The Cox-maze procedure was developed and first performed at Washington University in 1987. The final version of that procedure, called the Cox-maze III, has now been carried out on 250 patients at that institution since 1988, with more than 1500 patient-years of follow-up. Although the procedure has excellent long-term efficacy in curing AF, it has not been widely practiced because of technical challenges. As the investigators note, the surgery is complex, requiring prolonged periods of cardiopulmonary bypass and multiple technically difficult incisions to be made in both the right and left atrium.

To simplify the problems with the traditional Cox-maze III procedure, researchers have been evaluating strategies to modify the surgery, including replacing the surgical incisions with linear lines of ablation made by various energy sources.

"Elimination of the extensive cutting and sewing needed to make the atrial incisions of the Cox-maze procedure gives these new operations the potential to simplify the procedure and decrease the time of surgery," write first author Dr Sydney Gaynor (Washington University School of Medicine) et al. "The hope is that this will reduce morbidity, encourage referrals, and speed the adoption of this operation by surgeons."

The hope is that this will reduce morbidity, encourage referrals, and speed the adoption of this operation by surgeons.

From January 2002 to October 2003, 40 consecutive patients underwent the modified procedure using bipolar radiofrequency ablation to isolate the pulmonary vein. The ablation device consists of two 1-mm electrodes embedded in the jaws of a clamp that can be placed around target tissue. The resulting lesions are thin and discrete, note investigators, eliminating the possibility of collateral tissue damage.

In the modified procedure, more than half of the Cox-maze incisions were replaced with radiofrequency ablation lines, and the device was used to individually isolate the right and left pulmonary veins. As opposed to the traditional maze procedure, investigators preserved the right atrial appendage. Two of the right atrial lesions were replaced with bipolar radiofrequency ablation lines.

Of the 40 patients, 25 had paroxysmal AF and 15 had persistent AF. In every procedure, the left and right pulmonary veins were isolateddocumented by pacing before and after the procedurewith both veins undergoing, on average, 3.0 radiofrequency applications.

There was no operative mortality or postoperative strokes. Follow-up MRI in eight patients four to six weeks after the procedure showed no evidence of pulmonary vein stenosis in any patient. Atrial contractility was present in every patient.

The mean crossclamp times were 54 minutes for the modified lone Cox-maze III procedure and 99 minutes for the maze procedure plus cardiac surgery. Investigators note that these times were significantly shorter than the traditional Cox-maze procedures93 minutes for the lone maze procedure and 122 minutes for the concomitant procedureperformed at their institution.

"The use of this device decreased mean crossclamp time in both lone CMP [Cox-maze procedure] and concomitant CMP groups by more than 30 minutes," report Gaynor and colleagues, adding that isolation of the pulmonary veins can be performed on the beating heart before crossclamping. They note, however, that the procedural-time comparison is with a historical cohort performed by a different surgeon, making direct comparisons problematic.

The authors caution that the study is limited in that it represents a small number of patients with short follow-up. They add that pulmonary vein stenosis was evaluated at one month, which may be too short a time to pick up on the complication, and that careful long-term observations will be needed to demonstrate the efficacy of the new modification to the maze procedure.