Science / Medicine : Coronary Balloon Angioplasty Opens an Era : Artery disease: In about a decade of widespread use, the nonsurgical therapy has helped thousands of angina pectoris sufferers, but it isn’t for all patients.
In Switzerland, a little more than a dozen years ago, Dr. Andreas Gruentzig performed for the first time on a human being the medical procedure that is now commonly called coronary balloon angioplasty. The balloon was guided by a catheter inserted into an artery in the leg and fed up toward the heart to the point at which plaque blocked the flow of blood. By inflating the tiny balloon, he opened the channel and restored blood flow.
In a broad sense, this was the beginning of an entirely new era of nonsurgical treatment for coronary artery obstructions that may one day include widely used laser, ultrasound or high-speed drill devices to destroy plaque. Since Gruentzig’s first successful attempt in 1977, balloon angioplasty (known technically as percutaneous transluminal coronary angioplasty, or PTCA) has become one of the most frequently used methods of treating coronary artery disease in America.
More than 30,000 such procedures were performed in 1983. This year an estimated 200,000 angioplasty procedures will be performed--so many that some cardiologists have become concerned that, as Dr. Thomas J. Ryan, chief of cardiology at Boston University Hospital, put it, angioplasty “is being overused in some settings.” So it is important to understand both its virtues and drawbacks.
When is angioplasty called for?
When atherosclerotic plaque--composed of cholesterol, arterial muscle cells, connective tissue and, eventually, calcium deposits--builds up within the wall of a coronary artery and encroaches inward on the channel, so that the artery narrows. As this process continues, it becomes increasingly difficult for blood to flow through the artery. When the heart needs a greater volume of oxygen-rich blood than can be delivered through the blocked vessel, the lack of oxygen sets off the chest pain known as angina pectoris, the cardinal symptom of coronary artery disease.
Until the advent of angioplasty, there were only two types of therapy available for the long-term relief of angina: medical (by the administration of anti-anginal drugs), and surgical (by performing a coronary artery bypass graft, a procedure in which a blood vessel taken from another part of the body is hooked into the blocked coronary artery in such a way as to provide a supplemental flow around the blockage).
For some patients, it is clear that surgery will be superior to medicine in prolonging life; for them, surgery is clearly preferable to medical treatment. However, for many more patients, surgery is not clearly superior.
Angioplasty, like surgery, will restore normal blood flow to the heart. Because it attains the same results as surgery, but is not itself a major operation, it may appear that angioplasty is quite obviously the preferred therapy. Unfortunately, however, not all patients are ideal candidates for angioplasty.
Who is a candidate for angioplasty?
The best candidate is a person with a severe blockage in a single coronary artery that produces angina of such intensity as to cause a marked limitation on exercise, or to seriously diminish the person’s quality of life.
Even with this level of pain, you may not be an ideal candidate for angioplasty under certain circumstances. First, some blockages will not respond to this technique. They are too lengthy or completely calcified or not accessible to the balloon. Second, some patients have too many blockages for angioplasty to do as complete a job in restoring blood flow as can be done with surgery. Third, some blockages, because of their location, present too great a risk. Although the risk of dying during angioplasty is generally low, in some cases (which can be determined by a highly experienced cardiologist), it may exceed the mortality risk of bypass surgery.
Commonly, the factors that affect the risks of bypass surgery have essentially the same effect on angioplasty: Your risks with either procedure will be higher if you are older, are a woman (since women tend to be smaller and thus their coronary arteries present more of a technical challenge), have had prior bypass surgery (since anatomical changes related to your bypass can make the procedure more difficult), or have associated diseases such as kidney failure. Angioplasty carries an additional risk: Within the first six months after the procedure is performed, about 35% of blockages return, although they can be relieved by a repeat angioplasty.
Both medical and surgical therapies have been shown to prolong life significantly, so angioplasty must prove to make a very large difference in life expectancy to displace these competing therapies.
What is known is that angioplasty is easier on the patient than bypass surgery, that it can relieve incapacitating angina as well as surgery and that it can improve your ability to perform physical activity. Thus the frequency and intensity of your angina attacks will probably be the primary guide in assessing whether you should undergo the procedure.
What are the potential complications?
* In about 4% of patients who undergo angioplasty, the artery that is being opened will abruptly close. This may be the result of a clot or a tear in the artery. If this occurs during the procedure itself, you doctor will try opening the artery again by inflating the balloon. But if the repeated inflations do not work, or if the artery closes after the angioplasty procedure is completed, it will be necessary to resort to emergency bypass surgery.
* In about 3.5% of angioplasty patients, a heart attack (myocardial infarction) occurs. Most often this is a result of a closing of the artery during the procedure, although sometimes a smaller side arterial branch may have closed--in some cases, because the procedure has dislodged a blood clot.
* In 1% of angioplasty patients, death occurs during the procedure. (Remember that this and all these percentages represent average rates. “Good” candidates in the hands of “good” doctors and hospitals will be at the favorable end of the range.)
What is the success rate?
About one-third of all patients who undergo PTCA will have a recurrence of the arterial blockage--called restenosis--usually within six months after the procedure.
If restenosis does occur, most patients can undergo another angioplasty. Indeed, it may require three or four angioplasties before the artery remains open. Fortunately, repeat angioplasty has a higher success rate than the procedure has the first time, and with no greater risk of restenosis.
The bottom line:
Once you get six months or a year past a successful angioplasty, you are “cured” of the arterial blockage that was treated. It is extremely unlikely that it will recur.
Nevertheless, you are not cured of the underlying atherosclerosis that caused the problem in the first place. Just what causes coronary artery disease is not known--but certain accompanying risk factors are well known: smoking, obesity, lack of exercise, a diet high in saturated fat, elevated blood cholesterol levels, high blood pressure and diabetes. It is crucial to attend to all these risk factors to lessen the chance of again becoming a candidate for either angioplasty or bypass surgery.
HOW BALLOON ANGIOPLASTY IS PERFORMED
A cardiologist feeds hollow guide through an artery toward the heart and into the affected coronary artery. Next, the doctor inserts a deflated balloon catheter, made of soft plastic, through the guide.
When the catheter has been maneuvered into place, it is inflated several times, for about 60 to 90 seconds. The inflated balloon stretches the diseased artery, increasing the area of flow. The plaque is not removed; the stretching just pushes it out along the arterial wall. When the ballon is removed, the vessel keeps its stretched shape.
