Coronary Angioplasty and Stents
Coronary balloon angioplasty is an invasive method of opening blocked arteries that might impede flow to the heart, and possibly result in heart attack or death. It is more formally known as percutaneous transluminal coronary angioplasty (PTCA): percutaneous means "through the skin," transluminal means "inside the blood vessel," coronary means "relating to the heart," and angioplasty means "blood vessel repair." Other techniques to relieve coronary narrowing, such as stents, are called percutanous coronary interventions (PCI).
Angioplasty involves creating space in the blocked artery by inserting and inflating a tiny balloon, which compresses some of the blocking plaque against the arterial wall. When the balloon is deflated and removed, the plaque still remains compressed, clearing space in the artery and improving blood flow. While angioplasty does not always completely clear an artery, more than 90 percent of all procedures are immediately successful.
Since angioplasty is a less invasive procedure than bypass surgery, it has a quicker recovery period than bypass. However, it is not recommended for all patients. Candidates for angioplasty are chosen based on a patient's age, physical history, and severity of the blockage or damage. The American Heart Association (AHA) and the American College of Cardiology (ACC) have guidelines for prospective angioplasty patients. Your cardiologist will have reviewed these before recommending the procedure for you.
Angioplasty was first performed in 1977, and more than 1 million procedures are done worldwide each year. If this is an elective procedure, the AHA and ACC recommend that you choose a doctor who performs at least 75 procedures each year, at a hospital with a cardiovascular surgical program that handles more than 400 angioplasty cases every year.
Studies suggest that angioplasty patients are doing better today because doctors are better able to target blockages, and because patients are getting better medical treatment through new techniques and drug therapies. The success is due in part to the increased use of tiny wire mesh tubes called stents, which more cardiologists began using in the 1990s to help keep arteries open following angioplasty. These stents form an internal scaffolding to keep the angioplastied vessel from closing. About 70 to 90 percent of all angioplasty patients receive a stent, which is inserted permanently at the site of the blockage.
Stents can be used in a number of ways with angioplasty procedures. A stent may be inserted during an original angioplasty to prevent possible arterial collapse and lower the chance of heart attack and renarrowing of the artery (called restenosis). A stent also may be inserted during a second angioplasty to prevent recurrent restenosis. If restenosis warrants a bypass procedure rather than angioplasty, a stent also may be inserted as part of the bypass procedure. Stents can also be used in the unlikely event that an artery is injured by the catheter. Experienced doctors are able to install stents in one or more arteries with a high probability of success.
The use of stents has decreased the abrupt and unpredictable closure of an artery, which necessitates emergency coronary bypass surgery. Studies show stents are better than angioplasty alone in preventing restenosis, which is one of the most common problems associated with angioplasty.
Some stents are being designed with clot-busting medication, or with radiation, because studies show that both may be effective in preventing arteries from narrowing a second time. Some stents have drugs on them to prevent ingrowth of cells that narrows the blood vessel (drug eluting stents). Researchers have also found that small doses of radiation (called intracoronary radiotherapy or brachytherapy) can reduce the scar tissue that forms around the stent following angioplasty.
In addition, different types of catheters have been designed to remove plaque directly from arteries, a process called atherectomy. These include lasers, a rotating, diamond-encrusted burr that pulverizes plaque, and another device that shaves and deposits plaque into a capsule.
In some cases, cardiologists are also using a new catheter-based procedure called intravascular coronary ultrasound (IVUS) to examine the extent of the blockage, and help them choose the right size balloon and stent to be used during angioplasty.
In approximately one-third of all cases, the blockages return and the artery becomes narrow again. Restenosis can happen within six months of the procedure, and its causes are not entirely understood. It may be linked to newly formed plaque deposits, clot formation caused by the rough, irregular opening created by the original angioplasty, scar tissue from insertion of a stent, or thickening of the arterial wall in response to the stretching of the artery.
Although restenosis is not uncommon, it does not affect every patient, and the prognosis for many angioplasty patients is excellent. Studies have shown nearly identical survival rates for bypass and angioplasty patients over five years following the original procedure.
As explained above, your blocked arteries will be widened. First, a special contrast material is injected into the bloodstream. Then a thin catheter with a guideline is fed into your body through the femoral artery in your leg, near the groin, or an artery in your arm. Using X-rays that detect the flow of dye, the doctor feeds the catheter through the circulatory system, up to the heart, and into the blocked part of the coronary artery. The doctor then replaces the guide catheter with a balloon-tipped catheter. The balloon is inflated, and the plaque is compressed against the arterial wall.
When a stent is used, it is placed over a catheter and inserted after the artery has been cleared using balloon angioplasty. When the balloon is inflated, the stent expands and stays permanently in the artery. The lining of the artery will eventually grow over the surface of the metallic stent.
Advancements in treatment have resulted in angioplasty success rates of 96 to 99 percent. The biggest risk is collapse of the artery, which can trigger a heart attack and requires emergency coronary bypass surgery.
The chance of having a heart attack is between 1 and 3 percent, and the risk of dying during angioplasty is less than 1.5 percent. Emergency coronary bypass surgery rates for angioplasty patients range between 0.2 and 3 percent.
The angioplasty procedure is performed at a hospital or medical center's catheterization laboratory, which is a specially equipped X-ray room, not a traditional operating room. Because of the slight risk of serious complications, the AHA/ACC expert guidelines recommend that elective angioplasty procedures only be performed in institutions that have an experienced cardiovascular surgical team available to perform bypass surgery, if necessary. In emergency situation, only certain hospitals have the facilities to accomplish these procedures. Recent studies suggest that results in facilities without surgical back up during acute myocardial infarctions have reasonably good results.
Depending on your circumstances, your angioplasty procedure may not be scheduled immediately and you will have time to discuss the situation with your family. A scheduled angioplasty is often performed as a result of a blockage found during a catheterization (sometimes due to stress test results). Your doctor may have discussed the options of bypass surgery versus angioplasty with you, and you may wish to discuss these issues with your family.
Angioplasty can, however, occur as an emergency treatment for heart attack or cardiac arrest. As with any emergency situation, you and your doctor will want the procedure performed as quickly as possible.
You will be asked to refrain from eating and drinking anything after midnight on the night before the procedure (with slight modifications for patients with diabetes). It is important that you follow these and any other instructions carefully.
Depending on the severity of the blockage and the number of blockages, the procedure can take anywhere from 30 minutes to three hours to complete.
You may be given a sedative to help you relax. The procedure is performed under local anesthesia, instead of general, because you need to be awake to move, cough or breathe when asked to do so.
The general consensus among patients is that angioplasty is a sometimes uncomfortable, but not painful, procedure. You may feel some twinges in your chest when the balloon is inflated, but once the blockage is compressed, the pain should disappear. You also may feel nauseous, feel your heart skip, or have a headache during the procedure; these are all normal, brief side effects.
Let your doctor know whatever symptoms you are feeling during the procedure. You will be on an IV line throughout the procedure, and can be given medicine as needed for pain or discomfort. You also may be given additional sedatives during the procedure so that you are able to remain motionless, but awake.
The procedure must take place in a germ-free environment, so all medical personnel will be wearing surgical scrubs. No observers will be permitted. Friends and family usually remain in a waiting room near the catheterization laboratory. Ask your doctor about the specifics for your hospital.
You will probably feel some discomfort on the day of, and following, the procedure. Pain medication is available, and you should let your doctor or nurse know if you are experiencing additional discomfort.
You will need to rest quietly in a recovery room for a few hours after the procedure, and then moved to a regular hospital room. You can generally go home within 24 hours, if your blood tests, electrocardiogram and blood pressure are normal.
If the procedure is successful, you will be able to eat again shortly in recovery.
The catheter usually remains in your groin area for 12 hours to 24 hours in case a second, emergency procedure is required. Because of this, you will have to keep your leg immobile, so you must remain in bed for at least this period.
In most cases, there are few restrictions placed on activity, pending an evaluation by your doctor.
If you have received a stent, you will be prescribed an anti-clotting medication for several months. You can expect to be on high dose statins to control your cholesterol, even if it has not been terribly high.
Glycoprotein IIb/IIa receptor blockers, aspirin, clopidogrel, ticlopidine, or heparin may be part of your drug regimen.
You also may receive special medication to help your arteries heal. Depending on your condition and health history prior to the procedure, your doctor may prescribe additional cholesterol-lowering medications or other new medications.
A recurring blockage (restenosis) occurs in about one-third of the successful angioplasty procedures performed this occurs far less frequently when a stent is inserted. A doctor might choose to do additional angioplasty, add a stent if it was not installed previously, or recommend bypass surgery.
Following this procedure, you will need to see your doctor for an evaluation and possible stress test to measure how effectively the blockage was eliminated. You will be encouraged to exercise regularly and your doctor will want to see you several times a year to make sure no more blockages have occurred.
While some of the causes (age, gender, family history) of coronary artery disease are out of your control, there are lifestyle choices that often contribute to blockages. Some of these are obesity, smoking and physical inactivity. While these factors can contribute to your condition, they can be modified. Receiving appropriate treatment for other cardiovascular risk factors such as high blood pressure, diabetes, and high cholesterol can also reduce the likelihood of developing severe coronary blockages.
Eliminating restenosis is not completely within the patient's control. Under ideal circumstances including a low-fat diet, use of medications and exercise, additional plaque and blockages should not form. However, restenosis can occur for a variety of reasons, some of which have to do with the artery's ability to heal or the strength of the arterial walls.
The best advice is to follow your doctor's instructions and be vigilant about following up with stress tests. This will ensure that future blockages are detected and treated quickly. If you experience any chest pain or discomfort, contact your doctor and seek medical help immediately.