The Cox maze III procedure has equivalent operative risk and long-term efficacy in patients undergoing both lone operations and concomitant procedures. The Cox maze III procedure remains the standard against which alternative procedures for atrial fibrillation must be judged.

ObjectiveThe authors analyzed the clinical results during the first 81k years' experience with the Maze procedure for the surgical treatment of atrial fibrillation. Summary Background DataAtrial fibrillation occurs in 0.4% to 2% of the general population and in approximately 10% of patients older than 60 years of age. ft is associated with significant morbidity and mortality. The irregular heartbeat causes discomfort, the loss of synchronous atroventrcular contraction compromises hemodynamics, and the stasis of blood flow increases the vulnerability to thromboembolism. Methods ResultsNinety-three percent of all patients were arrhythmia free without any antiarrhythmic medication. Of the remaining patients with arrhythmia recurrence, all were converted to sinus rhythm with medical therapy. All patients were documented to have atrial transport function by either direct visualization, transesophageal echocardiography, or atrioventricular versus ventricular pacing at the same rate. Ninety-eight percent had documented right atrial function, and 94% had left atrial function. Of the 107 patients in this series who were documented to have a normal sinus node preoperatively, only 1 patient required a permanent pacemaker. ConclusionThe Maze procedure is an effective treatment for medically refractory atrial fibrillation in properly selected patients. 267

Atrial depolarization was analyzed in 14 patients with the Wolff-Parkinson-White syndrome undergoing surgery to ablate accessory atrioventricular pathways associated with tachyarrhythmias. Bipolar potentials were recorded simultaneously from 156 atrial epicardial electrodes arranged in three templates to fit the anterior and posterior aspects of both atria. Spontaneous or sinus rhythms were recorded, as were atrial escape rhythms after overdrive pacing at rates of 150 and 200 beats/min. Atrial activation maps revealed different patterns of impulse initiation varying from typical unifocal sinus node impulse origin, unifocal extranodal impulse origin, and multicentric impulse origin from two to four widely distributed atrial pacemaker sites. In subjects demonstrating only unifocal impulse origin during control or sinus rhythm, other widely divergent pacemaker sites were recorded in other maps during subsequent rhythms. In addition to sites located at the upper superior vena cava-right atrium junction, pacemakers also dominated at sites anterior and inferior to the sinus node region during both control and escape depolarizations. Most of the subjects were found to have two or more pacemaker sites when maps of all control and postpacing conditions were analyzed. The right atrial pacemaker region encompassed a zone of 7.5 X 1.5 cm centered about the long axis of the sulcus terminalis posteriorly and the precaval band anteriorly. An unexpected finding was the participation of left atrial escape pacemakers. The functional behavior of both the control and escape pacemakers, as assessed by sinus node recovery time, was normal, indicating physiologic operation of the extranodal sites as part of an overall system of distributed pacemakers involved in the control of rate. Although functional assessment was limited in these initial patient studies, correspondence with similar observations in extensive previous canine studies supports the concept of a widely distributed atrial pacemaker complex in man.

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