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The High-Tech Heart

By: Source: AARP Bulletin Today Date Posted: 2003-09-02 15:40:00-04:00

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The nation's number-one killer is still on the prowl, claiming new victims every day, but investigators who have been in hot pursuit for years are convinced they are closing in on it and will soon end many of its worst ravages.

The killer is heart disease, which last year caused almost one of every five deaths in the United States—and one of four in people 60 and over.

Trackers of the disease take immense satisfaction from the fact that heart disease deaths have decreased by almost 25 percent over the past decade. But, with an exuberance uncommon in science, heart specialists believe they are on the brink of an era that promises even greater progress.

Their enthusiasm is solidly based. Research under way in hundreds of medical centers is producing new knowledge and giving physicians better tools to diagnose and repair heart problems before they reach the fatal stage.

And while there is no "cure" for heart disease given its many complex varieties, evidence keeps growing that individuals can help ward off heart disease by adopting a healthy lifestyle.

"It's going to be harder to die of heart disease in the future," S. Ward Casscells II, M.D., predicts confidently.

Casscells, chief of cardiology at Hermann Hospital in Houston, says more attention to nutrition, vitamins and exercise will certainly help. "And there's no doubt," he predicts, "that it will be routine to implant an artificial heart when your own heart has failed."

HEART TRANSPLANTS POSSIBLE

"They've just cloned this sheep called Polly that has human genes in it," he says. "I have zero doubt that within five to 10 years pigs will grow to a certain size with human hearts. Not only that, but it will be a human heart that will be transplantable [without the markers] that say 'I'm a pig' to alert the human immune system to reject it."

But the prospect of routine heart transplants is only one of a number of developments, some resembling science fiction, that excite experts.

They include:

• gene therapy,
• new and more effective clot-busting drugs,
• " keyhole " and other less invasive surgical techniques,
• imaging technology advances that make it possible for physicians to see more clearly into the heart's innermost chambers than before,
• laser surgery,
• such bold innovations as " heart remodeling " and
• massive research into such factors as the root causes of arterial blockages and the role played by genetic predisposition.

Still, as Alan Wasserman, M.D., a cardiologist and chairman of the department of medicine at George Washington University, puts it, heart disease is "a very strange disease that doesn't follow any rules" and yields its secrets reluctantly.

A HEAVY ANNUAL TOLL

Various cardiac malfunctions will cause heart attacks in about 1.5 million Americans in the coming year, killing one-third of them within 20 days. About 30 percent survive 10 years after a heart attack.

While about a fifth of all attacks are "silent," coming and going without immediate detection, the deadliness of the rest is enhanced by their shocking suddenness.

"For 100,000 people a year," Wasserman says, "the first symptom is that they die suddenly. For a lot of other people, the first warning is the heart attack itself; they get chest pains, but they are fortunate enough to survive it. For another group, there are no symptoms: It's just discovered one day, maybe with an electrocardiogram (ECG), that they've had a [so-called silent] heart attack."

During checkups, says Wasserman, your doctor will seek first to identify risk factors and emphasize prevention.

A routine physical exam can assess the probability of having a heart attack. In addition, an accurate recall of family history is important, because some people inherit a genetic predisposition for heart disease. Other indicators of possible trouble ahead are high cholesterol, obesity, hypertension and diabetes—all of which can be modified through medication or a lifestyle change.

For people with these profiles especially, it is essential to avoid risky behavior that can promote heart disease. This includes smoking, poor diet and lack of exercise.

The heart problems that can assail a person vary.

For some, the problem may be in the heartbeat, an electrical wave that sweeps over the heart in a concentrated and coordinated way. If this "natural pacemaker" is not working properly or if the electrical pathway is blocked, an artificial pacemaker designed to regulate this "ticking" can take over.

Such pacemakers, implanted under the skin with a lead extending to the right side of the heart, are getting smaller and smaller, while their batteries are lasting longer.

ARTERY PROBLEMS COMMON

The most common heart ailment, however, is coronary artery disease, or arteriosclerosis, resulting from a buildup of plaque that narrows the arteries and deprives the heart of a proper blood supply.

There is general agreement that such buildup usually results from a diet too rich in animal and dairy fats. Lack of exercise and smoking can also help obstruct arteries.

These obstructions can be seen in amazing detail with ultrafast CT scanning devices. The new diagnostic machines, available in a few major hospitals, fire X-ray beams 10 times faster than older models. The result is a blur-free picture of the arteries and any possible calcium buildup, an image unaffected by the movement of blood or the pulsing of the heart.

Most often, evidence of inadequate blood flow to the heart muscle can be determined by a stress test. If such tests are inconclusive or indicate significant artery disease, angiography follows. Also known as cardiac catheterization, this procedure involves the insertion of a catheter (a tubular probe) through the artery. This supplies a detailed picture of blood flow and any blockage. The physician can then recommend medication or corrective intervention.

The most common intervention is balloon angioplasty, in which an obstruction in the blood vessel is pushed aside. The technique has saved many lives, but it has a high failure rate and often has to be repeated.

In 1994, however, the U.S. Food and Drug Administration approved the use of the Palmaz-Schatz stent, a flexible metal device designed to prevent the collapse of a vessel that has been opened. It is now the workhorse in cardiac procedures, according to Daniel Spyker, who heads the cardiovascular devices division at FDA.

"It's really the first interventional device that has had a real demonstrated benefit over balloons," he says, adding that some clinicians are inserting them in vessels with a very small diameter.

Indicative of the wave of technological improvement now under way, many companies are testing variations of the stent, applying coatings to prevent infection and in other ways enhancing its use.

But for many patients, especially those with multiple blockages, angioplasty is no remedy, and surgery is the only option.

BYPASSING THE PROBLEM

The coronary artery bypass graft—"bypass surgery"—was once considered radical, but constant improvements in technique and technology have made it almost commonplace. Although the procedure is performed almost a half-million times a year, it remains a major, expensive operation.

Surgeons make a foot-long incision in the chest, cut open the breastbone with a saw, pry open the rib cage and stop the exposed heart as they reconfigure the blood vessels. This is usually done by taking a vein from the leg and surgically implanting sections of it in the chest, forming a bypass around each blocked artery. The procedure has a high success rate, but the patient must undergo a long, painful recuperation.

In recent months, however, hundreds of surgeons have been trained in a new, gentler approach, sometimes called keyhole surgery. Aided by fiber optical scopes and other instruments, the surgeon makes repairs to the heart vessels through small cuts between the ribs.

This avoids the massive chest damage inflicted by open-heart surgery and reduces pain, recovery time and hospital bills. It is still considered experimental, however; many surgeons think its application may be limited to one or two blockages, and no one yet knows how effective it will be long term.

At the University of Colorado School of Medicine in Denver, cardiologist Michael Bristow is using beta-blockers—medication that protects the heart from excessive stimulation—to reverse the process that can cause the heart to become enlarged and overworked.

Work is also under way with laser technology, using lasers to burn away diseased cardiac tissue. But this is still a distant promise. A technique for burning new channels through the heart to permit renewed blood flow was rejected in 1997 by an advisory panel of the FDA.

A BOLD NEW APPROACH

But perhaps the boldest and most controversial new surgical technique involves remodeling the heart to improve performance by reducing its size. A Brazilian surgeon, Randas Jose Vilela Batista, has developed this radical operation that changes the pumping function by cutting away as much as a third of a diseased heart.

On another front, Casscells, the Houston cardiologist, is particularly impressed with research on the growth of blood vessels. Scientists in Boston recently were able to "turn off" genes that promote cell growth in the inner linings of veins used in bypass surgery, and other researchers have applied gene therapy to help patients grow new vessels around blocked arteries. There is also talk of individuals growing heart valves from their own tissue.

Paralleling research into treatment of heart disease is work on understanding its causes and prevention.

For example, various researchers are seeking to identify genes that predispose some people to heart disease; to determine genetic causes of failing heart muscles and congenital heart disease; and to understand how congestive heart failure occurs.

Congestive heart failure, a condition in which the heart can't pump enough blood to meet the needs of the body's other organs, is the most common diagnosis in hospital patients 65 and older. With slow blood flow, congestion of the tissues occurs, causing, among other things, swelling in the legs and ankles and shortness of breath.

Treatment usually includes rest, a proper diet, modified activities and drugs such as digitalis (to increase the pumping action of the heart), diuretics (to eliminate excess water) and vasodilators and ACE inhibitors to expand blood vessels.

FOCUS ON PREVENTION

Preventing heart disease is also receiving enormous attention. The reason is obvious, says GWU's Wasserman: "It's a lot easier to treat this disease before the heart attack than afterward."

An aspirin a day has, of course, been accepted as a standard prevention measure, useful in keeping blood clots from forming. Folic acid and vitamins B-6 and B-12 can lower levels of homocystine, a naturally occurring and potentially harmful amino acid.

Researchers say they have new evidence that omega-3 fatty acids, found in seafood, can cut the risk of heart disease. There is also widespread agreement that everyone should reduce the intake of saturated fats, eat more fruits and vegetables and add high-fiber grains and soy products to the diet. And there are indications that daily doses of vitamins E and C can help. They are antioxidants that help control cell damage caused by oxygen as it moves through the bloodstream.

For preventing that second heart attack, hospitals offer classes in cardiac rehabilitation that include monitored exercise programs and psychological support. Despite the proven benefits of these classes, however, fewer than one-fifth of heart attack survivors enroll.

Most Americans know that smoking, physical inactivity and being overweight are unhealthy. Yet relatively few people take steps to improve these conditions.

Concerns over these human factors have led to calls for a different sort of research, into behavior modification and ways to ensure long-term compliance with healthy habits.

Except in a relatively few cases where built-in physical defects are very severe, most of us have the ability to prevent or lessen the effects of heart disease by adopting a healthier lifestyle. The question is: Will we?

This article previously appeared in the AARP Bulletin. Since its original publication, there may have been some medical developments in this area. Therefore, consult your physician for the latest information and advice on treating this particular condition. The information in this article is intended only to describe this medical issue in general terms. This information should not be used as advice regarding your particular condition. Only your physician can give you proper medical advice.

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