Unilateral Left-sided Thoracoscopic Ablation of Atrial Fibrillation

Thoracoscopic surgical ablation has evolved into a valid and effective treatment option, especially in patients with more persistent forms of atrial fibrillation. A significant part of this development is due to the capability of biparietal bipolar radiofrequency clamps to create long-lasting transmural lesions. To date, all commercially available bipolar clamps require a bilateral thoracoscopic approach. Here, we describe the surgical technique of a unilateral left-sided thoracoscopic approach for surgical atrial fibrillation ablation on the beating heart. Thoracoscopic surgical ablation has evolved into a valid and effective treatment option, especially in patients with more persistent forms of atrial fibrillation. A significant part of this development is due to the capability of biparietal bipolar radiofrequency clamps to create long-lasting transmural lesions. To date, all commercially available bipolar clamps require a bilateral thoracoscopic approach. Here, we describe the surgical technique of a unilateral left-sided thoracoscopic approach for surgical atrial fibrillation ablation on the beating heart. Dr Maesen discloses a financial relationship with Medtronic and AtriCure; Dr La Meir with AtriCure.The Videos can be viewed in the online version of this article [https://doi.org/10.1016/j.athoracsur.2020.01.057] on http://www.annalsthoracicsurgery.org. Dr Maesen discloses a financial relationship with Medtronic and AtriCure; Dr La Meir with AtriCure. The Videos can be viewed in the online version of this article [https://doi.org/10.1016/j.athoracsur.2020.01.057] on http://www.annalsthoracicsurgery.org. Despite numerous studies, the exact pathophysiologic mechanisms underlying the perpetuation of persistent atrial fibrillation (AF) are still not understood.1Schotten U. Verheule S. Kirchhof P. Goette A. Pathophysiological mechanisms of atrial fibrillation: a translational appraisal.Physiol Rev. 2011; 91: 265-325Crossref PubMed Scopus (882) Google Scholar As a consequence, current invasive AF treatment is still in large part influenced by two major breakthroughs: first, the development of the Cox-Maze procedure,2Cox J.L. The surgical treatment of atrial fibrillation. IV. Surgical technique.J Thorac Cardiovasc Surg. 1991; 101: 584-592Abstract Full Text PDF PubMed Google Scholar and second, the seminal observation by Haissaguerre and colleagues3Haissaguerre M. Jais P. Shah D.C. et al.Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins.N Engl J Med. 1998; 339: 659-666Crossref PubMed Scopus (6332) Google Scholar that focal electrical discharges of the pulmonary veins can initiate AF. For the reason that the complexity of AF conduction patterns1Schotten U. Verheule S. Kirchhof P. Goette A. Pathophysiological mechanisms of atrial fibrillation: a translational appraisal.Physiol Rev. 2011; 91: 265-325Crossref PubMed Scopus (882) Google Scholar,4de Groot N.M. Houben R.P. Smeets J.L. et al.Electropathological substrate of longstanding persistent atrial fibrillation in patients with structural heart disease: epicardial breakthrough.Circulation. 2010; 122: 1674-1682Crossref PubMed Scopus (260) Google Scholar prevents the development of a true mechanism-based, patient-tailored AF treatment, we decided to combine the best of both treatments into one approach, combining thoracoscopic epicardial AF ablation with transvenous endocardial catheter ablation.5Pison L. La Meir M. van Opstal J. Blaauw Y. Maessen J. Crijns H.J. Hybrid thoracoscopic surgical and transvenous catheter ablation of atrial fibrillation.J Am Coll Cardiol. 2012; 60: 54-61Crossref PubMed Scopus (185) Google Scholar After 3 years, this single-step hybrid procedure results in freedom from atrial tachyarrhythmias off antiarrhythmic drugs in 80% of paroxysmal AF and 79% of nonparoxysmal AF patients.6Maesen B. Pison L. Vroomen M. et al.Three-year follow-up of hybrid ablation for atrial fibrillation.Eur J Cardiothorac Surg. 2018; 53: i26-i32Crossref PubMed Scopus (42) Google Scholar More recently, we optimized our surgical approach from a bilateral to a unilateral left-sided thoracoscopic procedure, thereby avoiding right-sided complications and potentially reducing postoperative pain. Here, we describe the surgical technique. The left-sided video-assisted thoracoscopic AF ablation is performed on the beating heart under general anesthesia with double-lumen endotracheal tube placement for selective right lung ventilation. The patient is positioned in the dorsal decubitus position with both arms next to the body in supported hanging position dorsal to the thorax. An inflatable bag is used to lift the left hemithorax (Figure 1). Before incision, absence of left atrial appendage thrombi is confirmed on transesophageal echocardiography. The transesophageal echocardiography probe is then retracted to 6 inches (15 cm) from the teeth to prevent potential thermal injury to the esophagus by heat transfer during ablation After left lung deflation, a 5-mm camera port is introduced into the fifth intercostal space at the midaxillary line and two 5-mm workings ports in the third and the seventh intercostal space at the anterior axillary line of the left hemithorax (Figure 1). The pericardium is opened posterior to the phrenic nerve using monopolar cautery and thoracoscopic scissors (Figure 2A, Video 1). Through the oblique sinus, the pericardial reflection between the inferior caval vein and the right inferior pulmonary vein (RIPV) is opened by blunt dissection to get access to the intrapericardial space on the right side (Figure 2B, Video 2). Hereafter, also the pericardial reflection medial from the posterior aspect of the right superior pulmonary vein (RSPV) toward the pulmonary artery is dissected through the oblique sinus. Through the transverse sinus, opening of the pericardial reflection between the superior caval vein and RSPV is similarly obtained (Figure 2C, Video 3). Through the oblique sinus, a light dissector (Lumitip; AtriCure, Mason, OH) is then placed in the predissected plane medial from the RSPV to encircle the left pulmonary veins, medial to the ligament of Marshall, with a rubber glidepath and a biparietal bipolar radiofrequency clamp (Synergy System; AtriCure [Video 4]). Antral ablation of the left pulmonary veins is continued until the tissue conduction graph drops within 5 seconds, but respecting a minimum of 6 applications (Figure 2D, Video 4). Next, the oblique sinus is entered with a unidirectional bipolar radiofrequency rail device (Coolrail; AtriCure) to create an ablation line that connects both inferior pulmonary veins (inferior line; Figure 3A, Video 5). To prevent thermal damage to the esophagus directly located below the posterior pericardium, the pericardial space is rinsed with saline at room temperature each time before moving the rail device to the next ablation position. Through the transverse sinus, an ablation line connecting both superior pulmonary veins is applied in the same manner (roof line; Video 5). The ablation at each location on inferior and roof line is continued until the power graph drops within 20 seconds. Before the ablation of the right pulmonary veins, preoxygenation is started by augmenting the ventilator’s oxygen supply to 100%. Next, from the oblique sinus the light dissector is positioned behind the RIPV and retrieved above the RSPV to encircle the right pulmonary veins laterally with the rubber glidepath (Figure 3B, Video 6). The clamp is then carefully placed between the right and left veins in the oblique sinus. That allows manipulation of the pericardium around the base of the clamp, until the clamp is completely within the pericardial sac. The tip of the closed clamp is then positioned lateral to the RIPV, and the clamp is carefully opened and positioned around the right veins (Figure 3C, Video 7). The jaw of the clamp behind the RIPV is safely guided by the rubber glidepath, but attention is paid to the atrial wall as it should be lifted when the jaw medial to the RIPV is advanced. The initial closure of the clamp will not comprise both veins, but with each ablation, the clamp can be advanced until both veins can be safely ablated. Because the left lung is deflated, clamping of the right veins will provoke a transient decrease in blood pressure and oxygen saturation. Therefore, time for recuperation of systolic blood pressure greater than 100 mm Hg and of oxygen saturation greater than 95% is respected between consequential ablations. During the ablation of the right pulmonary veins, the position of the distal jaw in relation to the RSPV can be evaluated through the transverse sinus (Figure 3D). If needed, the clamp can be further advanced or repositioned to ensure ablation of both veins. The retrieving of the clamp should be done under vision, using a caudal-lateral movement until the tip of the clamp is no longer behind the RIPV, followed by gentle removal out of the pericardial sac. Completeness of the ablation lesions can be confirmed with epicardial testing of exit and entrance block (Video 8), but in most cases we perform endocardial electrophysiologic validation as part of a hybrid AF ablation procedure. Finally, closure of the left atrial appendage is performed using an epicardial clipping device (AtriClip Pro 2; AtriCure [Video 9]. The left-sided procedure has been routinely performed since 2014. Indeed, since 2017, more than 90% of all our patients have been treated with this approach. In any case, every procedure is started from the left side because the dissection of the pericardial folds is more straightforward and can be performed toward the pericardium instead of toward the heart. The reason to convert to a bilateral approach can be anatomic (ablation devices are too short, no safe pulmonary vein encircling possible) or electrophysiologic (‘persistent’ paroxysmal AF when the superior caval vein is also ablated). After the learning curve, the average thoracoscopic operation time is 90 to 120 minutes. The transvenous endocardial validation and additional ablation has more variation, but on average is also 90 to 120 minutes. Therefore, the total procedure can be performed in 3 to 4 hours, which is comparable to a full Cox maze IV procedure, but without the need for cardiopulmonary bypass. The complications associated with this procedure are comparable to those of a bilateral approach. In more than 200 cases, there was one conversion to sternotomy because of a lesion in the superior caval vein. We have described the surgical technique of unilateral left-sided thoracoscopic AF ablation to create a so-called box lesion and left atrial appendage closure. This procedure requires advanced thoracoscopic skills, but is safe and feasible, and can be taught. Because right thoracoscopy is avoided, reduction of complications and postoperative pain is to be expected. The authors acknowledge the operative teams at both centers for their continued support. eyJraWQiOiI4ZjUxYWNhY2IzYjhiNjNlNzFlYmIzYWFmYTU5NmZmYyIsImFsZyI6IlJTMjU2In0.eyJzdWIiOiI1N2E0MjcwYmI0MGNkZWQyNjBjMzU3NmUxZjQzOGZhNCIsImtpZCI6IjhmNTFhY2FjYjNiOGI2M2U3MWViYjNhYWZhNTk2ZmZjIiwiZXhwIjoxNjc4NTU3MjUxfQ.kLBojyFfOrGm2uRzO0d5tVQjBaN4MWA775LBj2VNCBAftEx7s3XJ93VC7DJXOm_y2gxmQ677ai7E7vQR6v7oaxi5MmWqGlYteGQH6CUmWLyBIOGiuutOhSxysFfyaWra1ngKX8GiaLbNbmUQzZdRT7-yNcGa4RHKuXE42Rd-1ID_4KC53ooh-vZkRA99Az2FA-4do39R5YabODD7yIfZU96lRgwAfcSlczh8gg-TKlVoxlG22mRKXBq2HK1bJwkve8Rm8K7jeHyf0I-Pn3noTsI6Zw3QKSP5Nt7gU0Npx3sM1LBxvQvDpklLf8lzIvAJSza68MRH-ncJPhcBIoQ9sg Download .mp4 (12.94 MB) Help with .mp4 files Video 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