The minimally invasive standalone maze technique is a key nonpharmacologic therapeutic option in the modern era. According to Cox, the ideal surgery for AF “would be performed via a minimally invasive incision (or endoscopically or robotically), off bypass, in less than 1 hour, with hospital discharge planned for the next morning” (37
). Surgeons have strived to meet this objective, attempting to reap the efficacy benefits of the Cox Maze III technique while preventing the related morbidity and complexity. The minimally invasive standalone maze procedure includes left atrial appendage (LAA) exclusion, PVI, and ablation of the ganglionic plexuses (GPs) and the ligament of Marshall, all combined into one surgery (38
). For nonparoxysmal patients, linear lesions can also be added (39
). This procedure can decrease the risk of emboli, enable extensive mapping of the GPs and ligament of Marshall, and help prevent catheter ablation–related adverse events. However, compared with medical therapy, minimal access surgery does have some risks: lengthier hospitalizations and recovery periods, the required use of general anesthesia, greater patient discomfort, and the bleeding risk associated with LAA excision.
CryoMaze is one variety of such minimal-access AF ablation. Although called minimal access, it does utilize cardio-pulmonary bypass with retrograde perfusion and employ a groin incision for cardiopulmonary bypass as well as a minimal-access mini-thoracotomy incision, as described by Gammie and colleagues (40
). Between July 2002 and November 2005, 119 patients underwent CryoMaze. Thirty-three patients had pre-operative intermittent AF, and 28 (85%) were in NSR at late follow-up (>3 years). However, for the 58 patients with continuous AF, the results were less impressive, with 27 patients (47%) being in NSR (P
< 0.0001). The overall rate of freedom from AF was 60% at late follow-up. There was one perioperative stroke, which was entirely resolved within 1 month, and there were no late strokes. Another study was conducted using CryoMaze, this time with the multiple–purse-string technique, wherein atriotomies are avoided via the placement of sutures on the left and right epicardial surfaces (41
). A total of 12 patients underwent this procedure, either combined with CABG (n = 9), combined with aortic valve replacement (n = 2), or as a standalone surgery (n = 1). Five additional patients required a small left atrial atriotomy to ensure that the mitral valve isthmus lesion was complete. There were no cerebrovascular accidents/transient ischemic attacks or perioperative mortalities. There was 1 late death, and 91% of the patients were free of AF or flutter at a mean follow-up of 13 ± 6 months.
Also influencing the progress of surgical therapy for patients with AF is video-assisted technology. Wolf et al pioneered this innovation, conducting a video-assisted bilateral PVI and LAA exclusion via minithoracotomy in 27 patients with AF (18 with paroxysmal AF, 4 with persistent AF, and 5 with permanent AF) whose condition was intolerant to or refractory to pharmacologic interventions (42
). At a follow-up of >3 months, 21 patients (91.3%) had freedom from AF. There were no deaths or conversions to sternotomy or full thoracotomy. Yilmaz et al performed a study of video-assisted totally thorascopic PVI with GP ablation and LAA amputation, for which data on the first 30 patients are available (43
). With a mean follow-up of 11.6 months, 77% of the patients were free of AF. The mean operation time was 137.4 ± 24.7 minutes, and the mean length of hospital stay was 5.1 ± 1.8 days. No cerebrovascular accidents, pacemaker placements, or deaths occurred. Additionally, Ed-gerton and colleagues conducted a study in which video-assisted technology was utilized for PVI and partial autonomic denervation for 74 patients with AF (44
). At a follow-up of 6 months, overall, 92.9% of the patients were in NSR as determined by an electrocardiogram, and 74.2% of the patients with longer-term observation had no indications of AF. By AF type, 56.5% of the patients with persistent/longstanding persistent (LSP) AF and 83.7% of the patients with paroxysmal AF were free of detectable AF (AF episodes >15 seconds). Partial autonomic denervation combined with PVI is proposed to be an effective and safe surgical option for patients with AF.
Video-assisted technology has played a key role in another recent study of a novel minimally invasive surgical method: the totally thorascopic video-assisted PVI, GP ablation, and LAA exclusion, with perioperative electrophysiologic confirmation (45
). Krul et al utilized bipolar radiofrequency to treat 31 patients (16 with paroxysmal AF, 13 with persistent AF, and 2 with LSP AF). Eighty-six percent of the patients were free of AF recurrence, atrial flutter, and atrial tachycardia and were not using antiarrhythmic agents at 1-year follow-up. No deaths or thromboembolic events occurred. Therefore, this procedure could be a reliable, cost-effective new therapeutic choice for surgeons treating AF.
Pulmonary vein isolation alone, although effective for paroxysmal AF, is not sufficient treatment for patients with continuous AF, as seen by these preliminary results. Because of the substrate alterations that electrical remodeling brings about, this procedure as standalone therapy is insufficient for patients with persistent and LSP AF (46
). The altered left atrial substrate beyond the PVs can initiate and sustain AF. Additional linear lesions are necessary in this group. The “Dallas lesion set” was developed to treat this group of patients. It is a set of linear lesions that replicates the left-sided Cox Maze III procedure and can be applied epicardially, on the full beating heart, with a totally thorascopic technique. The surgeon creates lesions at the roof line, the anterior line, and between the roof line and the LAA in this extended linear lesion set (47
). The Dallas lesion set was studied in 30 patients with persistent or LSP AF. The preliminary results are encouraging: 15 of 20 patients (75%) with LSP AF and 9 of 10 patients (90%) with persistent AF had freedom from AF at a follow-up of 6 months (39
). PVI and GP ablation are more efficacious in paroxysmal AF (24
), but the Dallas lesion set can serve as a valuable surgical therapy option in persistent and LSP AF.