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COLUMBIA-PRESBYTERIAN MEDICAL CENTER
SINGLE SUTURE REPAIRS LEAKY HEART VALVES
Non-invasive version of operation under development
ORLANDO, FL, NOVEMBER 11, 1997 -- A novel technique for repairing leaky mitral valves, involving the placement of a single suture, is undergoing clinical trials at Columbia-Presbyterian Medical Center. It may soon be possible to perform the repair with minimally invasive techniques, eliminating the need for open-heart surgery and heart-lung bypass.
Two studies of the new "bow-tie" repair -- so named for the shape of the valve opening with the suture in place - were presented today at the annual meeting of the American Heart Association in Orlando, Fla.
The mitral valve controls the flow of blood from the left atrium into the left ventricle. When the valve's two leaflets do not completely close, as in a condition called mitral valve prolapse, there is backflow, or regurgitation, of blood. The heart then has to work harder to pump enough blood for the body, which can lead to heart damage.
Mitral valve prolapse is caused by a number of conditions, including genetic defects, infections, coronary artery disease (CAD), and myocardial infarction (MI). Prolapse is relatively common, occurring in approximately 7 percent of the population. Most cases are mild, and if the symptoms are bothersome, they can usually be controlled with medications. In more serious cases, the valve can be repaired with an annuloplasty, a surgical procedure in which a synthetic ring is placed around the valve rim (annulus). This promotes proper closure by decreasing the size of the valve opening. In some instances, the faulty valve must be replaced.
While these surgical repairs are effective, they do not necessarily address the root of the problem. According to Mehmet C. Oz, MD, Irving Assistant Professor of Surgery at Columbia-Presbyterian and a member of the research team, the underlying pathology is usually not in the valve itself but in the papillary muscles -- conical muscles that project from the ventricle's walls to tendinous chords (chordae) underneath the valve leaflets. When these tiny muscles fail, a common consequence of MI or CAD, the leaflets do not close properly. "So by putting a ring around the valve, you're fixing the problem, but not in a direct way," says Dr. Oz.
The bow-tie repair may be a better alternative. In this operation, a single suture is placed at or near the point at which the two leaflets first touch when the ventricle contracts. "To ensure proper closure of the valve, the tips of the leaflets first have to touch. That's the function of the suture. It's like a catch on a zipper - once contact is made, the rest of the valve closes right up," Dr. Oz explains. The repair also connects the unhealthy chordae to the healthy chordae, which then carry the burden of closing the valve tight.
The valve still opens -- on either side of the suture -- permitting normal blood flow.
Animal studies conducted at Columbia-Presbyterian show that the annuloplasty and the bow-tie repair produce comparable results. "This makes the bow-tie repair better," Dr. Oz believes. "First, it's easier to perform, and second, it allows the mitral valve annulus to dilate when you exercise, while the ring does not."
The technique was invented by an Italian surgeon and introduced in the United States by Dr. Oz. In a paper presented today, Dr. Oz reported that he and his team have performed this surgery in ten patients with mitral valve prolapse and severe CAD. In nine of the patients, the bow-tie repair was made after an annuloplasty did not achieve the desired results. In the tenth, an annuloplasty was not possible and the bow-tie was performed alone.
In all cases, mitral valve regurgitation was significantly reduced and the patients' overall condition improved. There were no fatalities and no complications related to the bow-tie suture.
The researchers anticipate that the bow-tie repair will initially be used as a secondary measure to annuloplasty. "As our experience evolves, we will begin to more frequently use the bow-tie repair alone," writes study leader Juan P. UmaÃ’a, MD, Postdoctoral Residency Fellow in the Department of Surgery, in an article to be published in the Annals of Thoracic Surgery.
The long-term effects of the repair are not known. However, the results of another study, conducted in Italy, show that the repair can last at least three years.
"Surgeons are understandably skeptical of the durability of single suture repair in an area of apparently high stress," writes Dr. UmaÃ’a. However, his studies show that the suture site experiences far less tension than anticipated.
The research team is now developing a way to make the valve repair without performing open-heart surgery and cardiopulmonary bypass. They have invented a transcatheter device that can be inserted into a leg artery and threaded up into the heart. At the end of the device is a tiny grasper than can hold the chordae together while a U-shaped clip is stapled around the ends of the leaflets. "It would be the first truly off-bypass valve operation," says Dr. Oz.
Approximately 30,000 people undergo mitral valve operations a year. About 20,000 of these would be candidates for a bow-tie operation. If a minimally invasive approach is developed, it could be applied to thousands more, including those who have leaky valves but are not sick enough to warrant a major operation.
Other members of the research team are Bijan Salehizadeh, BA, Joseph J. DeRose, MD, Tamanna Nahar, MD, Desmond Jordan, MD, Benjamin C. Sun, MD, Alan Lotvin, MD, Shunichi Homma, MD.
Contact: Karin Eskenazi, 212/305-5587
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