Current treatments for atrial fibrillation (AF) include medications, electrical cadioversion (used to restore normal heart rhythm with an electric shock), radiofrequency ablation, surgery and atrial pacemakers. Some of these approaches are complex and time-consuming, therefore a new device has been developed that radically reduces surgery time as well as simplifies complex procedures used to treat persistent AF.
Heart surgeons at Washington University School of Medicine in St Louis, MO, have simplified a common surgical procedure used to treat AF, termed Cox-maze, in which they hope will be made available to more patients. The new procedure, Cox-maze IV could potentially replace the older 'cut and sew' Cox-maze III, in which ten precisely placed incisions in the heart muscle created a 'maze' to redirect errant electrical impulses.
In a recent study published in the February issue of Journal of Thoracic and Cardiovascular Surgery,
Dr Ralph Damiano, the John Shoenberg professor of Surgery and chief of cardiac surgery at the School of Medicine and a cardiac surgeon at Barnes-Jewish Hospital, and colleagues compared surgical outcomes of patients undergoing the Cox-maze III procedure versus those of patients undergoing the Cox-maze IV procedure by using propensity analysis. According to the researchers, from April 1992 to July 2005, 242 patients underwent the Cox-maze procedure. Of these, 154 patients had the Cox-maze III procedure, and 88 had the Cox-maze IV procedure.
"Using the significant regression coefficients, each patient's propensity score was calculated, allowing selectively matched subgroups of 58 patients each," they reported. Late follow-up was available for 112 (97%) patients, and freedom from AF recurrence and survival was calculated at one year by using Kaplan-Meier analysis.
The new device is a clamp-like instrument that heats heart tissue using radiofrequency energy. By grasping areas of the heart within the jaws of the device, surgeons can create lines of ablation on the heart muscle. In the older Cox-maze III procedure, the lines of ablation were made by cutting the heart muscle, sewing the incisions back together and letting a scar form.
The results demonstrated that the use of bipolar radiofrequency ablation has simplified the Cox-maze procedure, making it applicable to virtually all patients with AF undergoing concomitant cardiac surgery.
"This technology has made the Cox-maze procedure much easier and quicker to perform," says Damiano. "Instead of reserving the Cox-maze procedure for a select group of patients, we would urge use of this device for virtually all patients who have AF and are scheduled for other cardiac surgery."
"The older Cox-maze procedure was a very complicated operation, and very few surgeons were willing to do it," said Damiano. "So we started working on new technology and helped develop an effective ablation device that simplifies the procedure. Not only is Cox-maze IV shorter, but with the new device the procedure is also much safer because there's a much lower risk of bleeding."
Damiano believes that their most recent study of Cox-maze IV is unique because the surgeons carefully matched the age, sex and cardiac conditions of a group of patients who underwent Cox-maze III in the past with patients undergoing Cox-maze IV. "This is the first documentation of the effectiveness of the ablation devices compared to the incisions of the Cox-maze III," Damiano says. "This operation is very effective, and we now use the Cox-maze IV technique exclusively."