Surgery for atrial fibrillation: recent progress and future perspective

Abstract

Development and introduction of radiofrequency ablation devices allowed the maze procedures to be performed safely and easily, further enabling off-pump pulmonary vein isolation through a mini-thoracotomy or thoracoscope. The effects of the maze procedure include prevention of stroke and other complications related to atrial fibrillation, improved cardiac performance, and relief of symptoms. Indications for the maze procedure have been discussed on the basis of the evidence. Pulmonary vein isolation has been shown to be effective in most patients with paroxysmal atrial fibrillation and can be performed with endocardial catheter ablation and minimally invasive epicardial ablation. These two modalities should be compared in terms of the success rate, occurrence of cerebral microembolic signals, capability of additional lesions indicated for persistent or long-standing persistent atrial fibrillation, and closure of the left atrial appendage. Noncontinuous or nontransmural lines of conduction block as a result of incomplete ablation can result in recurrence of atrial fibrillation and induction of atrial tachycardia. Intraoperative verification of conduction block across the ablation lines is recommended to prevent these complications. Volume reduction of the enlarged left atrium or a boxlesion to isolate the entire posterior left atrium may be effective in patients with a dilated left atrium, but the potentially impaired atrial transport function should be considered. Mapping of active ganglionated plexi and their ablation may improve the outcome of the procedure, but the long-term effect on atrial fibrillation and autonomic nerve activities should be examined.

Recent Insights Into the Role of the Autonomic Nervous System in the Creation of Substrate for Atrial Fibrillation

“…Pokushalov et al 74 reported success rates of < 40% at one year after performing isolated GP ablation for symptomatic, drug refractory persistent AF; circumferential isolation of the PVs was needed in these patients to increase the success rate of GP ablation. Recent surgical studies have also attempted to add GP ablation/excision to PV isolation, albeit with varying efficacy 69, 70, 80, 81 . However, it is clear while minimally invasive surgery consisting of bipolar radiofrequency pulmonary vein (PV) isolation and limited GP ablation is effective in reducing atrial fibrillation (AF) in patients with paroxysmal AF, it is less effective in those with persistent AF or long-standing persistent AF 82 .…”

Long-standing persistent effects of atrial volume reduction combined with pulmonary vein isolation

“…Increasing LA size was a significant risk factor for failure of a Maze procedure, and extensive size reduction or expanded lesion sets may be required in patients with a large LA [8]. LA volume reduction procedures have demonstrated an improved conversion rate of AF and increased the LA function postoperatively [4].…”

Autonomic Nervous System Dysfunction

“…Karitsis et al (104) and others (105) demonstrated that when GP ablation was combined with PV isolation, it yielded better results than PV isolation alone, with success rates approaching 80% (104). Recent surgical studies also attempted to add GP ablation and/or excision to PV isolation with varying efficacy (97,98,106,107). The efficacy and durability of this approach has not been established.…”