**5. Surgical technique**

There are several procedures that are currently performed to treat AF: the Cox-Maze IV procedure, left atrial lesion sets, pulmonary vein isolation (PVI), and hybrid ablations.

#### **5.1 The Cox-Maze IV procedure**

The Cox-Maze IV replicates the Cut-and-sew Maze lesion set using bipolar RF energy and cryoablation to replace most of the incisions in the Cox-Maze III [2, 48]. Clinical results have shown that the Cox-Maze IV achieves the high success rate of the Cox-Maze III with significant reduction in operative time and lower complication rates [2, 49]. The Cox-Maze IV procedure requires cardiopulmonary bypass. It can be performed either through a median sternotomy or a minimally invasive right thoracotomy approach. The selection of an approach should be based on the presence of concomitant cardiac pathology, patient-specific anatomic characteristics and the experience of the surgeon [2]. Patients who are in AF at the time of surgery and have no intracardiac thrombosis on intraoperative transesophageal echocardiogram are electrically cardioverted and started on intravenous amiodarone. Pacing thresholds are measured from each pulmonary vein [2, 50].

#### **5.2 Median sternotomy approach**

For the standard fashion, the right and left pulmonary veins are bluntly dissected, mobilized and encircled with umbilical tapes. Amiodarone is given and electrical cardioversion is performed if the patient is in AF. Pacing thresholds are performed and pulmonary veins isolation (PVI) is achieved using bipolar clamps. After PVI is completed, exit block is confirmed from each pulmonary vein [2, 50].

To perform the right atrial lesion set, the patient is then cooled to 34°C. Lesions from right atrial lesion set are performed on the beating heart. Two purse-string sutures are created at the base of both right and left atrial appendage which is large enough to place a jaw of bipolar RF clamp. Right atrial free wall ablation is first performed through the previously made purse-string suture down toward the aortic side of the right atrial appendage. Right atriotomy is created vertically toward the atrioventricular (AV) groove. Superior and Inferior vena cava lesions are performed using RF clamp applying from inferior aspect of previous right atriotomy incision. Next, endocardial ablation is created using a linear cryoprobe starting from the right atriotomy down onto the 2 o'clock position of the tricuspid annulus. Then another endocardial ablation lesion is performed using the linear cryoprobe inserted through the previous made purse-string suture down to the 10 o'clock position of tricuspid annulus (this lesion can be omitted in case of small right atrium and no tricuspid regurgitation) [2, 50].

After the aortic clamp is on and the heart is completely arrested, the left atrial lesions set is performed. The left atrial appendage is identified and amputated, and an ablation is performed through the amputated left atrial appendage. The bipolar RF clamp is used to create a connecting lesion into the left inferior or superior pulmonary vein. The left atrial appendage is then oversewn in a double layer. Methylene blue is then used to mark the coronary sinus. Then left atriotomy incision is made, the roof and floor lesions are created with bipolar RF clamp. From the inferior margin of left atriotomy, bipolar RF clamp is applied to create ablation line toward the mitral annulus and across the coronary sinus. A bell-shaped cryoprobe is used to make and endocardial lesion to the mitral annulus at the end of the mitral isthmus lesion. An epicardial cryoablation is performed over the coronary sinus in line with the endocardial lesion to complete the left atrial isthmus lesion [2]. Some institutes use only cryoablation to create the Cox-Maze IV lesion set. The atriotomy is then closed. The patient is weaned from cardiopulmonary bypass and the sternotomy closed in a standard fashion.

#### **5.3 Right minithoracotomy approach**

The patient is intubated with a double-lumen endotracheal tube with right lung deflation. Femoral cannulation is obtained for cardiopulmonary bypass. A small

*Concomitant Atrial Fibrillation Surgery DOI: http://dx.doi.org/10.5772/intechopen.106066*

minithoracotomy is performed over the fourth intercostal space, midaxillary line. For the right minithoracotomy approach, the ablation lesions set remains the same. The right atrial lesion ablation is performed through 3 purse-string sutures as in a minimally invasive approach. In case of left atrial lesion set, the pattern of ablation also remains the same except for the left pulmonary vein isolation is performed endocardially using cryoablation probe to connect the superior and inferior box lesions. The left atrial appendage exclusion is performed by double layer oversewing endocardially.

#### **5.4 Cox-Maze IV surgical result**

The Cox-Maze III procedure had excellent success rates for the treatment of AF. One of the studies at Washington University examined the outcomes of 198 patients who underwent the Cox-Maze III procedure. Their study showed a 97% freedom from symptomatic AF with a mean follow up of 5.4 years and no difference in recurrence when comparing patients who received a stand-alone Cox-Maze III versus patients who received a concomitant procedure [32]. Similar results have been obtained from other studies with the cut-and-sew method [12, 14, 51]. However, very few of these patients had prolonged monitoring or even follow-up electrocardiograms or prolonged monitoring to assess the rhythm.

The modification of the Cox-Maze IV simplified the traditional procedure and made it easier to perform. This allowed for the development of minimally invasive approaches and more widespread adoption, allowing for many more patients to receive surgical ablation at the time of concomitant surgery [52]. In 2018, the number of patients had increased to more than 30,000 by estimates using the Society of Thoracic Surgeons (STS) Adult cardiac surgery database [47, 52]. Badhwar et al reported an overall increase of 50% in performing concomitant surgical ablation from the year of 2011–2014 [47, 52].

The recent study from Damiano group demonstrated an excellent long-term efficacy at maintaining sinus rhythm of the Cox-Maze IV with 77% overall freedom from recurrent ATAs at 10 years follow-up [52]. Moreover, at late follow-up, the results of the Cox-Maze IV remained superior to those reported for catheter ablation and other forms of surgical ablation for AF [52].

The findings from other studies also support the recommendation that the Cox-Maze IV should be considered in all patients undergoing concomitant cardiac surgery if it can be performed without adding morbidity or mortality to the procedure [52–56].

#### **5.5 Left atrial procedures**

Most centers have advocated performing ablation confined to the atrium only to treat AF. Since the majority of paroxysmal AF appears to originate from the pulmonary veins and the posterior of left atrium. Left atrial lesion set typically involves pulmonary vein isolation, with a lesion to the mitral annulus and the left atrial appendage removal/exclusion. The advantage of avoiding right atrial lesions is a potential of lower rate of postoperative pacemaker implantation [57]. However, Gillinov et al. published a large series demonstrating the omission of the left atrial isthmus lesion resulted in a significantly higher incidence of recurrent AF in persistent AF patients [58]. To complete this isthmus lesion, it is important to ablate the coronary sinus in line with the endocardial lesion. Some studies have shown that isolation of the entire posterior left atrium is associated with improved outcomes compared with isolation of the pulmonary veins alone and had significantly higher

rate freedom from AF when compared with left atrial set alone [59, 60]. Some studies have shown that AF can originate from the right atrium in up to 30% [61–63].

#### **5.6 Pulmonary vein isolation (PVI)**

Pulmonary vein isolation can be performed without cardiopulmonary bypass with minimally invasive technique via either minithoracotomy or thoracoscopy and can be easily added to other cardiac surgical procedure. Haissaguerre study documented that the triggers for paroxysmal AF originate from pulmonary veins in the majority of cases [64]. However, up to 30% of triggers may originate outside the pulmonary veins [65]. This is further informed by anatomic substrates that could be the generation of AF as extrapulmonary triggers located at the superior vena cava, the ligament of Marshall, and the epicardial ridge between the left pulmonary vein and the left atrial appendage [66]. The pulmonary veins can be isolated separately or as a box lesion. The most common approach for treatment of lone AF uses an endoscopic, portbased approach. Bipolar RF clamps are favored but unipolar RF, cryoablation, and high-intensity focused ultrasound devices have also been used [43, 67, 68]. Although energy sources such as microwave proved not to deliver effective lesions [69]. The application of RF bipolar clamp to create PVI antral pairs via bilateral thoracotomies has been established as a safe procedure with reasonable short-term efficacy [70]. There is a study that demonstrated the late gaps in ablation lines occurred after epicardial PVI ablation regardless of previously exit block confirming intraoperatively [17]. This could be a supporting idea of beneficial combining epicardial PVI with endocardial ablation [31]. The FAST trial, a multicenter randomized trial, compared 63 patients who received linear antral pulmonary vein isolation by catheter ablation and 61 patients who received bipolar RF PVI and ganglion plexus ablation. Most patients had paroxysmal AF. At 1 year, freedom from left atrial arrhythmia without ATA was 66% for surgical ablation versus 36% for catheter ablation [71].

This procedure will be completed until the left atrial appendage has been addressed. In the past, this had been done by stapling across the base of the left atrial appendage. This requires careful surgical technique and attention due to it can result in tears and bleeding [72]. Clip devices have been developed to address this difficulty. They improved efficacy and safety when compared to staplers [73, 74].

#### **5.7 Hybrid ablations**

To lessen the invasiveness of surgical ablation, extended epicardial ablation was introduced, which can be placed through thoracoscopic ports. However, these probes have not been able to achieve the same degree of transmurality created by bipolar clamps [30]. This led to the idea of combining endocardial ablation via transcatheter techniques and epicardial ablation via surgical techniques in a hybrid approach. Based on current experience, the hybrid approach with the most effective outcomes and safety profile appears to be bilateral pulmonary vein procedures performed surgically with left atrial appendage management combined with different endocardial ablation protocol [31]. The principles of these approaches are based on the understanding that it is possible to apply mapping techniques from electrophysiologists to surgical epicardial ablation techniques when performed on beating heart [31].

Currently, there are several procedures being performed surgically, combining with endocardial ablation e.g., PVI procedures either bilateral thoracoscopic/ minithoracotomy approach or unilateral thoracoscopic PVI posterior encircling box *Concomitant Atrial Fibrillation Surgery DOI: http://dx.doi.org/10.5772/intechopen.106066*

lesion with or without left atrial appendage management. There is also an alternative approach to posterior left atrial wall epicardial ablation lesion (pericardioscopic epicardial debulking ablation procedures, also known as "convergent method") [31].

The recent expert guideline favors the hybrid approach over percutaneous catheter ablation in terms of results in a subgroup of symptomatic AF patients who have had failed medical and percutaneous catheter ablation treatment [31].
