Angioplasty and Vascular Stenting

Transcription

1 Angioplasty and Vascular Stenting

2 What Are Angioplasty And Vascular Stenting? Angioplasty is a way of opening a narrowed or closed blood vessel without having to do major surgery. A catheter with a tiny balloon at its tip is inserted into the vessel usually one of the coronary arteries supplying the heart wall or a major artery bringing blood to an arm or leg. After advancing the catheter until its tip is at the site of blockage, the balloon is inflated and then deflated and removed. The narrowing or blockage most often is caused by arteriosclerosis, or hardening of the arteries, when fatty plaques form on the inner wall of the artery and become larger, gradually cutting down on free blood flow. Expanding the balloon stretches the arterial wall and disrupts the fatty plaques, helping to restore blood flow. Between 70 percent and 90 percent of angioplasty procedures use a stent, a hollow thin-walled wire mesh tube, to keep the vessel open after widening it. Otherwise, because arteriosclerosis is an ongoing disease, more plaques might form and again limit blood flow. The stent is placed onto the balloon and pressed firmly against the artery wall when inflating it. The balloon then is deflated, leaving the stent in place to act as a scaffold. What Are Some Common Uses Of The Procedure? Arteries carry blood and oxygen throughout the body. When a major artery is narrowed or blocked, the tissue it supplies does not get enough oxygen. If this happens in a coronary artery, chest pain or angina is the usual result. If in the legs, you may have pain when walking or, in time, even when at rest. A blocked artery to one or both kidneys may cause high blood pressure. If angioplasty succeeds in opening up the artery, more oxygen will get to the tissues and relieve the symptoms. If you have any of these conditions, your physician may want to consult an Interventional Radiologist to advise you on the best form of treatment. Some blockages are best treated by surgery, and some by angioplasty. The most common uses of angioplasty/stenting are: To open a narrowed or blocked coronary artery in patients suffering severe angina, which causes chest pain upon physical effort because part of the heart wall is not getting enough blood. Angioplasty often is used as an alternative to coronary artery bypass surgery, a very major undertaking. It may be done in hope of preventing a heart attack, or afterwards with the goal of preventing another attack. To open up a blocked artery in the pelvis, leg or arm of patients with peripheral arterial disease, also caused by arteriosclerosis. The most common site of angioplasty in these patients is the iliac arteries of the pelvis. Insufficient blood can keep the leg muscles from working properly and make it very painful to walk. Those affected may in time

3 become chair-bound, but angioplasty/stenting can restore their ability to walk. This is especially important for older patients. To control the blood pressure in patients with renal hypertension when disease has narrowed one or both arteries supplying blood to the kidneys. To keep blood vessel grafts open in patients with kidney failure who have regular hemodialysis to prevent waste products from building up in the blood. Most of these patients have a graft constructed between an artery and vein in the arm so that blood can easily be withdrawn and replaced during dialysis. To maintain vital blood flow to the brain by keeping open the carotid artery, the major route of blood and oxygen to the brain. Angioplasty is most helpful to patients who are not good candidates for surgery. How Should I Prepare For The Procedure? Blood tests are routinely ordered; you may have blood drawn at the hospital or a nearby clinic. You may be instructed to temporarily stop taking certain medications such as those that thin the blood. If you have diabetes it may be necessary to alter your insulin dose on the day of angioplasty. Make sure that the Interventional Radiologist knows if you have any allergies so that special precautions can be taken. You will be asked not to eat solid foods after midnight, but may take clear liquids. Smoking is to be avoided the day before the procedure. Shortly before starting the procedure, the area where the catheter is to be inserted in the groin or arm will be shaved and washed with antibacterial soap to prevent infection. In addition, you will have a tube placed into a vein in the arm or hand to receive fluids and medicines as needed. The intravenous (IV) line is used to give a sedative to help you relax and may possibly make you drowsy, and an analgesic for any discomfort you may have. A catheter to empty your bladder during the procedure may be used. What Does The Equipment Look Like? Angioplasty, and stent placement when done, are monitored as they take place using high-resolution angiography equipment. Once in a while a different imaging procedure, ultrasonography, is performed in addition to angiography.

4 The equipment includes a balloon catheter, (a small, thin angioplasty catheter with a balloon at its tip) and, in some cases, a wire mesh stent that is collapsed when passed into the artery. Stents come in varying sizes to match the size of the diseased artery. How Does The Procedure Work? Angioplasty uses an inflatable balloon that is passed to the target vessel and inflated. When plaque is narrowing the artery and limiting the amount of blood that can get through, the inflated balloon will press against the side of the artery and stretch the artery wall. The result is that the vessel is restored to its initial size and thus allows more blood and oxygen to pass to the body tissues it normally supplies. Occasionally, the plaque will not remain against the inner lining of the artery but goes back to its former position after the balloon is deflated. Another possibility is that a small amount of plaque may continue to block the flow of blood. In these cases the Interventional Radiologist may place a stent that is expanded at the site of plaque. The muscle tissue in the vessel wall holds the stent in place. In time, a layer of cells forms over the stent, which in effect becomes part of the vessel. In some cases the size of the diseased artery and the site of blockage make a stent especially useful. A stent may be placed to keep an artery open if the inflated balloon has torn or is damaged. How Is The Procedure Performed? If the Interventional Radiologist orders sedation and an analgesic it will be given. Then a local anesthetic is injected into the skin where the catheter is to be inserted, usually in the groin. A very small incision is made at this site, and a needle is placed in the femoral artery in the groin. Next, a thin guidewire is placed through the needle and the needle is exchanged over the guidewire for a catheter that is then advanced toward the blocked artery. Occasionally access is gained instead through a large artery in the upper arm. The catheter is guided into the diseased segment of artery while being monitored on a TV screen that shows the artery and the catheter. A small amount of contrast material is injected to show the exact location of the narrowing. The balloon-tip catheter, which is thinner, is then inserted through the guide catheter. When its tip reaches the narrowed part of the artery, the balloon is inflated for about 30 seconds and then deflated. This is repeated several times to widen the artery. Finally the balloon-tip catheter is removed and angiography is repeated to make sure that blood flow has improved. This entire process usually takes between one to two hours.

5 Depending on the result of angioplasty, the site of narrowing, and the physician's judgment, one of two types of stents may be placed. One type is collapsed until very small in diameter and placed over a balloon-tip catheter. Inflating the balloon expands the stent, which then locks in place to keep the artery open. The other type is secured to a catheter by a sheath and self-expands when the sheath is removed. Stent placement may be combined with angioplasty or it may serve as an alternative procedure. What Will I Experience During The Procedure? When you receive a sedative and analgesic through the IV line at the outset, you will feel relaxed and sleepy but probably will stay awake throughout the procedure. There should be no pain when the catheter first is inserted into the groin artery, but you may notice slight pressure. You may feel pain briefly in the part of your body closest to the site of angioplasty when the balloon is inflated. This could be chest pain for coronary angioplasty, back pain for renal angioplasty, and buttock pain when iliac angioplasty is performed. After removing the catheter, pressure will be held on the site with a disk or by a staff member holding direct pressure. A closure device may also be used to prevent bleeding. You will have to remain on your back. Avoid moving your leg or groin for about one to six hours. Most patients will be able to walk about one to six hours after angioplasty. Some patients return home the same day, but most stay in hospital over night. On returning home you should take it easy, avoid driving for 24 hours, and drink plenty of fluids. You should avoid strenuous exercise for at least two days. It is best not to take a hot bath or shower for the first 12 hours, and to avoid smoking for 24 hours or longer. If bleeding begins where the catheter was inserted, you should lie down, apply pressure to the site, and have someone call your physician right away. Any change in color or a warm feeling in this area are also signs that something is wrong, as is pain in the area where the balloon was inflated. Who Interprets The Results And How Do I Get Them? The Interventional Radiologist judges the technical results of angioplasty or stent placement by comparing the pre- and post-procedure angiograms. If any narrowing remains, it should not exceed 30 percent of the normal vessel diameter. The patient can be told of the technical result as soon as the procedure is completed, though it is best to wait until the sedative has worn off. The clinical outcome may take longer to gauge. In the case of angioplasty of the arteries to the kidneys, clinical benefit should be evident in one to four weeks as a fall in blood pressure or the ability to reduce medication to control the pressure.

6 What Are The Benefits vs. Risks? Benefits Angioplasty, with or without stenting, is much less invasive than open surgery, which in the case of a coronary artery block means a bypass operation. When angioplasty succeeds, major surgery and use of a heart-lung machine are avoided. Overall cost is much less, and the hospital stay is a day or two rather than weeks. Angioplasty and stent placement can be done using only local anesthesia; you will not require a general anesthetic. No surgical incision is needed only a small nick in the skin that does not have to be stitched closed. You can return to your normal activities shortly after the procedure. Unlike bypass surgery, it is not necessary to remove pieces of blood vessels from another part of the body. Although the results may not be as lasting as those of bypass surgery, angioplasty can restore blood flow to vital tissues and relieve symptoms for some time. Even after bypass surgery, some of the new blood vessels occasionally become blocked. Risks You may have an allergic reaction to the contrast material injected for angiography. The risk of this happening is greater in patients with kidney disease, diabetes or asthma and those who have had a previous reaction to x-ray contrast material. Heavy bleeding from the catheter insertion site may call for special medication or blood transfusion. There is a risk of stroke when both angioplasty is performed and a stent is placed on the carotid artery. This is because a blood clot may form and travel to small brain vessels, where it stops blood flow to brain tissue that requires a steady oxygen supply.

7 What Are The Limitations Of Angioplasty And Vascular Stenting? Whenever angioplasty is attempted, a surgical team must be available to operate immediately if necessary. Regardless of what artery is blocked, angioplasty does not reverse the underlying disease arteriosclerosis. The procedure may have to be repeated if the same artery or another one becomes blocked. Only about half of patients with renal hypertension caused by arteriosclerosis have their blood pressure controlled by angioplasty. By the time the procedure is done, many of these patient s have disease in small arteries within the kidneys that cannot benefit from angioplasty. Angioplasty/stenting for arterial disease in the pelvis and legs is less successful when there are narrowings at more than one level; when small vessels have to be dilated; and when not enough blood gets through the treated segment of artery. Either recurrent narrowing at the site of treatment or progressive arteriosclerosis in an untreated artery may produce symptoms. Any patient with this disease, no matter which arteries are affected, stands to benefit from eating a proper diet, getting regular exercise, and controlling blood cholesterol. Placing a stent in the carotid artery that supplies blood to the brain remains controversial because open surgery has proven to be effective and safe. It certainly is helpful to patients who cannot safely undergo surgery. Before long it may be possible to use a filter device during stent placement that will keep clots from passing to the brain, thereby lowering the risk of stroke. What Is An Interventional Radiologist? Interventional Radiologists are physicians who specialize in minimally invasive, targeted treatments performed using imaging guidance. They use their expertise in reading X-rays, ultrasound, MRI and other diagnostic imaging equipment to guide tiny instruments such as catheters, through blood vessels or through the skin to treat diseases without surgery. Interventional Radiologists are board-certified and fellowship trained in nonsurgical invasive interventions using imaging guidance. The American Board of Medical Specialties certifies their specialized training. Your Interventional Radiologist will work closely with your primary caregiver or other physicians to be sure you receive the best possible care.

8 Your (test/procedure) is scheduled on (date) at (time), (location) Helpful tips: Wear comfortable clothes. Bring someone with you to drive you home after the procedure if you are not going to be admitted to the hospital. Leave all items such as cash, jewelry, credit cards and other valuables at home. Bring all your medications. Bring all necessary insurance information. Notes: If unable to keep this appointment, kindly give 24 hours notice by calling This information is copied from the Radiology Info Website ( Info.org) which is dedicated to providing the highest quality information. To ensure this, each section is reviewed by a physician with expertise in the area presented. All information contained in the Website is further reviewed by an ACR (American College of Radiology) - RSNA (Radiological Society of North America) committee, comprising physicians with expertise in several radiologic areas.however, it is not possible to assure that this Website contains, complete,up-to-date information on any particular subject. Therefore, ACR and RSNA make no representations or warranties about the suitability of this information for use for any particular purpose. All information is provided as is without express or implied warranty. Please visit the Radiology Info Web site at Info.org to view or download the latest information.

9 This information is copied from the Radiology Info Website ( Info.org) which is dedicated to providing the highest quality information. To ensure that, each section is reviewed by a physician with expertise in the area presented. All information contained in the Website is further reviewed by an ACR (American College of Radiology) - RSNA (Radiological Society of North America) committee, comprising doctors with expertise in several radiologic areas.however, it is not possible to assure that this Website contains, complete,up-to-date information on any particular subject. Therefore, ACR and RSNA make no representations or warranties about the suitability of this information for use for any particular purpose. All information is provided as is without express or implied warranty. Please visit the Radiology Info Web site at Info.org to view or download the latest information.

10 SEPT 04