Small study shows new mitral valve ring fixes two problems at once
SAN FRANCISCO -- A new heart valve ring appears to help congestive heart failure patients regain lost heart function, reversing the disease's effects on heart structure in two ways and easing their disabling symptoms, researchers reported here today at the 85th Annual Meeting of the American Association for Thoracic Surgery.
A prospective study of the first 25 patients who had surgery to install the ring shows that it reduced the leakage of blood back through the mitral valve, which leads to the heart's main pumping chamber. But it also changed the shape of that chamber, called the left ventricle, helping its muscular walls contract and pump blood better.
All 25 patients had mitral valve regurgitation (leakage) as a result of distorted left ventricles, and were experiencing severe symptoms, before having surgery to install the ring. All experienced great improvement in their symptoms, and lived at least a month after the operation. All but two were still alive six months after surgery.
The ring was co-invented by Steven Bolling, M.D., the University of Michigan Cardiovascular Center cardiac surgeon who presented the results on behalf of the research team, and by Italian cardiac surgeon Ottavio Alfieri of the St. Raffaele Hospital in Milan. The ring is made of titanium and silicone rubber.
The technology was licensed to Edwards Lifesciences Corporation for development and commercialization, and will be marketed as the GeoForm mitral valve repair ring. Both the co-inventors and the U-M stand to benefit financially from the device's sale.
The GeoForm ring has been approved by the U.S. Food and Drug Administration for use in tightening leaky mitral valves. But the new data are the first indication that it also re-shapes the left ventricle, which often becomes distended and misshapen after a heart attack or infection attacks the heart muscle. Nearly 5 million Americans have congestive heart failure, and the number is expected to climb.
"Congestive heart failure is a ventricular disease, but previous efforts to reshape the ventricle by repairing the mitral valve have been hit-or-miss," says Bolling, who heads the U-M's Mitral Valve Clinic and is a professor of surgery at the U-M Medical School. "This ring's special three-dimensional shape makes it easier for the surgeon to pull the heart muscle up in a way that forces the left ventricle to remodel whether it wants to or not, and returns the heart to a pointy, or ellipsoid, shape from a rounded shape." He likens the effect to turning a basketball shape into a football shape.
Bolling notes that many surgeons are now repairing the mitral valves of heart failure patients, to help reduce the regurgitation of blood back into the lungs. "For patients having mitral valve repair, this ring may offer added advantage," he says.
The encouraging new data, he notes, are from severely ill patients. Eventually, he hopes, patients in earlier stages of heart failure might be able to have surgery to slow their heart's decline.
The new findings were made in patients treated at the U-M Cardiovascular Center, through a study led by U-M cardiologist David S. Bach, M.D. Bolling performed all 10 operations, but the cases were all reviewed by Bach. A continued GeoForm study, also led by Bach and involving more patients, is now under way, and other centers are beginning to explore the use of the GeoForm ring in their heart failure patients. Patients interested in learning more about mitral valve surgery options at the U-M may call 734-936-1900.
The GeoForm ring may complement another device now under study to help failing hearts continue to pump, Bolling says. That device, called the Acorn CorCap Cardiac Support Device, is a mesh sac that wraps around the heart and holds the enlarged left ventricle in.
Bolling is part of a team that presented results at the AATS meeting from patients who had mitral valve surgery, some of whom were randomized to receive an Acorn CorCap at the same time. Some patients had their mitral valves repaired, while others received a total artificial valve.
That study was the first to show in a multi-center trial that mitral valve surgery can be performed safely even in patients with advanced heart failure, and that it results in very low rates of death up to two years after surgery. The study also shows that the Acorn device helped the ventricular remodeling that happened in some patients who had typical valve repair or replacement.
The Geoform ring, and the Acorn device, Bolling says, should also give heart failure patients a viable option when heart donor shortages limit the opportunity for a heart transplant, which is currently the standard treatment for patients with severe congestive heart failure associated with end-stage heart disease.
According to the American Heart Association, approximately one in five people aged 40 years and older may congestive heart failure in their lifetime. Many CHF patients develop cardiomyopathy, a weakening of the heart muscle that distorts and enlarges the left ventricle, inhibiting the mitral valve's flap-like leaflets from properly closing and causing blood to flow backward through the heart.
Failure to adequately reverse the onset of this condition, known as mitral valve regurgitation, can further lead to even greater mitral valve regurgitation and an increased likelihood of heart failure, according to a 1998 study published by Bolling and his colleagues in the Journal of Thoracic and Cardiovascular Surgery.
The introduction of Edwards' new GeoForm mitral valve repair ring comes on the heels of a recent study published in the New England Journal of Medicine, which found that people who had severely leaky mitral heart valves but no symptoms were five times more likely to die of a heart problem, and six times more likely to have heart failure or some other serious cardiac problem. Lead researcher Maurice Enriquez-Sarano, M.D., professor of medicine at the Mayo Clinic and director of the Mayo Clinic's valvular heart disease clinic, estimates that of the approximately 2.7 million Americans who have notable mitral valve leakage, about 600,000 are probable candidates for early intervention.
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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