doi:10.1510/mmcts.2009.004390
Complete biatrial ablation of atrial fibrillation with bipolar radiofrequency Stefano Benussi*, Maurizio Taramasso, Alberto Pozzoli, Ylenia A. Privitera, Micaela Cioni, Andrea Giacomini, Ottavio Alfieri Department of Cardiothoracic, San Raffaele Scientific Institute, Via Olgettina 60, 20132 Milan, Italy Here we report the description of a simple, safe and reproducible technique to perform a complete biatrial set of lines, entailing left and right isthmus lines, using bipolar radiofrequency as a solo modality or in combination with cryoenergy.
Keywords: Atrial fibrillation; Biatrial ablation; Cryoenergy; Radiofrequency
Introduction Atrial fibrillation (AF) affects 1% of the general population and its prevalence in patients referred for mitral valve surgery is up to 70%–80% w1–3x. The therapeutic goal in the treatment of AF is to restore mechanical function of the atrium with a physiological atrio-ventricular synchronicity, to reduce the thromboembolic risk and possibly to avoid anticoagulant and antiarrhythmic drugs. The Cox-maze III operation is the gold standard in the treatment of patients with permanent AF w4x. Several modifications of the maze procedure have been created, and the ablation lines are now performed with different sources of energy w4–6x. Bipolar radiofrequency (RF) is to date the most effective way to perform transmural atrial scars for the surgical ablation of AF during open-heart surgery. A complete left and right lesion set has a proven role in improving AF cure rate w5, 7, 8x. Nevertheless, bipolar devices are generally not used to perform the mitral and tricuspid lines. This is because of their clamping feature and their efficacy that could potentially increase the risk of coronary injury. Many surgeons generally prefer either * Corresponding author: Tel.: q39 02-26437102; fax: q39 0226437125. E-mail: [email protected] 2010 European Association for Cardio-thoracic Surgery
to avoid the mitral ablation or to complete such an ablation using adjunctive unipolar devices, thus making the procedure less effective, more expensive and longer. In this context, the most convenient unipolar energy source to combine with bipolar RF is probably cryoablation w9x, which is safe, transmural and now feasible in most countries using resterilizable devices. We have recently reported the safety and the feasibility of the left isthmus line and of tricuspid connecting ablations with a bipolar RF device w10–12x. Here we report the results of a simple, safe and reproducible technique to perform a complete biatrial set of lines, entailing left and right isthmus lines, using bipolar RF or in combination with cryoenergy.
Patients and methods The study population consists of 80 consecutive patients who underwent surgical AF treatment with complete biatrial ablation using bipolar RF as a solo modality between February 2007 and July 2009. In 91% of the cases (73/80 patients), the ablation of the AF was a concomitant procedure (83% of the patients had primary mitral valve disease as the main indication to open-heart surgery), while in seven cases the primary indication to surgery was isolated AF. 1
S. Benussi et al. / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2009.004390 The right ablation lines consisted of a right isthmus ablation alone in 26 patients, of a right isthmus plus anteromedial tricuspid ablation in 20 patients and of a complete maze III set of lines in 34 patients. The type of AF was paroxysmal in three patients (4%), persistent in 17 patients (21%) and permanent in 60 patients (75%).
Surgical technique Transesophageal echocardiography is performed in all patients within 24 h before the surgery to exclude intracavitary thrombosis. When available, coronary angiography is thoroughly considered to discern the specific coronary anatomy. All ablations were carried out using bipolar RF devices: 43% with Cobra Bipolar (Estech Inc, Camino Ramon, CA, USA), 44% with Isolator (Atricure Inc, Cincinnati, OH, USA) and 13% with the BP2 (Medtronic Inc, Minneapolis, MN, USA). Cryoablations on the mitral and/or tricuspid annulus were added in 21 patients. Left atrial ablation (Videos 1–3)
Video 3. Left atrial connecting ablation and left appendage obliteration. After the cardioplegic arrest, the left atrium is opened parallel to the Waterstone groove, the projection of the needle on the posterior mitral annulus is identified and the needle is removed. The mitral ablation line is performed with the proximal part of the clamp intersecting the atriotomy and the tip of the inner jaw biting the posterior mitral annulus. The coronary sinus that passes along the atrial side of the AV groove is thus circumferentially ablated. Such ablation is generally repeated at least once. Two endoepicardial lines are carried out to connect the two encirclings, one on the roof of the left atrium connecting the right superior PV to the left superior PV and one from the inferior part of the atriotomy to the left inferior PV. The last ablation line is performed by clamping the device with one jaw in a left pulmonary vein and the other in the left appendage. After completing the left ablation, the left appendage is meticulously oversewn at its base with a watertight double layer of 4-0 polypropylene (mattress followed by over and over suture).
Before left appendage closure, it is preferable to purge it from air, which may possibly embolize in the case of a residual endoleak. A slight modification of the described left atrial ablation procedure makes the same lesion set feasible with a transseptal incision, when this approach is preferred w15x.
Video 1. Isolation and encircling of pulmonary veins. The encircling ablations of the pulmonary vein (PV) orifices are performed epicardially, usually on-pump. The device is clamped on the antral portion of the atrium, around the PV couple to be isolated. Two or more parallel ablations are normally performed based on tissue thickness and visual fat content and also depending on the platform being used w12–14x.
Video 2. The anatomy of the coronary arteries is then inspected after lifting the fully decompressed beating heart. The coronary-free segment of the atrioventricular (AV) groove between the terminal branch of the right coronary artery and of the circumflex artery is identified. A 20-mm hypodermic needle is placed on the atrial side of the coronary sinus, in order to identify the middle point of such a target area.
2
Right atrial ablation (Videos 4–7)
Video 4. Right atrial ablation. When a complete maze III type lesion set is planned, the right atriotomy is performed perpendicular to the antero-posterior AV groove around the inferior vena cava (IVC) cannulation site. The groove is entered by separating the sulcus fat from the atrial wall and is developed with the scissors by blunt dissection down to the plane of the tricuspid annulus, corresponding to the anterior portion of the posterior leaflet. The right coronary artery is clearly identified by blunt inspection with the scissors and is safely left on the ventricular side of the dissection. Optionally, it may be looped. This part of the procedure may be performed just after cross-clamping, during cardioplegia administration.
S. Benussi et al. / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2009.004390
Video 5. Then the bipolar device is inserted: the tip of the epicardial jaw is sled in the dissected portion of the AV groove, checked for biting the tricuspid, and the ablation is performed. The edge of the atriotomy is tractioned upward while the clamp is forced down in the groove to prevent backsliding of the device during energy deployment. Liberal clamping of the tricuspid leaflets must be avoided to prevent valve impairment.
Video 6. After incision or minimal amputation of the tip of the right appendage, the same type of dissection is carried out on the medial aspect of the right atrium. The blunt dissection is carried out with the scissors following the atrial wall down to the level of the anterior tricuspid annulus. The bipolar device is positioned with the external jaw following the dissected pathway down until the internal jaw intersected the tricuspid annulus at the level of the medial portion of the anterior leaflet. An additional endo-epicardial ablation is performed from the appendage incision towards the main atriotomy.
Video 8. Usually two (possibly simultaneous) cryoablations are deployed endocardially on the mitral annulus and on the corresponding epicardial aspect, to fully ablate the coronary sinus. This last ablation should be cautiously pondered in presence of a left dominant coronary artery.
Cryoablation is used to complete the lesion set when clamping the mitral annulus is deemed unfeasible (adhesion, thick AV tissue, annular calcifications) or unsafe (left dominant coronary system or it is impossible to visually assess coronary distribution, such as via a thoracotomy approach) or for any other reasons based on the surgeon’s preference (Video 8). Cryoablation on the tricuspid annulus is generally not necessary, but when preferred to bipolar RF it is preceded by the same AV groove dissection with right coronary artery dislocation to protect the vessel from possible cryothermal injury w16x. After weaning from the pump, possible endoleaks across the left appendage suture line are ruled out with transesophageal echocardiography. Postoperative management and follow-up Perioperative antiarrhythmic prophylaxis with cordarone was administered for three to six months in the absence of contraindications. Follow-up was complete in 100% of the cases.
Video 7. The right atriotomy is then connected with the inferior vena cava during a short period of snare releasing and with the superior vena cava (SVC) in an endo-epicardial fashion. While the SVC should be ablated at its dorsal aspect to decrease the risk of sinus node dysfunction, the IVC is better addressed by clamping ventrally to prevent possible phrenic nerve biting.
When a simpler right atrial set of lines is opted for (in the case of a small right atrium, recent onset or paroxysmal AF, or unwillingness to possibly increase postoperative pacemaker implantation) and only a cavo-tricuspid ablation is planned, a standard right atriotomy parallel to the AV groove is generally preferred.
Clinical evaluation, standard 12 leads ECG, Holter and transthoracic echocardiography monitoring were performed three, six and 12 months after the operation in our outpatient clinic dedicated to the surgical treatment of arrhythmias. Statistical analysis Statistical analysis has been conducted using the JMP 7.0 software (SAS Institute Inc, NC, USA). Continuous variables are presented as mean"SD and categorical variables are expressed as percentages. Univariable comparisons have been performed either with the paired t-test or ANOVA for parametric or the Wilcoxon test for non-parametric continuous data and likelihood ratio for categorical data. 3
S. Benussi et al. / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2009.004390
Results Preoperative demographic and echocardiographic data are detailed in Table 1 and the open-heart procedures of the study group are showed in Table 2. Procedural success was 100% and no complications were recorded intraoperatively. In-hospital (30-day) mortality was 0%. No cases of myocardial ischaemia were observed and one major bleeding requiring surgical revision occurred. The incidence of stroke was 0% and 5% of the patients (4/80 patients) required permanent pacemaker implantation, with no differences depending on the type of right ablation lines. The median length of hospital stay was 7; 6 to 12 days, without any difference between RF ablation alone and cryoablation plus RF. Follow-up was 100% complete. At six months, the incidence of sinus rhythm (SR) was 84% in patients Table 1. Preoperative data Patients (n) Male/female Age at surgery (years) NYHA functional class • NYHA I (patients) • NYHA II (patients) • NYHA III (patients) • NYHA IV (patients) Ejection fraction (%)* LVEDD (mm) Left atrial volume (ml) Type of AF • Paroxysmal (patients) • Persistent (patients) • Permanent (patients) Duration of AF (months)*
80 40/40 64"11 18 (22%) 43 (54%) 15 (19%) 4 (5%) 60; 50–60 54"9 140"54 3 (4%) 17 (21%) 60 (75%) 35; 8–89
Values are expressed as number and (percentage). *Data are not normally distributed, so variables are expressed as: median; first quartile–third quartile. NYHA, New York Heart Association; LVEDD, left ventricle enddiastolic diameter; AF, atrial fibrillation. Table 2. Associated pathology Mitral repair Mitral replacement • Biological • Mechanical Tricuspid annuloplasty Tricuspid replacement CABG Aortic valve replacement • Biological • Mechanical Other procedures Values are expressed as number and (percentage). CABG, coronary aortic bypass grafting.
4
35 (44%) 32 (40%) 9 (28%) 23 (72%) 46 (58%) 2 (3%) 9 (11%) 10 (13%) 4 (40%) 6 (60%) 7 (9%)
ablated with RF alone and 81% in patients treated with cryoablation plus RF (Ps0.9). No cases of atrial flutter were reported during followup. Freedom from antiarrhythmic drugs (class I and III) was 60% at last follow-up. Two patients died during follow-up, one from stroke and one from acute myocardial infarction. No major bleedings due to oral anticoagulation were reported at follow-up.
Discussion Bipolar RF has become the most popular device in the field of open-heart ablation, because of its safety (only the clamped tissue can be significantly heated and collateral damage is unlikely) and its efficacy in yielding complete tissue penetration of the lesions w17, 18x. However, coronary injury has been described after ablation with all sorts of energy sources, prompting reluctance towards performing the connecting line to the mitral and the tricuspid annuli with a bipolar clamp w19, 20x. When dealing with persistent AF, concomitant left atrial ablation must entail connecting lines between the encirclings and most importantly to the mitral annulus, since simple PV isolation has been related to poorer SR recovery rate and a higher incidence of left flutter w9, 10, 17x. Similarly, a recent meta-analysis indicated the addition of right atrial ablations to significantly improve rhythm outcome of concomitant ablation surgery w21x. We recently reported two simple and safe techniques to perform all left and right atrial ablations with a single bipolar device, pointing out the importance of tailoring accurately the route of the mitral and tricuspid lines on the individual coronary anatomy w10, 11x. The same approach can easily be performed through a transseptal access to the left atrium w15x. Our clinical experience shows that a complete biatrial ablation with bipolar device is feasible and safe: we did not record any complication related to AV groove ablation or postoperative myocardial ischaemia and only one major bleeding event occurred. The results of our series were actually satisfactory with a freedom from AF at six months after surgery )80%. A complete biatrial Cox-maze III set lesion can be safely performed with bipolar radiofrequency as a solo modality, with satisfactory perioperative and longterm results in terms of restoration of SR. This is particularly cost-effective when and where resterilizable unipolar devices are not available. When clamping on
S. Benussi et al. / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2009.004390 the mitral annulus or on the tricuspid annulus is deemed unsafe, unfeasible or otherwise undesired, cryoablation may be used to complete the isthmus lines with comparable safety and excellent results.
References w1x Falk RH. Atrial fibrillation. N Engl J Med 2001; 344:1067–1078. w2x Obadia JF, El Farra M, Bastien OH, Lie`vre M, Martelloni Y, Chassignolle JF. Outcome of atrial fibrillation after mitral valve repair. J Thorac Cardiovasc Surg 1997;114:179–185. w3x Brodell GK, Cosgrove D, Schiavone W, Underwood DA, Loop FD. Cardiac rhythm and conduction disturbances in patients undergoing mitral valve surgery. Cleve Clin J Med 1991;58: 397–399. w4x Cox JL. Atrial fibrillation II: rationale for surgical treatment. J Thorac Cardiovasc Surg 2003;126: 1693–1699. w5x Benussi S, Nascimbene S, Calori G, Denti P, Ziskind Z, Kassem S, La Canna G, Pappone C, Alfieri O. Surgical ablation of atrial fibrillation with a novel bipolar radiofrequency device. J Thorac Cardiovasc Surg 2005;130:491–497. w6x Melby SJ, Zierer A, Bailey MS, Cox JL, Lawton JS, Munfakh N, Crabtree TD, Moazami N, Huddleston CB, Moon MR, Damiano RJ Jr. A new era in the surgical treatment of atrial fibrillation: the impact of ablation technology and lesion set on procedural efficacy. Ann Surg 2006;244:583– 592. w7x Prasad SM, Maniar HS, Diodato MD, Schuessler RB, Damiano RJ Jr. Physiological consequences of bipolar radiofrequency energy on the atria and pulmonary veins: a chronic animal study. Ann Thorac Surg 2003;76:836–842. w8x Gillinov AM, McCarthy PM. Atricure bipolar radiofrequency clamp for intraoperative ablation of atrial fibrillation. Ann Thorac Surg 2002;74: 2165–2168. w9x Gaita F, Riccardi R, Caponi D, Shah D, Garberoglio L, Vivalda L, Dulio A, Chiecchio A, Manasse E, Gallotti R. Linear cryoablation of the left atrium versus pulmonary vein cryoisolation in patients with permanent atrial fibrillation and valvular heart disease: correlation of electroanatomic mapping and long-term clinical results. Circulation 2005;111:136–142.
w10x Benussi S, Nascimbene S, Galanti A, Fumero A, Dorigo E, Zerbi V, Cioni M, Alfieri O. Complete left atrial ablation with bipolar radiofrequency. Eur J Cardiothorac Surg 2008;33:590–595. w11x Benussi S, Galanti A, Nascimbene S, Fumero A, Dorigo E, Zerbi V, Alfieri O. Complete right atrial ablation with bipolar radiofrequency. Ann Thorac Surg 2009;87:1573–1576. w12x Benussi S, Galanti A, Zerbi V, Privitera YA, Iafelice I, Alfieri O. Electrophysiologic efficacy of irrigated bipolar radiofrequency in the clinical setting. J Thorac Cardiovasc Surg 2010;139:1131–1136. w13x Bugge E, Nicholson IA, Thomas SP. Comparison of bipolar and unipolar radiofrequency ablation in an in vivo experimental model. Eur J Cardiothorac Surg 2005;28:76–80. w14x Damiano RJ Jr, Voeller RK. Biatrial lesion sets. J Interv Card Electrophysiol 2007;20:95–99. w15x Gillinov AM, Svensson LG. Ablation of atrial fibrillation with minimally invasive mitral surgery. Ann Thorac Surg 2007;84:1041–1042. w16x Benussi S, Nascimbene S, Calvi S, Alfieri O. A tailored approach to prevent complications during left atrial ablation. Ann Thorac Surg 2003;75: 1979–1981. w17x Gillinov AM, Bhavani S, Blackstone EH, Rajeswaran J, Svensson LG, Navia JL, Pettersson BG, Sabik III JF, Smedira NG, Mihaljevic T, McCarthy PM, Shewchik J, Natale A. Surgery for permanent atrial fibrillation: impact of patient factors and lesion set. Ann Thorac Surg 2006;82: 502–514. w18x Gammie JS, Haddad M, Milford-Beland S, Welke KF, Ferguson TB Jr, O’Brien SM, Griffith BP, Peterson ED. Atrial fibrillation correction surgery: lessons from the Society of Thoracic Surgeons National Cardiac Database. Ann Thorac Surg 2008;85:909–914. w19x Sueda T, Shikata H, Mitsui N, Nagata H, Matsuura Y. Myocardial infarction after a maze procedure for idiopathic atrial fibrillation. J Thorac Cardiovasc Surg 1996;112:549–550. w20x Berreklouw E, Bracke F, Meijer A, Peels KH, Relik D. Cardiogenic shock due to coronary narrowings one day after a MAZE III procedure. Ann Thorac Surg 1999;68:1065–1066. w21x Barnett SD, Ad N. Surgical ablation as treatment for the elimination of atrial fibrillation: a metaanalysis. J Thorac Cardiovasc Surg 2006;131: 1029–1035.
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Complete biatrial ablation of atrial fibrillation with bipolar radiofrequency Stefano Benussi*, Maurizio Taramasso, Alberto Pozzoli, Ylenia A. Privitera, Micaela Cioni, Andrea Giacomini, Ottavio Alfieri Department of Cardiothoracic, San Raffaele Scientific Institute, Via Olgettina 60, 20132 Milan, Italy Here we report the description of a simple, safe and reproducible technique to perform a complete biatrial set of lines, entailing left and right isthmus lines, using bipolar radiofrequency as a solo modality or in combination with cryoenergy.
Keywords: Atrial fibrillation; Biatrial ablation; Cryoenergy; Radiofrequency
Introduction Atrial fibrillation (AF) affects 1% of the general population and its prevalence in patients referred for mitral valve surgery is up to 70%–80% w1–3x. The therapeutic goal in the treatment of AF is to restore mechanical function of the atrium with a physiological atrio-ventricular synchronicity, to reduce the thromboembolic risk and possibly to avoid anticoagulant and antiarrhythmic drugs. The Cox-maze III operation is the gold standard in the treatment of patients with permanent AF w4x. Several modifications of the maze procedure have been created, and the ablation lines are now performed with different sources of energy w4–6x. Bipolar radiofrequency (RF) is to date the most effective way to perform transmural atrial scars for the surgical ablation of AF during open-heart surgery. A complete left and right lesion set has a proven role in improving AF cure rate w5, 7, 8x. Nevertheless, bipolar devices are generally not used to perform the mitral and tricuspid lines. This is because of their clamping feature and their efficacy that could potentially increase the risk of coronary injury. Many surgeons generally prefer either * Corresponding author: Tel.: q39 02-26437102; fax: q39 0226437125. E-mail: [email protected] 2010 European Association for Cardio-thoracic Surgery
to avoid the mitral ablation or to complete such an ablation using adjunctive unipolar devices, thus making the procedure less effective, more expensive and longer. In this context, the most convenient unipolar energy source to combine with bipolar RF is probably cryoablation w9x, which is safe, transmural and now feasible in most countries using resterilizable devices. We have recently reported the safety and the feasibility of the left isthmus line and of tricuspid connecting ablations with a bipolar RF device w10–12x. Here we report the results of a simple, safe and reproducible technique to perform a complete biatrial set of lines, entailing left and right isthmus lines, using bipolar RF or in combination with cryoenergy.
Patients and methods The study population consists of 80 consecutive patients who underwent surgical AF treatment with complete biatrial ablation using bipolar RF as a solo modality between February 2007 and July 2009. In 91% of the cases (73/80 patients), the ablation of the AF was a concomitant procedure (83% of the patients had primary mitral valve disease as the main indication to open-heart surgery), while in seven cases the primary indication to surgery was isolated AF. 1
S. Benussi et al. / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2009.004390 The right ablation lines consisted of a right isthmus ablation alone in 26 patients, of a right isthmus plus anteromedial tricuspid ablation in 20 patients and of a complete maze III set of lines in 34 patients. The type of AF was paroxysmal in three patients (4%), persistent in 17 patients (21%) and permanent in 60 patients (75%).
Surgical technique Transesophageal echocardiography is performed in all patients within 24 h before the surgery to exclude intracavitary thrombosis. When available, coronary angiography is thoroughly considered to discern the specific coronary anatomy. All ablations were carried out using bipolar RF devices: 43% with Cobra Bipolar (Estech Inc, Camino Ramon, CA, USA), 44% with Isolator (Atricure Inc, Cincinnati, OH, USA) and 13% with the BP2 (Medtronic Inc, Minneapolis, MN, USA). Cryoablations on the mitral and/or tricuspid annulus were added in 21 patients. Left atrial ablation (Videos 1–3)
Video 3. Left atrial connecting ablation and left appendage obliteration. After the cardioplegic arrest, the left atrium is opened parallel to the Waterstone groove, the projection of the needle on the posterior mitral annulus is identified and the needle is removed. The mitral ablation line is performed with the proximal part of the clamp intersecting the atriotomy and the tip of the inner jaw biting the posterior mitral annulus. The coronary sinus that passes along the atrial side of the AV groove is thus circumferentially ablated. Such ablation is generally repeated at least once. Two endoepicardial lines are carried out to connect the two encirclings, one on the roof of the left atrium connecting the right superior PV to the left superior PV and one from the inferior part of the atriotomy to the left inferior PV. The last ablation line is performed by clamping the device with one jaw in a left pulmonary vein and the other in the left appendage. After completing the left ablation, the left appendage is meticulously oversewn at its base with a watertight double layer of 4-0 polypropylene (mattress followed by over and over suture).
Before left appendage closure, it is preferable to purge it from air, which may possibly embolize in the case of a residual endoleak. A slight modification of the described left atrial ablation procedure makes the same lesion set feasible with a transseptal incision, when this approach is preferred w15x.
Video 1. Isolation and encircling of pulmonary veins. The encircling ablations of the pulmonary vein (PV) orifices are performed epicardially, usually on-pump. The device is clamped on the antral portion of the atrium, around the PV couple to be isolated. Two or more parallel ablations are normally performed based on tissue thickness and visual fat content and also depending on the platform being used w12–14x.
Video 2. The anatomy of the coronary arteries is then inspected after lifting the fully decompressed beating heart. The coronary-free segment of the atrioventricular (AV) groove between the terminal branch of the right coronary artery and of the circumflex artery is identified. A 20-mm hypodermic needle is placed on the atrial side of the coronary sinus, in order to identify the middle point of such a target area.
2
Right atrial ablation (Videos 4–7)
Video 4. Right atrial ablation. When a complete maze III type lesion set is planned, the right atriotomy is performed perpendicular to the antero-posterior AV groove around the inferior vena cava (IVC) cannulation site. The groove is entered by separating the sulcus fat from the atrial wall and is developed with the scissors by blunt dissection down to the plane of the tricuspid annulus, corresponding to the anterior portion of the posterior leaflet. The right coronary artery is clearly identified by blunt inspection with the scissors and is safely left on the ventricular side of the dissection. Optionally, it may be looped. This part of the procedure may be performed just after cross-clamping, during cardioplegia administration.
S. Benussi et al. / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2009.004390
Video 5. Then the bipolar device is inserted: the tip of the epicardial jaw is sled in the dissected portion of the AV groove, checked for biting the tricuspid, and the ablation is performed. The edge of the atriotomy is tractioned upward while the clamp is forced down in the groove to prevent backsliding of the device during energy deployment. Liberal clamping of the tricuspid leaflets must be avoided to prevent valve impairment.
Video 6. After incision or minimal amputation of the tip of the right appendage, the same type of dissection is carried out on the medial aspect of the right atrium. The blunt dissection is carried out with the scissors following the atrial wall down to the level of the anterior tricuspid annulus. The bipolar device is positioned with the external jaw following the dissected pathway down until the internal jaw intersected the tricuspid annulus at the level of the medial portion of the anterior leaflet. An additional endo-epicardial ablation is performed from the appendage incision towards the main atriotomy.
Video 8. Usually two (possibly simultaneous) cryoablations are deployed endocardially on the mitral annulus and on the corresponding epicardial aspect, to fully ablate the coronary sinus. This last ablation should be cautiously pondered in presence of a left dominant coronary artery.
Cryoablation is used to complete the lesion set when clamping the mitral annulus is deemed unfeasible (adhesion, thick AV tissue, annular calcifications) or unsafe (left dominant coronary system or it is impossible to visually assess coronary distribution, such as via a thoracotomy approach) or for any other reasons based on the surgeon’s preference (Video 8). Cryoablation on the tricuspid annulus is generally not necessary, but when preferred to bipolar RF it is preceded by the same AV groove dissection with right coronary artery dislocation to protect the vessel from possible cryothermal injury w16x. After weaning from the pump, possible endoleaks across the left appendage suture line are ruled out with transesophageal echocardiography. Postoperative management and follow-up Perioperative antiarrhythmic prophylaxis with cordarone was administered for three to six months in the absence of contraindications. Follow-up was complete in 100% of the cases.
Video 7. The right atriotomy is then connected with the inferior vena cava during a short period of snare releasing and with the superior vena cava (SVC) in an endo-epicardial fashion. While the SVC should be ablated at its dorsal aspect to decrease the risk of sinus node dysfunction, the IVC is better addressed by clamping ventrally to prevent possible phrenic nerve biting.
When a simpler right atrial set of lines is opted for (in the case of a small right atrium, recent onset or paroxysmal AF, or unwillingness to possibly increase postoperative pacemaker implantation) and only a cavo-tricuspid ablation is planned, a standard right atriotomy parallel to the AV groove is generally preferred.
Clinical evaluation, standard 12 leads ECG, Holter and transthoracic echocardiography monitoring were performed three, six and 12 months after the operation in our outpatient clinic dedicated to the surgical treatment of arrhythmias. Statistical analysis Statistical analysis has been conducted using the JMP 7.0 software (SAS Institute Inc, NC, USA). Continuous variables are presented as mean"SD and categorical variables are expressed as percentages. Univariable comparisons have been performed either with the paired t-test or ANOVA for parametric or the Wilcoxon test for non-parametric continuous data and likelihood ratio for categorical data. 3
S. Benussi et al. / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2009.004390
Results Preoperative demographic and echocardiographic data are detailed in Table 1 and the open-heart procedures of the study group are showed in Table 2. Procedural success was 100% and no complications were recorded intraoperatively. In-hospital (30-day) mortality was 0%. No cases of myocardial ischaemia were observed and one major bleeding requiring surgical revision occurred. The incidence of stroke was 0% and 5% of the patients (4/80 patients) required permanent pacemaker implantation, with no differences depending on the type of right ablation lines. The median length of hospital stay was 7; 6 to 12 days, without any difference between RF ablation alone and cryoablation plus RF. Follow-up was 100% complete. At six months, the incidence of sinus rhythm (SR) was 84% in patients Table 1. Preoperative data Patients (n) Male/female Age at surgery (years) NYHA functional class • NYHA I (patients) • NYHA II (patients) • NYHA III (patients) • NYHA IV (patients) Ejection fraction (%)* LVEDD (mm) Left atrial volume (ml) Type of AF • Paroxysmal (patients) • Persistent (patients) • Permanent (patients) Duration of AF (months)*
80 40/40 64"11 18 (22%) 43 (54%) 15 (19%) 4 (5%) 60; 50–60 54"9 140"54 3 (4%) 17 (21%) 60 (75%) 35; 8–89
Values are expressed as number and (percentage). *Data are not normally distributed, so variables are expressed as: median; first quartile–third quartile. NYHA, New York Heart Association; LVEDD, left ventricle enddiastolic diameter; AF, atrial fibrillation. Table 2. Associated pathology Mitral repair Mitral replacement • Biological • Mechanical Tricuspid annuloplasty Tricuspid replacement CABG Aortic valve replacement • Biological • Mechanical Other procedures Values are expressed as number and (percentage). CABG, coronary aortic bypass grafting.
4
35 (44%) 32 (40%) 9 (28%) 23 (72%) 46 (58%) 2 (3%) 9 (11%) 10 (13%) 4 (40%) 6 (60%) 7 (9%)
ablated with RF alone and 81% in patients treated with cryoablation plus RF (Ps0.9). No cases of atrial flutter were reported during followup. Freedom from antiarrhythmic drugs (class I and III) was 60% at last follow-up. Two patients died during follow-up, one from stroke and one from acute myocardial infarction. No major bleedings due to oral anticoagulation were reported at follow-up.
Discussion Bipolar RF has become the most popular device in the field of open-heart ablation, because of its safety (only the clamped tissue can be significantly heated and collateral damage is unlikely) and its efficacy in yielding complete tissue penetration of the lesions w17, 18x. However, coronary injury has been described after ablation with all sorts of energy sources, prompting reluctance towards performing the connecting line to the mitral and the tricuspid annuli with a bipolar clamp w19, 20x. When dealing with persistent AF, concomitant left atrial ablation must entail connecting lines between the encirclings and most importantly to the mitral annulus, since simple PV isolation has been related to poorer SR recovery rate and a higher incidence of left flutter w9, 10, 17x. Similarly, a recent meta-analysis indicated the addition of right atrial ablations to significantly improve rhythm outcome of concomitant ablation surgery w21x. We recently reported two simple and safe techniques to perform all left and right atrial ablations with a single bipolar device, pointing out the importance of tailoring accurately the route of the mitral and tricuspid lines on the individual coronary anatomy w10, 11x. The same approach can easily be performed through a transseptal access to the left atrium w15x. Our clinical experience shows that a complete biatrial ablation with bipolar device is feasible and safe: we did not record any complication related to AV groove ablation or postoperative myocardial ischaemia and only one major bleeding event occurred. The results of our series were actually satisfactory with a freedom from AF at six months after surgery )80%. A complete biatrial Cox-maze III set lesion can be safely performed with bipolar radiofrequency as a solo modality, with satisfactory perioperative and longterm results in terms of restoration of SR. This is particularly cost-effective when and where resterilizable unipolar devices are not available. When clamping on
S. Benussi et al. / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2009.004390 the mitral annulus or on the tricuspid annulus is deemed unsafe, unfeasible or otherwise undesired, cryoablation may be used to complete the isthmus lines with comparable safety and excellent results.
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