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  • The incidences of AF and AT have

    2019-06-29

    The incidences of AF and AT have been shown to be relatively high after minimally invasive AF surgery [18–20]. Edgerton et al. [18] demonstrated that Gemcitabine HCl freedom from AF or AT should be assessed by long-term monitoring. Kron et al. [19] showed that 40% of patients could undergo bilateral PV isolation and ablation of GP and the ligament of Marshall through a minimally invasive thoracoscopic procedure. An electrophysiological study investigated patients with atrial arrhythmias and found that the underlying mechanism behind the arrhythmias was the reconnection of the previous PV isolation and isthmus-dependent reentry. Zeng et al. [20] examined patients with recurrent atrial tachyarrhythmias after minimally invasive PV isolation with an electro-anatomical mapping system, and found gaps at the roof and bottom of the PV isolation. They also found gaps in the PV isolation ring and ectopic focus between the left atrial appendage and left superior PV. Closure of the left atrial appendage is an important procedure both in the full-maze and minimally invasive AF procedures, with regard to the prevention of stroke. Staples have been used to close the left atrial appendage in the minimally invasive AF procedure. Recently, a new clip device was introduced and tested in animals and patients [21,22] (Fig. 4). The initial results were favorable, and further trials are required to test the long-term safety and to evaluate the role of the left atrial appendage occlusion in stroke prevention.
    Postoperative AT Although the maze procedure is the gold standard in surgical therapy for AF, the restoration ratio of sinus rhythm from AF is about 90%. Five percent to 10% of patients experience recurrences of AF or AT after the maze procedure [23]. While recurrent AF occurs in some patients with a large left atrium (cardiothoracic ratio >70% and left atrial diameter >80mm) preoperatively, the mechanism of postoperative AT differs from that of recurrent AF. It has become clear that the most common mechanism of postoperative AT is incomplete ablation of the mitral valve annulus and coronary sinus. Wazni et al. [24] reported Replication eye incomplete surgical ablation of the PVs, or the mitral or tricuspid annulus causes postoperative AT after the traditional cut-and-sew maze procedure. Postoperative AT is cured by catheter ablation of the incomplete conduction block. McElderry et al. [25] described a 15% incidence of AT after a modified maze procedure. They found macro-reentries around the surgical incisions caused by residual conduction at the incomplete ablation site in AT patients. The rationale behind the surgical treatment of AF is to create a conduction block. The cut-and-sew technique provides a complete conduction block, and a line of conduction block prevents propagation of abnormal activation and interrupts reentrant circuits. Alternative ablation devices have been developed to replace the cut-and-sew lesions of the original maze procedure in order to simplify the surgical procedure, decrease the risk of bleeding, and shorten the cardiac arrest and operative times during the surgery. However, ablation devices such as traditional cryoablation, RF ablation, microwave, or ultrasound do not necessarily guarantee a transmural and continuous necrosis. However, Lall et al. [2] described that AF surgery with a RF ablation device cured AF in >90% of patients, which is a similar result to that with the traditional cut-and-sew maze procedure. Stulak et al. [26] and Doty et al. [27] reported that the traditional cut-and-sew maze procedure was superior to RF AF surgery for the treatment of AF. Ishii et al. [28] emphasized the importance of complete ablation of the coronary sinus and PVs during AF surgery. They recommend an intraoperative evaluation of the conduction block by pacing from the coronary sinus or PVs in order to prevent postoperative AT (Fig. 5). Krul et al. [29] demonstrated that the periprocedural confirmation of ablation lesions contributed in achieving a high success rate of thoracoscopic video-assisted PV antrum isolation with GP ablation. Henry et al. [30] showed that recurrent AT can be safely and effectively treated by catheter ablation postoperatively, suggesting that the combination of catheter and surgical ablation can improve outcome even in complex patients.