Interventional Radiology

Angioplasty & Stenting

In this technique, the interventional radiologist inserts a very small balloon attached to a thin tube (catheter) into a blood vessel through a small nick in the skin. The catheter is threaded under X-ray guidance to the site of the blocked artery. The balloon is inflated to open the artery.

Stent

Stent placement
Stents are used to hold open areas of arteries narrowed by artherosclerosis

Sometimes, a small metal scaffold / tube, called a stent, is inserted to hold the blood vessel open. 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.

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. The radiologist or a staff person will ask you to sign a consent form that covers angioplasty. It also will cover angiography, an x-ray study of the arteries involving injection of contrast material.

Make sure that the 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 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 possibly make you drowsy. It will stay in place until angioplasty is completed.

What Does The Equipment Look Like?

Angioplasty and stent placement are monitored as they take place using high-resolution angiography equipment.

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 so that in each case it matches the size of the diseased artery.

How Does The Procedure Work?

Angioplasty
Inflating a baloon at a narrow location within an artery

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 it 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 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 a 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 also may be placed to keep an artery open if the inflated balloon has torn or damaged it. Some modern stents are covered with a drug that helps keep the artery open; they seem to improve the long-term success rate.

How Is The Procedure Performed?

The first step is to set up an intravenous line and use it to give a sedative. 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 up into 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. 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.

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 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 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 back pain for renal angioplasty, and buttock pain when iliac angioplasty is performed.  After the procedure, the sheath will be removed and pressure applied  to the incision.  Occasionally, a collagen plug or suture may be used to assist in closure of the incision. You will have to remain flat on your back and avoid moving your leg or groin for about six hours to allow the incision to heal. Most patients will be able to walk about 6 to 8 hours after angioplasty. Most patients return home the same day, but some stay in the hospital for a short time.

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 (sometimes longer if you had a suture or plug placed), 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 doctor 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 or in the treated limb.

If a stent has been placed, you will be asked to take aspirin or another anti-platelet drug indefinitely. MR imaging should be avoided for a month unless a radiologist approves the study. Metal detectors will not affect the stent.

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.

What Are The Benefits Vs. Risks?

Benefits

  • Angioplasty, with or without stenting, is much less invasive than open surgery, which in the case of  blocked arteries means a bypass operation. When angioplasty succeeds, major surgery and the risks of general anesthesia are avoided. Overall cost is much less, and the hospital stay is days or hours 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 nearly the same length of time. Even after bypass surgery, some of the new blood vessels occasionally become blocked.

Risks

  • With angioplasty alone, an estimated one in ten blockages recur in a few months, though most of these arteries can be successfully dilated again. The chance of this happening is less when a stent is placed.
  • The risk of serious effects from angioplasty is substantially lower than open surgical procedures. There is a rare risk of vessel rupture, which could require surgery or be life threatening.
  • 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 or even surgery to correct.
  • There is a risk of stroke when angioplasty is performed on the carotid artery and a stent is placed. 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.

What Are The Limitations Of Angioplasty And Vascular Stenting?

  • In a small percentage of cases, angioplasty—even with stent placement—fails to increase blood flow bypass surgery is 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.
  • Sixty to seventy percent 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 patients have disease in small arteries within the kidneys that cannot benefit from angioplasty. Renal artery angioplasty with stenting causes complications in about 10 percent of patients, though few of them are major. As in coronary angioplasty, the dilated artery may again become narrowed, with hypertension the result.
  • Angioplasty/stenting for arterial disease in the pelvis and legs is less successful when there are narrowed arteries 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 proved 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.

 

To get more information or to schedule a procedure, please call Vascular & Interventional Associates 859-341-4VIA (4842).