Background: Ablation of the left atrium to isolate the pulmonary veins has been shown to interrupt electrical foci that may induce atrial fibrillation. This study evaluated the feasibility of performing a minimally invasive left atrial isolation on a beating heart using the da Vinci Robotic Surgical System and a flexible microwave probe (Flex 10 by AFx, Inc., Fremont, CA, USA), and the reliability of exit block pacing to confirm transmurality of the lesions created.
Methods: On six canines, the Flex 10 probe was passed around the left atrium posterior to the superior vena cava, through the transverse sinus, and back through the oblique sinus via a right-chest-only approach using the da Vinci Robotic Surgical System. Prior to ablation, pacing outside the atrial cuff was confirmed. Ablation was then carried out on the beating heart and repeated (as needed) until electrical isolation was demonstrated by exit block pacing. Probe position was confirmed at the completion of the procedure via sternotomy. Analysis included acute histologic and gross examination of the targeted area.
Results: There was no significant difference (p = 0.110) in procedure time, although it decreased 39.6% from the first three cases to the last three cases. Electrical evidence of electrical left atrial isolation was achieved in all subjects. Acute histologic examination confirmed transmurality inconsistently. Additionally, in two animals, the Flex 10 probe was found to be anterior to the left atrial appendage. All animals survived the procedure.
Conclusion: A minimally invasive left atrial isolation procedure using monopolar microwave energy with the da Vinci Robotic Surgical System is simple and feasible. However, despite creating an electrical block, transmurality was not demonstrated consistently and further confirmation of catheter positioning is necessary during a right-chest-only approach.