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Heart Stents

Examining new research on and uses for stents -- spring-like devices that keep heart patients' narrowing arteries open. Susan Dentzer reports.

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  • SUSAN DENTZER:

    Before his most recent bout of chest pain, Vice President Cheney last underwent heart treatment in November. That's when he suffered a mild heart attack, his fourth in 22 years. When he arrived at George Washington University Hospital in November, doctors performed a so-called "cardiac catheterization" to probe for blockages in his coronary arteries. When they found one, they took action.

  • DR. JONATHAN REINER:

    We deployed what we call a stent in Mr. Cheney's diagonal artery. A stent is a stainless steel mesh. It's crimped onto a balloon, and when the balloon is expanded, the stainless steel mesh is also expanded, and is essentially embedded into the wall of the artery, and it acts like a tiny stainless steel scaffold to sort of buttress the wall of the artery and keep the artery open.

  • SUSAN DENTZER:

    That might have been the first time many had heard of stents, devices that look a bit like the spring of a ballpoint pen. Over the past decade, stents have prompted big changes in the way patients like Cheney are treated. Now they're even edging out cardiac bypasses as the treatment of choice for many. In the U.S. alone, roughly 400,000 people a year are treated with stents, while sales of the devices are approaching $3.5 billion a year. Marvin Woodall helped to develop some of the earliest stents at Johnson & Johnson Company in the 1980s.

  • MARVIN WOODALL:

    I thought that possibly stents could be used in as high as 25 percent or 30 percent of patients, but today it seems to be like it's in 85 percent to 95 percent of patients.

  • SUSAN DENTZER:

    From his first heart attack in 1978 to his new stent, Cheney's years of heart treatment encapsulate the many rapid advances in cardiac care. He's long suffered from coronary heart disease, in which cholesterol and fat in the blood build up in clumps known as plaque on the inside walls of arteries. The plaque can so restrict the flow of blood, oxygen, and nutrients that it leads to a heart attack, when part of the heart muscle starved for oxygen begins to die.

    Cheney suffered one such attack when he was in his late 30s, and two more when he was in his 40s. After the third heart attack in 1988, Cheney had a quadruple bypass operation. Pieces of another blood vessel in his body were grafted onto four blocked arteries to create new channels for blood flow. These bypasses are major operations that, among other things, require cutting through the breastbone, or cracking the chest, as it's called, to operate on the arteries. To avoid that invasive surgery, doctors developed a new procedure called balloon angioplasty. Dr. Kenneth Kent, a heart specialist at Georgetown University Hospital, describes the breakthrough.

  • DR. KENNETH KENT:

    A very aggressive pioneer found that he could relieve some of the obstructions of the coronary arteries by putting a balloon in the coronary arteries, dilating it, pushing the plaque out of the way, and allowing blood flow to the heart.

  • SUSAN DENTZER:

    The procedure quickly became popular but angioplasties also had serious drawbacks. Sometimes during the procedure blood vessels would be damaged and would shut down. That meant surgeons had to be called in to perform emergency bypasses. And even with angioplasties that appeared successful at first, problems could follow months later for patients.

  • DR. KENNETH KENT:

    They would have recurrent chest pain. They would come back, we would take another angiogram, and the narrowing… the vessel would have renarrowed to exactly the same degree, or sometimes even worse than they had the first time.

  • SUSAN DENTZER:

    Doctors discovered that blood vessels sometimes shrank in response to minute injuries from the balloons. That's when doctors devised stents, to be used in conjunction with angioplasties to make sure that arteries, once unblocked, would stay open. Brian Firth of Cordis, the Johnson & Johnson division that makes stents, says that at first the idea seemed strange.

  • BRIAN FIRTH:

    The concept of stenting was on the one hand very controversial, because many people thought that putting a piece of metal into an artery and leaving it there long-term might be a bad idea. These things might break; they might get infected.

  • SUSAN DENTZER:

    But clinical trials to test the devices on patients showed otherwise.

  • BRIAN FIRTH:

    There was a much lower rate of renarrowing of the vessel, and a much lower rate of repeat intervention in these patients who had stents as opposed to angioplasty. These were simple, elegantly designed little tubes that are put into patients that worked. They didn't break. They lasted. They provided very good scaffolding for the vessel.

  • SUSAN DENTZER:

    The Federal Food and Drug Administration approved stents for treating patients in 1993. Since then, stent design and production has changed dramatically. Although stents were once made by soldering wires together around a pencil, today they're made from steel tubes etched by computer-controlled lasers.

  • SUSAN DENTZER:

    At the same time, the ranks of so-called interventional cardiologists, like Dr. Kent of Georgetown, have swelled. Recently Kent performed an angioplasty and stenting procedure on 41-year-old Mark Hyson of Oakland, Maryland. A smoker with high cholesterol, Hyson suffered a bad heart attack last December. He was given a clot-busting drug that broke up blockages in his arteries. But later, his chest pain recurred, a fact that Kent says made him a prime candidate for an angioplasty and stent. With Hyson sedated but awake, the procedure began with insertion of a catheter, or long tube, into a blood vessel at the top of his leg.

  • DR. KENNETH KENT:

    The guide catheter then goes up through the major artery, the aorta, and then we thread this small guide wire through that guide catheter, through the blockage, and place the guide wire further down the artery.

  • SUSAN DENTZER:

    With the aid of ultrasound, Kent and his assistants identified two blockages in Hyson's artery.

  • DR. KENNETH KENT:

    What we see now is the plaque mass here is increasing and the channel is getting smaller.

    So we put two stents– one very short stent farther down the vessel and then the much larger and somewhat longer stent in the proximal portion of the vessel, and that was plaque that caused the original heart attack.

  • SPOKESMAN:

    Mr. Hyson everything went fine. We're all through. Everything looks great.

  • SUSAN DENTZER:

    The procedure took about 40 minutes – similar to Cheney, who spent just two nights in the hospital before resuming much of his normal activity, Hyson expected to go home the next day.

  • MARK HYSON:

    I think they'll keep me tonight and check me out; keep an eye on me, but I think I'll go home tomorrow.

  • SUSAN DENTZER:

    Hyson's follow-up regimen is to quit smoking and take prescription drugs similar to those given Cheney. These represent still more major innovations in cardiac care; they include powerful statin drugs to lower cholesterol and a so- called ACE inhibitor to help mend Hyson's damaged heart muscle.

  • DR. KENNETH KENT:

    If we can control his risk factors, we can get his cholesterol down with statin drugs, then he should have an excellent prognosis.

  • SUSAN DENTZER:

    Despite the advantages of stents, they're not a perfect solution, as Vice President Cheney discovered this week. His cardiologist, Jonathan Reiner, explained yesterday what might have happened.

  • DR. JONATHAN REINER:

    You know, what we know is that when an artery is stented, you know, the stent is a foreign body, and the stent itself initiates a series of events, normal events– response-to- injury events which in about 20 percent of patients results in renarrowing.

  • SUSAN DENTZER:

    To treat Cheney yesterday, doctors cleared out the artery and reopened the stent with a balloon. And they said they'd continue to monitor his chronic condition.

  • DR. JONATHAN REINER:

    The Vice President clearly has chronic coronary artery disease, and he has probably had it for many decades, although it was first discovered when he had his first heart attack in the 1970s. And this is what coronary artery disease has become. It's become a chronic disease. I wish I could predict the future. I think there's a very high likelihood that he can finish out his term in his extremely vigorous, vigorous capacity.

  • SUSAN DENTZER:

    His doctors also said yesterday that they were evaluating other treatment options.

  • DR. JONATHAN REINER:

    If the narrowing were to come back, you know, there are evolving technologies which are really only now becoming available to further prevent that, and that would include things like delivering inter coronary radiation therapy to the stent.

  • SUSAN DENTZER:

    That therapy is designed to inhibit further scarring. And still other new advances may reduce the chances of arteries renarrowing in the future. One is stents specially coated with medications that provide an extra measure of protection to keep arteries open. Johnson & Johnson has begun selling one stent coated with the blood-thinning drug Heparin, which deters formation of blood clots. The company is also testing other types of drug-coated stents on patients. As a result, some experts predict the use of stents will continue to grow.

  • BRIAN FIRTH:

    Bypass surgery is likely to go down much more quickly than it has, and interventional procedures are likely to grow more rapidly than they have.

  • SUSAN DENTZER:

    And it's all just a part of an ongoing revolution in cardiac care, one that may yet help to prevent still more of the suffering of patients.

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