Use of a new clamp that uses radiofrequency energy for ablation rather than use of a scalpel makes it easier for surgeons to use the Cox-Maze procedure for atrial fibrillation and shortens the duration of the procedure, according to an article in the October issue of Annals of Surgery.

"Because of the devices, the procedure ? called the Cox-Maze procedure ? has gone from an operation that hardly anyone was doing to one that 80 to 90 percent of U.S. heart surgeons are now performing," said senior study author Ralph J. Damiano Jr., MD, the John Shoenberg Professor of Surgery and chief of cardiac surgery at the Washington University School of Medicine.

The Cox-Maze procedure has a greater than 90 percent cure rate for chronic atrial fibrillation.

Damiano and colleagues had previously played a vital role in the development and testing of radiofrequency devices for atrial fibrillation. The devices deliver high-energy radiofrequency waves to heart tissue and very quickly create scars, which replace most of the complex incisions required by the Cox-Maze procedure. The ablations disrupt the atrium’s abnormal electrical activity and normalize heart rhythm.

The research team found that surgeons needed to apply the devices for only a few seconds at a time to get effective ablation of the atrial wall, with no injury to surrounding tissue. The time needed for the procedure went from more than 90 minutes to about 30 minutes.

The modified Cox-Maze procedure eliminated atrial fibrillation in over 90 percent of patients in a recent study, a number that compares favorably with outcomes of the traditional cut-and-sew procedure. About three quarters of patients treated no longer need drugs to prevent abnormal heart rhythms or excessive blood clotting, Damiano said.

The Cox-Maze procedure is named for James Cox, MD, former director of Washington University's division of cardiothoracic surgery, who led the group that developed the procedure in 1987. The procedure ? which revolutionized treatment of atrial fibrillation ? calls for ten precisely placed incisions in the upper chambers of the heart. The incisions are then sewn up and eventually form scars in the atrial tissue.

The clamp-like jaws of the radiofrequency ablation devices deliver a thin, focused line of energy that heats and ablates the tissue. Ablation with the devices can replace all but two small incisions that would typically be made during a traditional Cox-Maze procedure.

"We've not only reduced the time needed for the procedure, we've made the procedure easier to perform," Damiano said. "In addition to eliminating most of the incisions, the radiofrequency ablation clamp removes the potential for error by monitoring when the lesion goes all the way through the tissue and automatically shutting the power off at that point."

By simplifying the Cox-Maze surgery, the method will make the procedure available to more patients. "This has made it possible to offer this curative operation to almost everyone coming for heart surgery who has chronic atrial fibrillation," Damiano said.

Other devices exist to create the Cox-Maze lesions ? these use microwaves, lasers, ultrasound or freezing. Damiano believes that the type of device used at the School of Medicine is superior because other types of devices may not be as consistent or as fast and can cause collateral damage to other areas of the heart.