood flow being temporarily blocked by the inflated balloon. Any discomfort or pain should go away when the balloon is deflated. However, if you notice any continued discomfort or pain, such as leg, back pain, arm pain, shortness of breath, or breathing difficulty, tell your physician immediately.
- The physician may inflate and deflate the balloon several times. The decision may be made at this point to insert a stent in order to maintain the artery's opening. In some cases, the stent may be inserted into the artery before the balloon is inflated. The inflation of the balloon will open the artery and fully expand the stent.
- The physician will take measurements after the artery has been opened. Once it has been determined that the artery is opened sufficiently, the angioplasty catheter will be removed.
- The insertion site may be closed with a closure device that uses collagen to seal the opening in the artery, by the use of sutures, or by applying manual pressure over the area to keep the blood vessel from bleeding. Your physician will determine which method is appropriate for your condition.
- If a closure device is used, a sterile dressing will be applied to the site. If manual pressure is used, the physician (or an assistant) will hold pressure on the insertion site so that a clot will form. Once the bleeding has stopped, a very tight bandage will be placed on the site. A small sandbag or other type of weight may be placed on top of the bandage for additional pressure on the site, especially if the site is in the groin.
- Your physician may decide not to remove the sheath, or introducer from the insertion site for approximately four to six hours, in order to allow the effects of blood-thinning medication given during the procedure to wear off. You will need to lie flat during this time. If you become uncomfortable in this position, your nurse may give you medication to make you more comfortable.
- You will be assisted to slide from the table onto a stretcher so that you can be taken to the recovery area. NOTE: If the insertion was in the groin, you will not be allowed to bend your leg for several hours. To help you remember to keep your leg straight, the knee of the affected leg may be covered with a sheet and the ends tucked under the mattress on both sides of the bed to form a type of loose restraint.
- If the insertion site was in the arm, your arm will be kept elevated on pillows and kept straight by placing your arm in an arm guard (a plastic arm board designed to immobilize the elbow joint). In addition, a plastic band (works like a belt around the waist) may be secured around the arm near the insertion site. The band will be loosened at given intervals and then removed at the appropriate time determined by your physician.
After the Procedure - In the hospital:
After the procedure, you may be taken to the recovery room for observation or returned to your hospital room. You will remain flat in bed for several hours after the procedure. A nurse will monitor your vital signs, the insertion site, and circulation/sensation in the affected leg or arm.
You should immediately inform your nurse if you feel any chest pain or tightness, or any other pain, as well as any feelings of warmth, bleeding, or pain at the insertion site in your leg or arm.
Bedrest may vary from two to six hours depending on your specific condition. If your physician placed a closure device, your bedrest may be of shorter duration.
In some cases, the sheath or introducer may be left in the insertion site. If so, the period of bedrest will be prolonged until the sheath is removed. After the sheath is removed, you may be given a light meal.
You may feel the urge to urinate frequently because of the effects of the contrast dye and increased fluids. You will need to use a bedpan or urinal while on bedrest so that your affected leg or arm will not be bent.
After the specified period of bed rest has been completed, you may get out of bed. The nurse will assist you the first time you get up, and will check your blood pressure while you are lying in bed, sitting, and standing. You should move slowly when getting up from the bed to avoid any dizziness from the long period of bedrest.
You may be given pain medication for pain or discomfort related to the insertion site or having to lie flat and still for a prolonged period.
You will be encouraged to drink water and other fluids to help flush the contrast dye from your body.
You may resume your usual diet after the procedure, unless your physician decides otherwise.
After the procedure - At home:
Once at home, you should monitor the insertion site for bleeding, unusual pain, swelling, and abnormal discoloration or temperature change at or near the insertion site. A small bruise is normal. If you notice a constant or large amount of blood at the site that cannot be contained with a small dressing, notify your physician.
If your physician used a closure device for your insertion site, you will be given specific information regarding the type of closure device that was used and how to take care of the insertion site. There will be a small knot, or lump, under the skin, where the insertion site was. This is normal. The knot should gradually disappear over a few weeks.
It will be important to keep the insertion site clean and dry. Your physician will give you specific bathing instructions.
You may be advised not to participate in any strenuous activities. Your physician will instruct you about when you can return to work and resume normal activities.
Notify your physician to report any of the following:
- fever and/or chills
- increased pain, redness, swelling, or bleeding or other drainage from the insertion site
- coolness, numbness and/or tingling, or other changes in the affected extremity
- chest pain/pressure, nausea and/or vomiting, profuse sweating, dizziness, and/or fainting
Your physician may give you additional or alternate instructions after the procedure, depending on your particular situation.