Catheter techniques are expanding into new territory, successfully aiding in the replacement of narrowed, calcified aortic valves in patients too sick to withstand open-chest surgery.
According to a study reported at the 30th Annual Scientific Sessions of the Society for Cardiovascular Angiography and Interventions (SCAI), May 9?12, 2007, in Orlando, FL, patients who were treated with the CoreValve Revalving System (CoreValve, Irvine, CA) experienced improvements in both the size of the aortic valve and in the severity of heart failure.
To evaluate the CoreValve system, Anita Asgar, M.D., and her colleagues at Montreal Heart Institute recruited 17 elderly patients with a severely narrowed aortic valve, all of whom had been turned down for surgery because of other health problems. In severe narrowing, or stenosis, of the aortic valve, the heart has difficulty pumping blood from the left ventricle to the rest of the body. The result is a back-up of fluid into the lungs and severe shortness of breath with even minimal activity.
With the CoreValve system, aortic valve replacement is performed by threading a special delivery catheter through the femoral artery in the groin and into the aorta in a direction opposite, or retrograde, to the normal flow of blood. Once the catheter is properly positioned in the opening of the aortic valve, it is pulled back to release the CoreValve, a self-expanding stent-like frame with the new tissue valve attached to its core. As it expands, the CoreValve covers the diseased natural valve leaflets.
During the procedure, the patients were placed on a bypass pump for an average of 30?40 minutes to minimize blood flow through the aorta and ease placement of the replacement valve.
All 17 patients survived the procedure. One patient died 5 days later from stroke. Five additional patients died after discharge from the hospital from health problems unrelated to the replacement valve. Follow-up in the 11 survivors showed that the average aortic valve area more than doubled, on average, following the procedure. In addition, the severity of heart failure significantly improved, as gauged by both B-type natriuretic peptide (NT-BNP), a protein produced by the ventricles of the heart during heart failure, and New York Heart Association (NHYA) classification. After the procedure, patients were ranked in NYHA class II, on average, suggesting most were able to engage in a moderate level of activity before becoming short of breath.