Surgeons focusing on the mitral valve
March 1, 1999 4 minutes read
Surgeons focusing on the mitral valve
A change of heart for appropriate patients
A new surgical procedure may focus more attention on the role of the mitral valve in treating patients with heart failure.
The technique uses a ring to reinforce the valve so it can keep more blood from flowing backward into the left atrium. With a more efficient blood flow through the heart, patients may be able to regain cardiac performance over time.
For now, the procedure may help some patients in advanced heart failure live longer, even if they are not candidates for a transplant. Researchers hope that as they learn more about who is right for the procedure, they can use it to help their patients avoid the downward spiral of heart failure.
"We think this is a viable alternative," says Steven Bolling, MD, a cardiothoracic surgeon at the University of Michigan Medical Center in Ann Arbor.
He says when the heart enlarges during failure, its inner walls pull at the mitral valve. The pressure causes a problem, not in the organic makeup of the valve, but in the way it functions. Because it can’t stay closed when it should, regurgitation develops. Half of the blood that should be exiting the heart goes back into the atrium. This reverse flow becomes yet another obstacle to circulation the heart has to overcome.
Going in to replace the valve has meant robbing the heart of some pumping power. Because the patients were already compromised by heart failure, the loss was too much. Bolling says these patients just "have nothing more to give." Surgeons learned to leave the valve alone when the ejection fraction (EF) was low.
He says this procedure is different than traditional attempts to replace the mitral valve. Instead of replacing it, his procedure involves "scrunching it down" and keeping it in place so the heart won’t pull it open when it should stay closed. Better flow is restored without the loss in power.
"We are taking no function away from the heart," he says, which could make the procedure available to a broader spectrum of CHF patients.
"We have to change our thinking about these patients," he says, noting traditionally, patients qualified for surgery if they had an EF of at least 40%. He recently operated on a patient with an EF of 5. The patient came into the surgical program after living with CHF for years. Bolling says he wishes he could have performed the operation on her 10 years ago, before her quality of life declined to a point where she had to spend most of her day sitting in a chair.
It will take about two years to be more certain of the long-term benefits, Bolling says. Right after surgery, her EF probably was the same as before. But without the regurgitation, her heart has a better chance of regaining some lost ground.
Changing the way doctors think about these patients, he says, begins with understanding the relationship of valve and ventricle. Both elements are working together and should not be seen as separate parts. "We are not treating a ventricular problem with a valve solution," he says. "We are treating a ventricular problem with a ventricular solution."
Bolling says another conceptual change is accepting that damaged heart muscle, like other tissue, can heal if it can be rested. Finding a way to give the myocytes some down time is tough, however, because surrounding tissue continues to be worked on and has to keep pumping. Bolling says that helping blood flow efficiently through the failing heart can make tasks easier on the organ. Also, he notes left-ventricular assist devices (LVADs) may also find a role in helping the heart rest and heal. In this case, a combination therapy may be developed that uses the mitral valve procedure and an implanted LVAD. (For more information on LVADs, see CHF Disease Management, February 1999, p. 13.)
In the first phase of his study, Bolling says he operated on nearly 100 patients, and 70% to 80% were alive two years after surgery (compared to about 10% if the patient didn’t have the surgery). He reported his findings at the American Heart Association conference in November.
"He is getting some marvelous results," says Mehmet C. Oz, MD, a cardiothoracic surgeon at Columbia-Presbyterian Medical Center in New York City. Oz says his hospital has performed a dozen mitral valve procedures with similar outcomes.
Bolling notes the first stage of the study was to determine the feasibility of the surgery and if it should be studied against traditional drug therapy. That’s the next step, randomizing patients to medication and surgery.
"We need to identify patients who would do well," he notes. Being able to get to them for a quick surgical intervention may keep many from going on to develop serious disease requiring extensive treatment like transplantation.
"Could we go upstream and head them off at the pass?" Bolling asks. "The patient would then never go down the inevitable cascade of CHF."
The researcher notes that in the first study, patients were at advanced stages of the disease. The second part of the study, dubbed the PREMIUM trial, will include patients in New York Heart Association Class III disease. Because patients are not as sick with heart failure, Bolling says it may take longer to determine the benefit of the surgery. Unlike the first study, most patients would be expected to survive longer than a year without the intervention.
The PREMIUM trial also could hint at which patients may be at a stage of failure that cannot be reversed. "Which patients are these, where the heart muscle is too far gone?" Bolling asks. "We don’t know yet."
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