Intraoperative epicardial electrophysiologic mapping and isolation of autonomic ganglionic plexi

Background. Autonomic ganglionic plexi (GPs) have been implicated as triggers in lone atrial fibrillation (AF). The purpose of this study was to describe the technique and results of epicardial electrophysiologic mapping and the early effects of GP isolation. Methods. Intraoperative epicardial electrophysiologic mapping was performed on 41 consecutive patients during a stand-alone minimally invasive operation for AF. A map labeling anatomic locations was developed to describe the findings. Intraoperative high-frequency stimulation (800/minute, 12 to 16 mA, pulse duration 9.9 ms) was performed using a standard quadripolar catheter placed directly on the epicardium. Locations where stimulation resulted in ventricular slowing with doubling of the electrocardiographic R-R interval were defined as active GPs. These areas were mapped and described. After dry bipolar radiofrequency isolation, the sites were again stimulated to assess isolation. Results. Forty-one patients ( mean age of 60.2 years, 31 males) underwent operation for AF ( 28 intermittent AF, 13 chronic). Active GPs were identified in all patients ( 24 bilateral, 17 unilateral). There was a mean of 5.0 GPs on the right and 2.7 on the left. More than 50% of patients had active GPs along the interatrial groove on the right and along the ligament of Marshall. All sites were inactive after radiofrequency isolation. Six-month follow-up is available for 15 patients, with 14 patients free of AF. Conclusions. Autonomic GPs can be routinely identified during AF surgery utilizing high-frequency stimulation. The GPs are clustered around the interatrial groove and the ligament of Marshall, and the cardiac response to GP stimulation can be eliminated with bipolar radiofrequency isolation. The addition of GP isolation to bilateral pulmonary vein isolation may increase freedom from AF. (c) 2007 by The Society of Thoracic Surgeons.