Artificial valves hold hope for hearts
The procedures, still at an experimental stage, do not require open-heart surgery and dramatically reduce recovery time.
Published April 2, 2006
Dr. Samuel Lichtenstein cut a 2-inch hole between an elderly man's ribs. Peering inside, he poked a pencil-sized wire up into the chest, piercing the bottom of the man's heart.
Within minutes, Bud Boyer would have a new heart valve - without having his chest cracked open.
Call it closed-heart surgery.
"I consider it some kind of magic," said Boyer, who left the Vancouver, British Columbia, hospital a day later and was almost fully recovered in just two weeks.
In Michigan, Dr. William O'Neill slipped an artificial valve through an even tinier opening. He pushed the valve up a patient's leg artery until it lodged in just the right spot in the still-beating heart.
The dramatic experiments, in a few hospitals in the United States, Canada and Europe, are designed to find easier ways to replace diseased heart valves that threaten the lives of thousands of people every year. The experiments are starting with the aortic valve that is the heart's key doorway to the body.
The need for a less invasive alternative is great and growing. About 50,000 people in the United States have open-heart surgery every year to replace the aortic valve. Surgeons saw the breastbone in half, stop the heart, cut out the old valve and sew in a new one. Even the best patients spend a week in the hospital and require two months or three months to recuperate.
Thousands more are turned away, deemed too ill to survive that operation and out of options. Demand is poised to skyrocket as the baby boomers gray; the aortic valve is particularly vulnerable to rusting shut with age.
The new experiments are a radical departure from that proven, if arduous, surgery.
The artificial valves do not even look like valves, squished inside metal cages until wedged into place. Barely 150 of any type have been implanted worldwide, most in the past year. It is unclear if they will work as well as traditional replacements, which last decades.
For now, the only patients who qualify for these valves are too sick to be good candidates for regular valve replacement.
Some deaths during the earliest attempts at implanting the devices forced doctors to come up with safer techniques. Clinical trials apparently are back on track, and even the most skeptical cardiologists and heart surgeons are watching how these pioneers fare.
The hope is that one day, replacing a heart valve could become almost an overnight procedure.
"There's lots of technical challenges that need to be overcome," said Dr. Robert Bonow, a valve specialist at Northwestern University, who is monitoring the research for the American Heart Association. "Most of us do think this is the future," he said.
O'Neill's first successful patient in March celebrated the first anniversary of his through-the-leg implant. "I call it a new birthday," chuckled Fred Grande, 78, a Richmond, Mich., car collector who took one of his beloved models for a fast spin less than a week after the procedure.
"That's the home run we want to hit with all the patients," said O'Neill, cardiology chief at William Beaumont Hospital in Royal Oak, Mich.
"It's gratifying" to watch people once deemed beyond help bounce back, added Dr. Jeffrey Moses of New York-Presbyterian Hospital/Columbia University, who with O'Neill is leading the U.S. study. One of Moses' first patients is playing golf at age 92.
The heart has four valves, one-way swinging doors that open and close with each heartbeat to ensure blood flows in the right direction. More than 5-million Americans have moderate to severe valve disease, where at least one valve does not work properly, usually the aortic or mitral valves. Worldwide, roughly 225,000 valves are surgically replaced every year.
Topping that list is the aortic valve. It can become so narrowed and stiff that patients' hearts wear out trying harder and harder to push oxygen-rich blood out to the rest of the body.
With minimally invasive valve replacement, doctors do not remove that diseased valve. Instead, they prop it open and wedge an artificial one into that rigid doorway. "It's ironic. You use the disease process to actually help hold your valve in place," said Lichtenstein, of St. Paul's Hospital in Vancouver, who helped create the between-the-ribs method.
Irvine, Calif.-based Edwards LifeSciences, the biggest maker of artificial heart valves, and Paris-based CoreValve are testing versions of a collapsible valve made of animal tissue that is folded inside a stent, a mesh-like scaffolding similar to those used to help unclog heart arteries.
The U.S. studies thread the Edwards valve through a leg artery up to the heart, known as "percutaneous valve replacement."
Unlike with open-heart surgery, doctors do not stop the patient's heart. So the trickiest part is keeping regular blood flow from washing away the new valve before it is implanted.
Once the device is almost in place, doctors speed the heartbeat until normal pumping pauses for mere seconds - and quickly push the new valve inside the old one. Inflating a balloon widens the metal stent to the size of a quarter, lodging it into place and unfolding the new valve inside, which immediately funnels the resuming blood flow.
The experiments come with some significant risks.
Edwards temporarily halted the U.S. study last year after four of the first seven U.S. patients died. Initially, doctors threaded the valve up a leg vein, not an artery, a route that required tortuous turns inside the heart and sometimes damaged a second valve, O'Neill said. Twelve people have been implanted since the study restarted in December using the artery route considered easier and safer. All but one have survived and are faring well, researchers say.
[Last modified April 2, 2006, 01:25:16]
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