American Heart Association meeting report:
DALLAS, Nov. 9 -- A new surgical procedure may help extend and improve the lives of people with severe congestive heart failure (CHF), according to research presented today at the American Heart Association's 71st Scientific Sessions. The operation -- surgically repairing the mitral valve of the heart -- may prove to be an alternative to heart transplantation in some people with CHF, says cardiovascular surgeon Steven F. Bolling, M.D., the first to propose this operation as a way to improve heart functioning in people with severe CHF. The mitral valve controls blood flow between the upper and lower chambers of the left side of the heart.
The one-year and two-year survival rates for the CHF patients in the study who underwent mitral valve reconstruction has been 80 percent and 70 percent respectively, says Bolling, professor of cardiac surgery at the University of Michigan, Ann Arbor. If they had not undergone the surgery, he adds, their one-year survival rate would have been 20 percent at best.
In congestive heart failure, the only form of heart disease increasing in the population, the mitral valve can weaken and fail to close adequately when the heart expands. When the mitral valve allows blood to flow backward into the atrium, the upper chamber of the heart, the heart must work even harder to pump blood throughout the body.
"An inefficient mitral valve adds even more pressure to a heart already damaged by congestive heart failure and exacerbates an already serious condition," says Bolling. In addition, blood that has pooled in the atrium can form blood clots that can obstruct the blood vessels to the brain, resulting in a stroke. When Bolling repairs the mitral valve, he surgically reinforces the thin flaps of muscle tissue, called leaflets, which act as gates allowing blood to flow from the left atrium to the left ventricle. The reinforcement involves surgically inserting a flexible "annuloplasty" ring at the valve opening. By using a relatively small size ring, Bolling "over-corrects" the mitral valve. The "over correction" may be important to the effectiveness of the procedure, he says.
Bolling stresses that the mitral valve defect that occurs in CHF is not an isolated condition. "In the past, the mitral valve has been incorrectly regarded as functioning independently from the rest of the heart," he explains. "This is not the case. All of the heart's components must work in concert together as one muscle. This is a new paradigm for thinking about the mitral valve and CHF."
During the past four years, Bolling has surgically corrected the mitral valves of almost 100 patients, 33 to 79 years old, at the University of Michigan hospitals. Prior to the surgery, patients were treated with drug therapy. In the one-year period before their operations, these patients had an average of nine CHF-related hospitalizations.
The average time for follow-up after surgery for each patient has been over 3.5 years. The average hospital stay for the patients was nine days. None of the participants died during hospitalization, but one patient died during surgery, says Bolling.
Bolling reports that after surgery, the patients' exercise tolerance improved and their heart size decreased. Improvement also occurred in the ability of their hearts to pump blood -- as indicated by the ejection fraction measurement increasing from an average of 16 percent before surgery to 26 percent after surgery. An ejection fraction is the percent of blood in the left ventricle that is pumped out with each beat. A normal ejection fraction is about 70 percent.
Before surgery, the severity of their congestive heart failure was characterized as Class III or Class IV, the highest categories. The patients are now classified as Class II and continue to receive drug therapy.
Bolling says people with such severe CHF typically have been regarded as "inoperable" with their only hope of survival being a heart transplant. "Because of the shortage of donor organs, heart transplant surgery is not a realistic treatment for most of these patients," he points out. Therefore, Bolling and other cardiovascular surgeons have been searching for other approaches to improve and prolong these patients' lives. Removing part of the heart muscle in a partial left ventriculectomy -- often called the "Batista" surgical procedure -- has been proposed as one approach.
Surgically reconstructing the mitral valve of these patients is another approach, says Bolling. "In addition to improving heart function, this surgery may enable heart tissue damaged by congestive heart failure to rest and repair itself and to remodel cells so that they can resume their normal shape," he adds. In CHF, heart cells typically become abnormally elongated or stretched. The study was recently extended to include 140 additional patients with Class III CHF. Bolling says this next phase of the study investigates whether earlier intervention might delay or even prevent the progression of the disease to the terminal Class IV stage.
Bolling and his colleagues have twice published the results of their research with this surgery in The Journal of Thoracic and Cardiovascular Surgery. The most recent paper, reporting on 48 patients, was published in February 1998.