Surgical Ablation of Atrial Fibrillation

Abstract

The Cox-maze procedure for the restoration of normal sinus rhythm, initially developed by Dr. James Cox, underwent several iterations over the years. The main concept consists of creating a series of transmural lesions in the right and left atria that disrupt re-entrant circuits responsible for propagating the abnormal atrial fibrillation rhythm. The left atrial appendage is excluded as a component of the Maze procedure. For the first three iterations of the Cox- maze procedure, these lesions were performed using a surgical cut-and-sew approach that ensured transmurality. The Cox-Maze IV is the most currently accepted iteration. It achieves the same lesion set of the Cox- maze III but uses alternative energy sources to create the transmural lesions, potentially in a minimally invasive approach on the beating heart. High-frequency ultrasound, microwave, and laser energy have all been used with varying success in the past. Today, bipolar radiofrequency heat or cryotherapy cooling are the most accepted sources for creating linear lesions with consistent safety and transmurality. The robust and reliable nature of these energy delivery methods has yielded a success rate reaching 90% freedom from atrial fibrillation at 12 months. Such approaches offer a significant long-term advantage over catheter-based ablation, especially in patients having longstanding, persistent atrial fibrillation with characteristics such as dilated left atrial dimensions, poor ejection fraction, and failed catheter ablation. Based on these improved results, there currently is significant interest in developing a hybrid ablation strategy that incorporates the superior transmural robust lesions of surgical ablation, the reliable stroke prevention potential of epicardial left atrial appendage exclusion, and sophisticated mapping and confirmatory catheter-based ablation technology. Such a minimally invasive hybrid strategy for ablation may lead to the development of multidisciplinary "Afib teams" to obtain optimal long-term sinus rhythm control. This article provides an overview of current surgical strategies for patients with atrial fibrillation and addresses the two main goals in its management.

Keywords: atrial fibrillation; maze procedure; surgical ablation.

Basel Ramlawi, M.D.

Walid K. Abu Saleh, M.D.

Figure 1.

Proposed simplified strategy for management of persistent and paroxysmal atrial fibrillation. CHADS₂ score of 1 is controversial whether anticoagulation is necessary. The CHA₂DS₂VASc is used by others. Renal failure not included in either system is also considered a risk factor for stroke and systemic thromboembolism. **For all atrial fibrillation patients undergoing cardiac surgery. Discontinuation of anticoagulation after LAA exclusion is still controversial, but is reasonable if LAA complete exclusion is confirmed at 3 months after surgery and/or patient is at high-risk for anticoagulation. ***MIS epicardial LAA exclusion preferred when patient can tolerate general surgery, not a redo stemotomy/left thoracotomy and with good pulmonary functions. MIS: minimally invasive surgery; AVN: atrioventricular node; STE: systemic thromboembolism; INR: international normalized ratio; TTR: time in therapeutic range; LAA: left atrial appendage.

Figure 2.

Complete set of atrial lesions as done in the Cox-maze IV procedure.

Figure 3.

Schematic drawing of ablation lines performed in the LA during a hybrid approach. Epicardial lines: 1, pulmonary vein isolation; 2, roof line; 3, inferior line; 4, line between the superior line and the left fibrous trigone; 5, connecting the line from the superior PV and the LAA; 6, line from the right inferior PV to the CS; 7, superior vena cava isolation; 8, intercaval line. Endocardial lines: a, mitral isthmus line; b, cavotricuspid line; *, ablation of complex fractionated atrial electrogram (CFAE). LA, left atrial; PV, pulmonary vein; LAA, LA appendage; CS, coronary sinus; MV, mitral valve. (Reproduced with permission from Gelsomino S, Van Breugel HN, Pison L, et al. Hybrid thoracoscopic and transvenous catheter ablation of atrial fibrillation. Eur J Cardiothorac Surg 2014; 45:401–7).