The Cox Maze procedure has been performed routinely since its first description in 1991. However, the degree of invasiveness precluded the widespread adoption of the Cox Maze procedure, limiting its use to only the most recalcitrant stand-alone AF cases and to concomitant AF ablation during cardiac surgery. Less invasive catheter ablation procedures for AF were introduced by Haissaguerre et al. in 1998, and although they have since become the procedure of choice for the interventional treatment of patients with paroxysmal AF (PAF), they have yielded less favorable results for persistent AF and long-standing persistent AF (see Chapter 31 ). Several “minimally invasive” surgical procedures were proposed to address this dilemma, but they proved to be little better than catheter ablation for PAF. In addition, while they were somewhat better than catheter ablation for non-PAF and were less invasive than a Cox Maze procedure, they were still far more invasive than catheter ablation. The dilemma of the success of interventional AF procedures being inversely related to their degree of invasiveness ultimately led to the development of thoracoscopic surgery for AF.
Development of Thoracoscopic Surgery for Atrial Fibrillation
In 2003, thoracoscopic surgery using a microwave energy source was described as a less invasive procedure than open surgery for performing pulmonary vein isolation (PVI). Unfortunately, this limited lesion set is adequate only for the isolation of AF triggers in the pulmonary veins (PVs). Nevertheless, the disappointing results of microwave PVIs for the overall treatment of patients with AF (i.e., all types of AF) were attributed to the use of microwave energy rather than to the fact that PVI is an inadequate operation for non-PAF. Thus, after this initial publication, microwave energy was abandoned and replaced by radiofrequency (RF) as the preferred new energy source for surgical AF ablation. Different minimally invasive and thoracoscopic surgical techniques were proposed for the surgical treatment of patients with AF, including bilateral video-assisted RF ablation and bilateral closed-chest RF ablation. , These attempts at AF ablation using only thoracoscopic surgical approaches were disappointing and as a result, the concept of a “hybrid procedure” was introduced in which thoracoscopic surgeons and interventional electrophysiologists joined forces to treat patients with AF. The incentive for such a procedure is to combine the best of the two worlds, epicardial RF surgical ablation and endocardial RF catheter ablation. Although the hybrid ablation procedures were promising and have proven to be useful, they were never directly compared with epicardial thoracoscopic ablation alone without follow-up endocardial catheter ablation. Our group observed early on that thoracoscopic epicardial RF ablation had similar success rates as hybrid procedures, so we persisted in this thoracoscopic-only approach for the treatment of stand-alone AF.
The FAST trial, which compared endocardial catheter ablation with closed-chest surgical RF isolation of the PVs, ganglionic plexus ablation, and left atrial appendage (LAA) closure in patients with persistent AF and PAF demonstrated that epicardial surgical ablation was superior to endocardial catheter ablation for rhythm control (66% vs 37%, respectively; P =.0022), although the procedural adverse event rate (mainly pneumothorax) was significantly higher for surgical ablation.
A multicenter cohort registry in 475 patients confirmed results for the thoracoscopic ablation of AF and showed an overall freedom from arrhythmia of 69% after a mean follow-up of almost 2 years. A systematic safety analysis in 558 patients confirmed the safety of thoracoscopic AF ablation and emphasized an interaction between the incidence of complications, age and gender, resulting in older female patients being more prone to complications than others. Another study in 222 patients showed a stroke rate of only 0.5% per 100 patient-years after LAA occlusion with postoperative oral anticoagulation in 43% of patients.
In 2016, the European Association for Cardio-Thoracic Surgery (EACTS)/European Society of Cardiology (ESC) guidelines for the management of AF awarded a Class 2A recommendation for the thoracoscopic ablation of AF. Despite this important validation, there remains some concern among patients and cardiologists regarding postoperative pain, which can lead to prolonged recovery. However, despite the natural increase in the number of patients with AF and demonstration of the safety and efficacy of thoracoscopic AF ablation, we did not experience the expected increase in the number of referrals for this therapy. This encouraged surgeons to find even less invasive ways to treat patients with AF. In 2020 and 2021, surgeons from the Netherlands introduced the unilateral right-chest and unilateral left-chest approaches for thoracoscopic ablation that limited the postoperative pain to one side. , This experience emphasizes the importance of reducing postoperative pain as much as possible and the lowest possible level of pain seems to have been reached with these unilateral approaches. In our current technique, only two 5-mm and one 1-mm incisions are required to do the entire operation. However, no matter how minimally invasive we can make surgery, it will always be more invasive than catheter ablation, which requires only the puncture of a vein in the groin. On the contrary, catheter ablation must compete with the efficacy of surgical ablation, which remains the gold standard for the interventional treatment of patients with AF. Although catheter-based technology has evolved significantly over the years, any energy delivered through a catheter will always be from a single unipolar device that targets the tissue from only one side while being guided by fluoroscopy rather than direct vision. Therefore, achieving reliably contiguous and uniformly transmural lesions will remain a major challenge for the catheter ablation of AF.
Current Surgical Technique
The 2020 ESC/EACTS guidelines for the management of AF state that there is no supporting evidence for the use of catheters, which are unipolar, to create atrial lines other than those around the PVs. Currently, bipolar RF clamps are used to isolate the PVs, and unipolar radiofrequency (RF) pens are the only devices available to create additional atrial lesions from the epicardium. However, as in catheter ablation, it is difficult to create reliably transmural and contiguous linear lesions with unipolar RF pen devices. In 2022, we described a unilateral right-chest approach in which the entire left atrial box lesion was created with bipolar RF clamps only, thereby ameliorating the need for unipolar devices and substantially reducing the risk for incomplete lesions and treatment failure. The major challenge to overcome during the development of this off-pump approach was to make sure that cardiac output and adequate blood pressure are maintained throughout the ablation. This means that all four PVs cannot be clamped simultaneously. The left PVs are first isolated as described in the right sided unilateral approach ( Fig. 32.1 ). Next, the roof and floor lesions are created in two stages. First, the two right PVs and the left inferior PV are clamped simultaneously and ablated, leaving the left superior PV open ( Fig. 32.2 ). Then the two right PVs and the left superior PV are clamped and ablated, leaving the left inferior PV open ( Fig. 32.3 ). This completes the box lesion isolating all four PVs and the intervening posterior left atrial wall ( Fig. 32.4 ).
The left pulmonary veins are isolated with a bipolar radiofrequency clamp (dark blue circle).
