Using Radiation to Fix a Mean

 

 

By DANIEL Q. HANEY

AP Medical Editor

 

BOSTON (AP) – The first hour of the angioplasty went normally, assuming of course that shoving wires, balloons, drills and other gadgetry into the heart of a wide-awake man can ever be consid­ered normal. But then something out of the ordinary happened.

Dr. Daniel Simon leaned toward his patient, who was covered neck to toe in sterile blue cloth. Even with his glasses on, the patient could see nothing but a big X-ray camera hanging overhead. Out of view were 10 doctors, nurses and technicians, all wearing knee-length lead vests and waiting for this moment.

“Mark, we’ve got the artery wide open,” Simon said in a reassuring voice. “Now we are going to irradiate.”

Radiation in the form of X-rays has long been used during heart procedures to take pictures of the work in progress. But this was different. The doctors were about to try to fix a bad heart using the same kind of radiation usually reserved for killing cancer.

Such a seemingly extreme approach was necessary, at least in part, because the other technology in the small, crowded room had already made this bad heart even worse. Except for his young age­38-the patient was a typical failure of modern cardiology.

What first brought him here was angina, the pain that seized his chest whenever he did anything demanding, like ride a bike. The problem was his heart’s right coronary artery. Last win­ter, doctors discovered it was two-thirds plugged. So his heart’s own muscle was starved of oxygen-carrying blood. At the time, the solution seemed obvious: He needed an angioplasty.

In 23 years, this procedure has grown to be one of the most common big-ticket treatments in medicine, now done about 750,000 times a year in the United States.

Common, but hardly foolproof, and certainly not for Mark. He became one of the unfortunate, sizable minority whose angioplasties go bad.

Within a few weeks, the pain was back, worse than before. Now his chest hurt even when he did nothing. The reopened artery had clogged with a vengeance. The medical word for this is “restenosis,” and in Mark’s case, it meant the flow of blood was 99 percent blocked.

Doctors repeated the procedure, but the result was the same. So now, five months and two angioplasties later, Mark was back in the cardiac catheteri­zation lab, two stories below ground at Brigham and Women’s Hospital, ready for something new.

The doctors began the job by thread­ing a delivery tube from his groin up into his heart. First, they sent in a tiny diamond-tipped conical burr. Spinning at 180,000 rpm, it chewed through the gunk that clogged his artery. Next they inserted a skinny sausage-shaped bal­loon. When briefly inflated, it squeezed the artery a little wider, leaving a reason­ably normal three-millimeter opening.

Now came something called the Beta­-Cath system. This rig is a gun the size of an electric drill that uses hydraulic pres­sure to drive seeds of radioactive stron­tium 90 through a catheter into the heart. Simon maneuvered the catheter into Mark’s bad artery.

A radiation oncologist-the only specialist licensed to deliver this pow­erful stuff-held the gun and pushed the switch, sending in the seeds. A technician counted down the seconds, “30 . . . 29 . . . 28 . . .” In half a minute, the seeds returned to the gun, and it was over.

Around the world, perhaps 6,000 heart patients have been treated with radiation this way, most of them-like the Boston patient-in formal research studies. However, radiation could be routinely available within a year. Novoste Corp. of Norcross, Ga. recently asked the Food and Drug Administra­tion for approval to sell its Beta-Cath. Competing systems are being developed by Guidant Corp. of Indianapolis and Johnson & Johnson’s Cordis unit, among others.

Radiation has long been viewed as the heaviest of medical artillery. That cardi­ologists would even consider using it against their old nemesis, restenosis, shows just how close to wits’ end they have come.

This is the latest in a succession of medical technologies intended to pre­vent or correct what happened to Mark. Most were used enthusiastically for a year or two, then abandoned when they proved no better, and sometimes worse, than plain balloon angioplasty.

“For the longest time, restenosis has been the Achilles’ heel of interventional cardiology,” says Dr. Tony Farah of Allegheny General Hospital in Pitts­burgh.

From the very start, actually. Dr. Andreas R. Gruentzig did the first bal­loon angioplasty in 1977 in Zurich with equipment he designed in his kitchen. Soon it became apparent that reopened heart arteries often closed off again within six months or so.

Nevertheless, angioplasty took off. Its power to make people feel better instantly –and get out of the hospital in just a day – made it an attractive alterna­tive to the rigors of coronary bypass surgery.

But it was always a gamble. After one­-third to one-half of seemingly successful angioplasties, the artery clogs up again. In half the cases where this happens, the renarrowing is so severe that patients need another procedure – either a repeat angioplasty or a bypass operation.

Over the years, engineers tinkered with many clever but ultimately ineffec­tive solutions. Whirring knives carved the buildup away; lasers burned it off. While the diamond-tipped burr and a few other methods are still used occa­sionally, none does much in the long run to prevent restenosis.

Until now, the only thing to make any difference is something called a stent. These elegantly designed stainless steel mesh tubes are the one true breakthrough of the first two decades of angioplasty.

Cardiologists push the folded-up stents into place after an angioplasty bal­loon squeezes open the artery. There the stents spring open and lock, acting as stiff metal scaffolds to prop the artery open.

This prevents the most common cause of failure after ordinary balloon angio­plasty, which is artery recoil. The artery wall is springy like a rubber tube, and without a stent it often just returns to its original shape when the balloon is gone.

Studies show stents reduce angio­plasty failure by about 40 percent, but many experts doubt they are truly that effective. Almost nothing in medicine works as well in everyday practice as it does in formal studies, where patients tend to be healthier and better cared for.

Nevertheless, more than 80 percent of patients get stents during their angioplas­ties, despite questions about whether this IS necessary.

Dr. David Brown of Montefiore Med­ical Center in New York City reviewed more than 44,000 angioplasties done in California in 1997. His conclusion: About 20 percent of all patients eventu­ally needed a bypass operation or repeat angioplasty, regardless of whether or not they got stents.

However, preventing restenosis is not the only reason for stents’ popularity.

The biggest health risk after an angioplasty is the abrupt total blockage of the artery, something that can hap­pen in the first few days after the proce­dure. It occurs when a flap of artery wall is torn loose during the angio­plasty and drops down to plug the flow. Unlike garden-variety restenosis, this is a life-threatening crisis. It complicates 3 percent to 5 percent of angioplasties and usually requires emergency bypass for repair.

Stents plaster back these tears so they cannot trigger disaster. “Stents have almost eliminated the need for emer­gency bypass surgery as a complication of angioplasty,” says Dr. Larry S. Dean of the University of Alabama in Bir­mingham.

But stents also create a new prob­em – a particularly intractable variety of restenosis, the very thing they were designed to prevent. Stents spur the growth of scar tissue over the damage left by the balloon. These cells can luckily grow through the stent’s steel flesh, sometimes entirely filling the artery.

This turns out to be a problem for perhaps 15 percent to 20 percent of stent patients, and it is hard to fix. Doctors can ream out the plugged stent with burrs and balloons, but the artery usu­ally fills up again.

The need to control renarrowing worsened by stents explains doctors’ willingness to experiment with radia­tion. The idea is to kill the rapidly dividing cells that form scar tissue. Without this growth, the thinking goes, stent­-braced arteries will keep flowing.

The first U.S. doctor to try this was Paul Teirstein of the Scripps Clinic in San Diego. His first patient happened to be a fellow physician who had endured five failed angioplasties in 10 months. The man pleaded for something new. Teirstein mentioned experiments in rab­bits and pigs showing that radiation might prevent recurring blockage.

“ ‘If it works in pigs, it will probably work in me,’ ” Teirstein remembers the man saying. “We irradiated him, and it worked. He didn’t have any more rrestenosis.”

That was 1994, and it began the devel­opment of the competing radiation approaches that are nearing Food and Drug Administration approval.

The technologies differ somewhat. Some, such as the Beta-Cath, use beta radiation that penetrates only a few mil­limeters into the artery, so doctors and nurses can stay in the room without get­ting hit by it. Other systems use farther ­reaching gamma radiation, so everyone but the patient must leave the room while the artery is being zapped.

While the various techniques have not been compared head to head, they seem roughly equal, reducing the return of restenosis by between one-third and one-half.

Whether radiation will work this well for Mark remains to be seen, since the regrowth that blocks stents can take sev­eral weeks.

From what they have seen so far, many doctors are convinced radiation will be a routine part of heart treatment, at least until something better comes along.