Radial approach: A new concept in surgical treatment for atrial fibrillation. II. Electrophysiologic effects and atrial contribution to ventricular filling

Background. In a previous study the atrial incisions that follow the concept of the radial approach were designed according to the activation sequence during sinus rhythm and the atrial coronary artery anatomy in normal dogs. The purpose of the present study was to determine whether the radial approach provides a more physiologic activation sequence and atrial transport function than the maze procedure. Methods. Ten dogs that had undergone the radial approach (n = 5) or the maze procedure (n = 5) were studied 6 weeks postoperatively. Sinus node function and inducibility of atrial fibrillation were examined before and after operation. The atria were mapped endocardially with 212 electrodes, and atrial activation sequences during sinus rhythm and right atrial pacing were examined. Atrial transport function was assessed by transepicardial Doppler echocardiography. Results. No dogs developed sinus node dysfunction postoperatively. Both the radial approach and the maze procedure equally prevented sustained atrial fibrillation. The atrial activation sequence was more synchronous after the radial approach than after the maze procedure. There was no electrically isolated region after the radial approach. The total activation time of the left atrium was significantly shorter after the radial approach than after the maze procedure (53.6 ± 9.8 versus 70.5 ± 9.6 ms, p < 0.05). The ratio of peak flow velocity of the E wave to the A wave (peak E/A) of the transmittal Doppler flow was significantly smaller after the radial approach than after the maze procedure (1.7 ± 0.4 versus 3.5 ± 1.7, p < 0.05). The atrial filling fraction of the transmitral Doppler flow was significantly larger after the radial approach than after the maze procedure (29.9% ± 7.3% versus 14.8% ± 5.0%, p < 0.01). There was no significant difference in peak E/A and atrial filling fraction of the transtricuspid Doppler flow between the two procedures. Conclusions. The radial approach provides a more synchronous activation sequence and atrial transport function, and thus may represent a more physiologic alternative to the maze procedure as a surgical treatment for atrial fibrillation.