doi:10.1510/mmcts.2007.002758
The Cox-Maze IV procedure for lone atrial fibrillation Ralph J. Damiano Jra,1,*, Marci Baileyb a
Cardiac Surgery, Washington University School of Medicine, Barnes-Jewish Hospital, St. Louis, MO, USA b
Clinical Research Nurse Specialist, Washington University School of Medicine, Barnes-Jewish Hospital, St. Louis, MO, USA Numerous devices are being used for the ablation of atrial fibrillation. All of the technologies used appropriately can be effective in the clinical situation. At our institution, we have favored bipolar radiofrequency ablation. Numerous experimental studies in our laboratory have shown that these devices provide reliable lesion transmurality and safety. We also have utilized cryosurgery at the valve annuli. These technologies have been used to replace most of the incisions of the Cox-Maze procedure. This new operation has been termed the CoxMaze IV, and can be performed either through a median sternotomy or through a right minithoracotomy. This modified operation requires only two small atriotomies. The right heart ablations can be performed on the beating heart, but left atrial lesions are created on the arrested heart. The left atrial appendage is always amputated or excluded. In our hands, this procedure has been able to cure over 90% of patients, both with paroxysmal and permanent atrial fibrillation.
Keywords: Anti-arrhythmia surgery; Atrial fibrillation; Bipolar radiofrequency ablation Introduction Atrial fibrillation (AF) affects more than 2.2 million persons in the US, with an increased incidence within the elderly population w1x. The presence of AF is an independent risk factor for stroke. When compared with AF-free patients, there is a five-fold increase in the incidence of stroke w2x. Even after adjusting for preexisting cardiovascular conditions, AF is associated with a 1.5- to 1.9-fold increase in mortality risk w3x. Additional consequences of AF include increased Ralph J. Damiano Jr discloses that he has a financial relationship with AtriCure, Inc., Guidant, CV Medical and that he is a consultant for Edwards, Medtronic and Cryocath. *Corresponding author: Cardiothoracic Surgery, Campus Box 8234, 660 South Euclid Avenue, St. Louis, MO 63110, USA Tel.: q1-314-362 7327; fax: q 1-314-747 0917. E-mail: [email protected] 1
2007 European Association for Cardio-thoracic Surgery
hospitalizations, thromboembolic events, hemodynamic compromise, and decreased quality of life w4x. In addition to the increased patient morbidity and mortality, AF is associated with significant hospital costs w5x. Overview of the available technologies There are many controversies in the treatment of lone atrial fibrillation surgically. They center around which ablation technology should be used, and the appropriate lesion set for the individual patient (Photo 1). The ideal minimally invasive procedure would be able to be performed off-pump, on the beating heart without cardiopulmonary bypass. Unfortunately, epicardial thermal ablation on the beating heart has been difficult because of the heat sink of the circulating blood 1
R.J. Damiano Jr and M. Bailey / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2007.002758
Surgical technique These procedures can be performed through either a median sternotomy or a small right thoracotomy similar to that used for mitral valve surgery, but do require cardiopulmonary bypass w10, 11x. This operation is termed the Cox-Maze IV (Schematic 1), and basically it has all the lesions of the Maze III and does include boxing out the entire posterior left atrium. There are only two small atriotomies. Unipolar technology (cryoablation) is used at the valve annuli. The left atrial appendage is amputated or oversewn. The procedure will be demonstrated in a patient with lone atrial fibrillation. Photo 1. Overview of devices available for OPCAB and on-pump surgical ablation. (The part showing the bipolar radiofrequency device is reproduced from Ref. w10x with permission from Elsevier Science.)
pool. Experimentally, both cold and heat-based unipolar energy sources (i.e. radiofrequency, microwave, laser, cryosurgery) have had difficulty creating reliable transmural lesions on the beating heart. High-frequency ultrasound has been reported to be able to achieve transmurality; however, there has not been any objective testing of this technology in this setting. Current shortcomings of unipolar ablation technology also include no indication of lesion transmurality. This has led to confusion regarding appropriate ablation times, and often to multiple and/or prolonged ablations which can lead to collateral injury, either to coronary arteries or the esophagus. To overcome some of these shortcomings, bipolar radiofrequency ablation devices have been employed. These are able to reliably create transmural lesions on the beating heart w6–9x. However, they can only perform a limited lesion set (i.e. pulmonary vein isolation) on the beating heart. While this may be adequate in some patients with paroxysmal atrial fibrillation, results have been poor in patients with organic heart disease and/or permanent atrial fibrillation. Also, a truly endoscopic approach has been difficult with these bulky clamps. To perform more extensive lesion sets, it will be necessary to employ adjunctive cryothermia. In order to perform a full Cox-Maze lesion set, we still employ cardiopulmonary bypass for these reasons. Our initial approach at Washington University has been to simplify the Maze III procedure by replacing most of the incisions with transmural ablation lines using bipolar radiofrequency, while preserving the entire lesion set. 2
• 57-year-old female. • 18 months history of paroxysmal atrial fibrillation. • Diagnosed with coronary artery fistula from the LAD to the pulmonary artery. • Echocardiogram: left atrial diameter of 4.6 cm and no valvular disease. • Cardiac catheterization: coronary artery from fistula from LAD to pulmonary artery. No atherosclerotic disease. The procedure is started on cardiopulmonary bypass, but with the heart beating. Bicaval cannulation is performed, and the left and right pulmonary veins are dissected (Videos 1 and 2). The conductivity is tested by pacing both left and right pulmonary veins (Video 2). Bipolar ablation device is applied to the right PVs, taking care to include a generous portion of the left atrium in the clamp.
Schematic 1. Lesions, which have to be set for a complete ablation of atrial fibrillation in the newly developed, further version of Cox procedure, now called Cox-Maze IV. (Reproduced from Ref. w12x with permission from Elsevier Science.)
R.J. Damiano Jr and M. Bailey / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2007.002758
Video 1. Dissection of the pulmonary veins (PVs) until clear view of left atrial wall is obtained. On the left, the Marshall’s fold is divided and tape is passed around left PV.
Video 2. PV pacing threshold is determined on the left and right superior and inferior PVs, using a hand-held bipolar pacing electrode. Bipolar ablation device is applied to the right PVs, taking care to include a generous portion of the left atrium in the clamp.
The adequacy of ablation is verified by stimulation of the ablated area (Video 3). Bipolar ablation device is now applied to the left PVs, with an assistant exercising traction on the umbilical tape previously passed around left PV. Again, a generous portion of the left atrium is grasped with the clamp. Umbilical tape is divided and removed prior to applying ablation radiofrequency (Video 4). Right atrial lesions (Video 5) set is done through a small incision at the base of the right appendage and through a single right atriotomy to replicate the maze lesions (Schematic 2). Ablation lines are taken to the superior and inferior vena cava. We make a purse string suture in the right atrium and take the ablation lines down to the tricuspid annulus at the 10 and 2 o’clock position, and these can be done with either bipolar clamping, combined with linear cryolesions with the beating heart (Videos 6–8).
Video 3. Adequacy of ablation is verified by the inability to stimulate the atrium from the right PVs; the lesion at the entrance of the right PV is also shown.
Video 4. Bipolar ablation device is now applied to the left PVs, with an assistant exercising traction on the umbilical tape previously passed around left PV. Again, a generous portion of the left atrium is grasped with the clamp. Umbilical tape is divided and removed prior to applying ablation radiofrequency. The ablation is verified by pacing, as on the right side.
Video 5. Small atriotomy is performed at the base of right atrial appendage, after placing a purse string suture around the planned incision, and a bipolar ablation device is introduced. It is placed across atrial free wall and ablation is performed.
The left atrial lesion set (Schematic 3) is shown here through a standard left atriotomy. At this point, and with the heart still beating, an aiming point is marked with methylene blue on the coronary sinus from the outside (Video 9). The heart is arrested by cold cardioplegia, left atrium is opened and a bipolar radiofrequency is applied to produce a lesion which is directed towards left pulmonary veins, and (in larger atria) a second lesion is
Schematic 2. Set of lesions in right atrium.
3
R.J. Damiano Jr and M. Bailey / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2007.002758
Video 6. Vertical atriotomy is performed and extended to the atrial septum and to the tricuspid valve, and a cryoprobe is placed towards tricuspid annulus. Cryoablation (2 min, y608C) is performed, and a bipolar ablation probe is applied posteriorly, towards superior vena cava, taking care to stay well behind the sinus node.
Schematic 3. Lesion set in the left atrium: a combination of surgical incisions, radiofrequency and cryo lesions. (Reproduced from Ref. w10x after slight modification with permission from Elsevier Science.) Video 7. Bipolar device is rotated inferiorly and a similar lesion is placed on the lateral wall of the right atrium, extending into the inferior vena cava, through the umbilical tape encircling the vena cava.
Video 9. Coronary sinus is marked with methylene blue at the point between left and right coronary circulation.
Video 8. Second cryolesion is set from the right atrial appendage to the tricuspid annulus in the same mode as before.
made in the dome of the left atrium connecting with the left superior pulmonary vein (Video 10). The next lesion is again set by a bipolar device (Video 11), and is complemented by cryolesions set both from inside and outside of the left atrium, ablating tissue around coronary sinus (Video 12). Final lesion is set across the atrial septum, extending into the fossa ovalis (Video 13). The operation is finished by amputating the left atrial appendage and performing the last bipolar lesions over the left upper pulmonary vein (Video 14). Pulmonary vein isolation, which is still occasionally performed, and can be done without cardiopulmonary bypass and through a small thoracotomy, uses a set of variable lesions (Schematic 4), aimed at the electrical isolation of the particular arrhythmogenic area at the entrance of pulmonary veins into the right atrium. 4
Video 10. With heart arrested by cold cardioplegia, left atrium is opened and a bipolar radiofrequency is applied to produce a lesion, which is directed towards left pulmonary veins, and (in larger atria) a second lesion is made in the dome of the left atrium connecting with the left superior pulmonary vein.
Results As of May 2007, we have used bipolar radiofrequency ablation in over 200 patients. The Cox-Maze IV procedure was selected in 167 cases (77%). We have also performed 34 pulmonary vein isolation procedures and 15 limited (right atrial or left atrial) lesion sets. The freedom from AF recurrence in
R.J. Damiano Jr and M. Bailey / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2007.002758
Video 11. Bipolar device is introduced into the left atrium and a lesion is set in the posterior wall, pointing towards the marked point on the coronary sinus. Usually, the device is too short, and its end is marked on endocardium with methylene blue.
Schematic 4. Various lesions employed in OPCAB atrial vein isolation.
Video 12. Additional cryolesions are set between the apex of the bipolar lesion and the mitral annulus, and usually complemented with another cryolesion set epicardially on the marked point on the coronary sinus.
Graph 1. Freedom from AF recurrence in the Cox-Maze IV procedure.
Video 13. Final lesion is set across the atrial septum, extending into the fossa ovalis.
pensity scores w12x. There was no significant difference in the freedom from AF at 3, 6, or 12 months between groups. Our early experience with bipolar radiofrequency ablation suggests that this technology can be used to replace the surgical incisions and simplify the operation, while maintaining excellent results. The lone Cox-Maze procedure has been performed in over 60 patients using bipolar radiofrequency as the energy source. Of these, 33% of patients came to our institution with a history of previous catheter ablation. The mean aortic cross-clamp time for a lone Cox-
Video 14. Left atrial appendage is amputated and another bipolar lesion is set on the left pulmonary vein, completing the Cox-Maze IV procedure, and atrial appendage is over sewn.
our entire Cox-Maze IV series is 91.5%, 90.3%, and 92.2% at 3, 6, and 12 months, respectively (Graph 1). Using propensity analysis, our institution compared the surgical outcomes of patients undergoing the original cut-and-sew technique (Cox-Maze III procedure) with those patients undergoing the Cox-Maze IV procedure by matching each group based on similar pro-
Graph 2. Freedom from AF recurrence in the lone Cox-Maze IV.
5
R.J. Damiano Jr and M. Bailey / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2007.002758 Table 1. Recent success rates of catheter ablation for AF Study
Year
Patients
Parox (%)
AF free (off drugs) (%)
Follow-up (days)
Haissaguerre et al. Mansour et al. Marrouche et al. Oral et al. Pappone et al.
2004 2004 2003 2003 2003
70 40 259 40 589
N/A 80 51 100 69
79 75 87 88 79
210 330 347 365 861
Maze IV procedure was significantly less than our Cox-Maze III experience (35"15 min vs. 93"34 min, P-0.001). Our freedom from AF recurrence in the lone Cox-Maze IV group is 96.2%, 92.5%, and 92.8% at 3, 6, and 12 months, respectively (Graph 2).
is imperative that we become more electrophysiologically sophisticated in the future in order to improve our success rates. Ideally, our operation would be tailored to the mechanism of atrial fibrillation in individual patients.
Discussion
References
Surgical results with lone AF have to be viewed in comparison with those seen following catheter ablation (Table 1). However, it is misguided to view surgery as competitive with catheter-based procedures. We need to work together with electrophysiologists to define the indications for surgery, refine our procedures, improve intraoperative electrophysiological testing, and develop consensus for reporting our results.
w1x Thom T, Haase N, Rosamond W, Howard VJ, Rumsfeld J, Manolio T, Zheng ZJ, Felgal K, O’Donnell C, Kittner S, Lloyd-Jones D, Goff DC Jr, Hong Y, Adams R, Friday G, Furie K, Gorelick P, Kissela B, Marler J, Meigs J, Roger V, Sidney S, Sorlie P, Steinberger J, Wasserthiel-Smoller S, Wilson M, Wolf P. Heart disease and stroke statistics—2006 update: a report from the American Heart Association Statistics Committee and Stroke Statistics Subcommittee. Circulation 2006;113:e85–e151. w2x Wolf PA, Abbott RD, Kannel WB. Atrial fibrillation as an independent risk factor for stroke: the Framingham study. Stroke 1991;22:983–988. w3x Benjamin EJ, Wolf PA, D’Agostino RB, Silbershatz H, Kannel WB, Levy D. Impact of atrial fibrillation on the risk of death: the Framingham heart study. Circulation 1998;98:946–952. w4x Valderrama AL, Dunbar SB, Mensah GA. Atrial fibrillation: public health implications. Am J Prev Med 2005;29:75–80. w5x Wattigney WA, Mensah GA, Croft JB. Increasing trends in hospitalization for atrial fibrillation in the United States, 1985 through 1999: implications for primary prevention. Circulation 2003;108:711–716. w6x 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. w7x Prasad S, Maniar HS, Schuessler RB, Damiano RJ Jr. Chronic transmural atrial ablation using bipolar radiofrequency energy on the beating heart. J Thorac Cardiovasc Surg 2002;124:708– 713. w8x Gaynor SL, Ishii Y, Diodato MD, Prasad S, Barnett K, Damiano NR, Wickline SA, Schuessler RB,
In the long run, the success of catheter ablation will likely increase surgical referrals, particularly if it can lead to a more interventional approach to this arrhythmia. Many internists still believe that these patients should only have rate control and anticoagulation. When electrophysiologists convince the medical community that catheter ablation is appropriate therapy for medically refractory atrial fibrillation, it will also provide justification for a surgical approach, particularly in those patients who have failed catheter ablation or in whom the electrophysiologists elect not to treat. In conclusion, surgery will play a role in the treatment of lone atrial fibrillation in the future. The development of minimally invasive operations will increase that role. It must be mentioned that the present ablation technology is far from perfect, and has limited our progress. The development of effective unipolar energy sources that can create full lesion sets will be a major advance. Moreover, our understanding of atrial fibrillation is still at a relatively primitive stage. Few patients are referred with precise definition of the mechanism of their atrial fibrillation. There is a great deal of data to suggest that the type of atrial fibrillation (i.e. paroxysmal vs. persistent) does not imply mechanism. There are patients with paroxysmal AF who have neither focal nor pulmonary vein triggers. It 6
R.J. Damiano Jr and M. Bailey / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2007.002758 Damiano RJ Jr. Successful performance of the Cox-Maze procedure on the beating heart using bipolar radiofrequency ablation: a feasibility study in animals. Ann Thorac Surg 2004;78:1671– 1677. w9x Melby SJ, Gaynor SL, Lubahn JG, Lee AM, Rahgozar P, Caruthers SD, Williams TA, Schuessler RB, Damiano RJ Jr. Efficacy and safety of right and left atrial ablations on the beating heart using irrigated bipolar radiofrequency energy: a chronic animal study. J Thorac Cardiovasc Surg 2006;132:853–860. w10x Gaynor SL, Diodato MD, Prasad SM, Ishii Y, Schuessler RB, Bailey MS, Damiano NR, Bloch JB, Damiano RJ Jr. A prospective, single center
clinical trial of a modified Cox-Maze procedure using bipolar radiofrequency ablation. J Thorac Cardiovasc Surg 2004;128:535–542. w11x Melby SJ, Zierer A, Voeller RK, Lall S, Bailey MS, Moon MR, Huddleston CB, Crabtree TD, 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. w12x Lall SC, Melby SJ, Voeller RK, Zierer A, Bailey MS, Guthrie TJ, Moon MR, Moazami N, Lawton JS, Damiano RJ Jr. The impact of ablation technology on surgical outcomes following the Cox-Maze procedure: a propensity study. J Thorac Cardiovasc Surg 2007;133:389–396.
7
The Cox-Maze IV procedure for lone atrial fibrillation Ralph J. Damiano Jra,1,*, Marci Baileyb a
Cardiac Surgery, Washington University School of Medicine, Barnes-Jewish Hospital, St. Louis, MO, USA b
Clinical Research Nurse Specialist, Washington University School of Medicine, Barnes-Jewish Hospital, St. Louis, MO, USA Numerous devices are being used for the ablation of atrial fibrillation. All of the technologies used appropriately can be effective in the clinical situation. At our institution, we have favored bipolar radiofrequency ablation. Numerous experimental studies in our laboratory have shown that these devices provide reliable lesion transmurality and safety. We also have utilized cryosurgery at the valve annuli. These technologies have been used to replace most of the incisions of the Cox-Maze procedure. This new operation has been termed the CoxMaze IV, and can be performed either through a median sternotomy or through a right minithoracotomy. This modified operation requires only two small atriotomies. The right heart ablations can be performed on the beating heart, but left atrial lesions are created on the arrested heart. The left atrial appendage is always amputated or excluded. In our hands, this procedure has been able to cure over 90% of patients, both with paroxysmal and permanent atrial fibrillation.
Keywords: Anti-arrhythmia surgery; Atrial fibrillation; Bipolar radiofrequency ablation Introduction Atrial fibrillation (AF) affects more than 2.2 million persons in the US, with an increased incidence within the elderly population w1x. The presence of AF is an independent risk factor for stroke. When compared with AF-free patients, there is a five-fold increase in the incidence of stroke w2x. Even after adjusting for preexisting cardiovascular conditions, AF is associated with a 1.5- to 1.9-fold increase in mortality risk w3x. Additional consequences of AF include increased Ralph J. Damiano Jr discloses that he has a financial relationship with AtriCure, Inc., Guidant, CV Medical and that he is a consultant for Edwards, Medtronic and Cryocath. *Corresponding author: Cardiothoracic Surgery, Campus Box 8234, 660 South Euclid Avenue, St. Louis, MO 63110, USA Tel.: q1-314-362 7327; fax: q 1-314-747 0917. E-mail: [email protected] 1
2007 European Association for Cardio-thoracic Surgery
hospitalizations, thromboembolic events, hemodynamic compromise, and decreased quality of life w4x. In addition to the increased patient morbidity and mortality, AF is associated with significant hospital costs w5x. Overview of the available technologies There are many controversies in the treatment of lone atrial fibrillation surgically. They center around which ablation technology should be used, and the appropriate lesion set for the individual patient (Photo 1). The ideal minimally invasive procedure would be able to be performed off-pump, on the beating heart without cardiopulmonary bypass. Unfortunately, epicardial thermal ablation on the beating heart has been difficult because of the heat sink of the circulating blood 1
R.J. Damiano Jr and M. Bailey / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2007.002758
Surgical technique These procedures can be performed through either a median sternotomy or a small right thoracotomy similar to that used for mitral valve surgery, but do require cardiopulmonary bypass w10, 11x. This operation is termed the Cox-Maze IV (Schematic 1), and basically it has all the lesions of the Maze III and does include boxing out the entire posterior left atrium. There are only two small atriotomies. Unipolar technology (cryoablation) is used at the valve annuli. The left atrial appendage is amputated or oversewn. The procedure will be demonstrated in a patient with lone atrial fibrillation. Photo 1. Overview of devices available for OPCAB and on-pump surgical ablation. (The part showing the bipolar radiofrequency device is reproduced from Ref. w10x with permission from Elsevier Science.)
pool. Experimentally, both cold and heat-based unipolar energy sources (i.e. radiofrequency, microwave, laser, cryosurgery) have had difficulty creating reliable transmural lesions on the beating heart. High-frequency ultrasound has been reported to be able to achieve transmurality; however, there has not been any objective testing of this technology in this setting. Current shortcomings of unipolar ablation technology also include no indication of lesion transmurality. This has led to confusion regarding appropriate ablation times, and often to multiple and/or prolonged ablations which can lead to collateral injury, either to coronary arteries or the esophagus. To overcome some of these shortcomings, bipolar radiofrequency ablation devices have been employed. These are able to reliably create transmural lesions on the beating heart w6–9x. However, they can only perform a limited lesion set (i.e. pulmonary vein isolation) on the beating heart. While this may be adequate in some patients with paroxysmal atrial fibrillation, results have been poor in patients with organic heart disease and/or permanent atrial fibrillation. Also, a truly endoscopic approach has been difficult with these bulky clamps. To perform more extensive lesion sets, it will be necessary to employ adjunctive cryothermia. In order to perform a full Cox-Maze lesion set, we still employ cardiopulmonary bypass for these reasons. Our initial approach at Washington University has been to simplify the Maze III procedure by replacing most of the incisions with transmural ablation lines using bipolar radiofrequency, while preserving the entire lesion set. 2
• 57-year-old female. • 18 months history of paroxysmal atrial fibrillation. • Diagnosed with coronary artery fistula from the LAD to the pulmonary artery. • Echocardiogram: left atrial diameter of 4.6 cm and no valvular disease. • Cardiac catheterization: coronary artery from fistula from LAD to pulmonary artery. No atherosclerotic disease. The procedure is started on cardiopulmonary bypass, but with the heart beating. Bicaval cannulation is performed, and the left and right pulmonary veins are dissected (Videos 1 and 2). The conductivity is tested by pacing both left and right pulmonary veins (Video 2). Bipolar ablation device is applied to the right PVs, taking care to include a generous portion of the left atrium in the clamp.
Schematic 1. Lesions, which have to be set for a complete ablation of atrial fibrillation in the newly developed, further version of Cox procedure, now called Cox-Maze IV. (Reproduced from Ref. w12x with permission from Elsevier Science.)
R.J. Damiano Jr and M. Bailey / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2007.002758
Video 1. Dissection of the pulmonary veins (PVs) until clear view of left atrial wall is obtained. On the left, the Marshall’s fold is divided and tape is passed around left PV.
Video 2. PV pacing threshold is determined on the left and right superior and inferior PVs, using a hand-held bipolar pacing electrode. Bipolar ablation device is applied to the right PVs, taking care to include a generous portion of the left atrium in the clamp.
The adequacy of ablation is verified by stimulation of the ablated area (Video 3). Bipolar ablation device is now applied to the left PVs, with an assistant exercising traction on the umbilical tape previously passed around left PV. Again, a generous portion of the left atrium is grasped with the clamp. Umbilical tape is divided and removed prior to applying ablation radiofrequency (Video 4). Right atrial lesions (Video 5) set is done through a small incision at the base of the right appendage and through a single right atriotomy to replicate the maze lesions (Schematic 2). Ablation lines are taken to the superior and inferior vena cava. We make a purse string suture in the right atrium and take the ablation lines down to the tricuspid annulus at the 10 and 2 o’clock position, and these can be done with either bipolar clamping, combined with linear cryolesions with the beating heart (Videos 6–8).
Video 3. Adequacy of ablation is verified by the inability to stimulate the atrium from the right PVs; the lesion at the entrance of the right PV is also shown.
Video 4. Bipolar ablation device is now applied to the left PVs, with an assistant exercising traction on the umbilical tape previously passed around left PV. Again, a generous portion of the left atrium is grasped with the clamp. Umbilical tape is divided and removed prior to applying ablation radiofrequency. The ablation is verified by pacing, as on the right side.
Video 5. Small atriotomy is performed at the base of right atrial appendage, after placing a purse string suture around the planned incision, and a bipolar ablation device is introduced. It is placed across atrial free wall and ablation is performed.
The left atrial lesion set (Schematic 3) is shown here through a standard left atriotomy. At this point, and with the heart still beating, an aiming point is marked with methylene blue on the coronary sinus from the outside (Video 9). The heart is arrested by cold cardioplegia, left atrium is opened and a bipolar radiofrequency is applied to produce a lesion which is directed towards left pulmonary veins, and (in larger atria) a second lesion is
Schematic 2. Set of lesions in right atrium.
3
R.J. Damiano Jr and M. Bailey / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2007.002758
Video 6. Vertical atriotomy is performed and extended to the atrial septum and to the tricuspid valve, and a cryoprobe is placed towards tricuspid annulus. Cryoablation (2 min, y608C) is performed, and a bipolar ablation probe is applied posteriorly, towards superior vena cava, taking care to stay well behind the sinus node.
Schematic 3. Lesion set in the left atrium: a combination of surgical incisions, radiofrequency and cryo lesions. (Reproduced from Ref. w10x after slight modification with permission from Elsevier Science.) Video 7. Bipolar device is rotated inferiorly and a similar lesion is placed on the lateral wall of the right atrium, extending into the inferior vena cava, through the umbilical tape encircling the vena cava.
Video 9. Coronary sinus is marked with methylene blue at the point between left and right coronary circulation.
Video 8. Second cryolesion is set from the right atrial appendage to the tricuspid annulus in the same mode as before.
made in the dome of the left atrium connecting with the left superior pulmonary vein (Video 10). The next lesion is again set by a bipolar device (Video 11), and is complemented by cryolesions set both from inside and outside of the left atrium, ablating tissue around coronary sinus (Video 12). Final lesion is set across the atrial septum, extending into the fossa ovalis (Video 13). The operation is finished by amputating the left atrial appendage and performing the last bipolar lesions over the left upper pulmonary vein (Video 14). Pulmonary vein isolation, which is still occasionally performed, and can be done without cardiopulmonary bypass and through a small thoracotomy, uses a set of variable lesions (Schematic 4), aimed at the electrical isolation of the particular arrhythmogenic area at the entrance of pulmonary veins into the right atrium. 4
Video 10. With heart arrested by cold cardioplegia, left atrium is opened and a bipolar radiofrequency is applied to produce a lesion, which is directed towards left pulmonary veins, and (in larger atria) a second lesion is made in the dome of the left atrium connecting with the left superior pulmonary vein.
Results As of May 2007, we have used bipolar radiofrequency ablation in over 200 patients. The Cox-Maze IV procedure was selected in 167 cases (77%). We have also performed 34 pulmonary vein isolation procedures and 15 limited (right atrial or left atrial) lesion sets. The freedom from AF recurrence in
R.J. Damiano Jr and M. Bailey / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2007.002758
Video 11. Bipolar device is introduced into the left atrium and a lesion is set in the posterior wall, pointing towards the marked point on the coronary sinus. Usually, the device is too short, and its end is marked on endocardium with methylene blue.
Schematic 4. Various lesions employed in OPCAB atrial vein isolation.
Video 12. Additional cryolesions are set between the apex of the bipolar lesion and the mitral annulus, and usually complemented with another cryolesion set epicardially on the marked point on the coronary sinus.
Graph 1. Freedom from AF recurrence in the Cox-Maze IV procedure.
Video 13. Final lesion is set across the atrial septum, extending into the fossa ovalis.
pensity scores w12x. There was no significant difference in the freedom from AF at 3, 6, or 12 months between groups. Our early experience with bipolar radiofrequency ablation suggests that this technology can be used to replace the surgical incisions and simplify the operation, while maintaining excellent results. The lone Cox-Maze procedure has been performed in over 60 patients using bipolar radiofrequency as the energy source. Of these, 33% of patients came to our institution with a history of previous catheter ablation. The mean aortic cross-clamp time for a lone Cox-
Video 14. Left atrial appendage is amputated and another bipolar lesion is set on the left pulmonary vein, completing the Cox-Maze IV procedure, and atrial appendage is over sewn.
our entire Cox-Maze IV series is 91.5%, 90.3%, and 92.2% at 3, 6, and 12 months, respectively (Graph 1). Using propensity analysis, our institution compared the surgical outcomes of patients undergoing the original cut-and-sew technique (Cox-Maze III procedure) with those patients undergoing the Cox-Maze IV procedure by matching each group based on similar pro-
Graph 2. Freedom from AF recurrence in the lone Cox-Maze IV.
5
R.J. Damiano Jr and M. Bailey / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2007.002758 Table 1. Recent success rates of catheter ablation for AF Study
Year
Patients
Parox (%)
AF free (off drugs) (%)
Follow-up (days)
Haissaguerre et al. Mansour et al. Marrouche et al. Oral et al. Pappone et al.
2004 2004 2003 2003 2003
70 40 259 40 589
N/A 80 51 100 69
79 75 87 88 79
210 330 347 365 861
Maze IV procedure was significantly less than our Cox-Maze III experience (35"15 min vs. 93"34 min, P-0.001). Our freedom from AF recurrence in the lone Cox-Maze IV group is 96.2%, 92.5%, and 92.8% at 3, 6, and 12 months, respectively (Graph 2).
is imperative that we become more electrophysiologically sophisticated in the future in order to improve our success rates. Ideally, our operation would be tailored to the mechanism of atrial fibrillation in individual patients.
Discussion
References
Surgical results with lone AF have to be viewed in comparison with those seen following catheter ablation (Table 1). However, it is misguided to view surgery as competitive with catheter-based procedures. We need to work together with electrophysiologists to define the indications for surgery, refine our procedures, improve intraoperative electrophysiological testing, and develop consensus for reporting our results.
w1x Thom T, Haase N, Rosamond W, Howard VJ, Rumsfeld J, Manolio T, Zheng ZJ, Felgal K, O’Donnell C, Kittner S, Lloyd-Jones D, Goff DC Jr, Hong Y, Adams R, Friday G, Furie K, Gorelick P, Kissela B, Marler J, Meigs J, Roger V, Sidney S, Sorlie P, Steinberger J, Wasserthiel-Smoller S, Wilson M, Wolf P. Heart disease and stroke statistics—2006 update: a report from the American Heart Association Statistics Committee and Stroke Statistics Subcommittee. Circulation 2006;113:e85–e151. w2x Wolf PA, Abbott RD, Kannel WB. Atrial fibrillation as an independent risk factor for stroke: the Framingham study. Stroke 1991;22:983–988. w3x Benjamin EJ, Wolf PA, D’Agostino RB, Silbershatz H, Kannel WB, Levy D. Impact of atrial fibrillation on the risk of death: the Framingham heart study. Circulation 1998;98:946–952. w4x Valderrama AL, Dunbar SB, Mensah GA. Atrial fibrillation: public health implications. Am J Prev Med 2005;29:75–80. w5x Wattigney WA, Mensah GA, Croft JB. Increasing trends in hospitalization for atrial fibrillation in the United States, 1985 through 1999: implications for primary prevention. Circulation 2003;108:711–716. w6x 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. w7x Prasad S, Maniar HS, Schuessler RB, Damiano RJ Jr. Chronic transmural atrial ablation using bipolar radiofrequency energy on the beating heart. J Thorac Cardiovasc Surg 2002;124:708– 713. w8x Gaynor SL, Ishii Y, Diodato MD, Prasad S, Barnett K, Damiano NR, Wickline SA, Schuessler RB,
In the long run, the success of catheter ablation will likely increase surgical referrals, particularly if it can lead to a more interventional approach to this arrhythmia. Many internists still believe that these patients should only have rate control and anticoagulation. When electrophysiologists convince the medical community that catheter ablation is appropriate therapy for medically refractory atrial fibrillation, it will also provide justification for a surgical approach, particularly in those patients who have failed catheter ablation or in whom the electrophysiologists elect not to treat. In conclusion, surgery will play a role in the treatment of lone atrial fibrillation in the future. The development of minimally invasive operations will increase that role. It must be mentioned that the present ablation technology is far from perfect, and has limited our progress. The development of effective unipolar energy sources that can create full lesion sets will be a major advance. Moreover, our understanding of atrial fibrillation is still at a relatively primitive stage. Few patients are referred with precise definition of the mechanism of their atrial fibrillation. There is a great deal of data to suggest that the type of atrial fibrillation (i.e. paroxysmal vs. persistent) does not imply mechanism. There are patients with paroxysmal AF who have neither focal nor pulmonary vein triggers. It 6
R.J. Damiano Jr and M. Bailey / Multimedia Manual of Cardiothoracic Surgery / doi:10.1510/mmcts.2007.002758 Damiano RJ Jr. Successful performance of the Cox-Maze procedure on the beating heart using bipolar radiofrequency ablation: a feasibility study in animals. Ann Thorac Surg 2004;78:1671– 1677. w9x Melby SJ, Gaynor SL, Lubahn JG, Lee AM, Rahgozar P, Caruthers SD, Williams TA, Schuessler RB, Damiano RJ Jr. Efficacy and safety of right and left atrial ablations on the beating heart using irrigated bipolar radiofrequency energy: a chronic animal study. J Thorac Cardiovasc Surg 2006;132:853–860. w10x Gaynor SL, Diodato MD, Prasad SM, Ishii Y, Schuessler RB, Bailey MS, Damiano NR, Bloch JB, Damiano RJ Jr. A prospective, single center
clinical trial of a modified Cox-Maze procedure using bipolar radiofrequency ablation. J Thorac Cardiovasc Surg 2004;128:535–542. w11x Melby SJ, Zierer A, Voeller RK, Lall S, Bailey MS, Moon MR, Huddleston CB, Crabtree TD, 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. w12x Lall SC, Melby SJ, Voeller RK, Zierer A, Bailey MS, Guthrie TJ, Moon MR, Moazami N, Lawton JS, Damiano RJ Jr. The impact of ablation technology on surgical outcomes following the Cox-Maze procedure: a propensity study. J Thorac Cardiovasc Surg 2007;133:389–396.
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