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Ann Thorac Surg 2006;81:1332-1337
© 2006 The Society of Thoracic Surgeons
s Caynak, MDDepartment of Cardiac Surgery, Florence Nightingale Hospital, Istanbul, Turkey
Accepted for publication September 30, 2005.
* Address correspondence to Dr Akpinar, Department of Cardiac Surgery, Florence Nightingale Hospital, Abidei Hurriyet Cad. No. 290 Sisli, Istanbul, PB80220, Turkey (Email: belhanakpinar{at}gmail.com).
| Dr Akpinar discloses a financial relationship with Medtronic.
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Abstract |
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 Top Abstract IntroductionMaterial and MethodsResultsCommentReferences |
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METHODS: Thirty-three patients underwent the combined procedure. Mean age was 62.34 ± 8.20 years; there were 12 female and 21 male patients. Twenty-one patients were diagnosed as permanent AF (group A) and 12 had paroxysmal AF (group B). After the off-pump revascularization patients underwent pulmonary vein ablation. Rhythm was evaluated at discharge and at 6 and 12 months' follow-up. Patients in stable sinus rhythm underwent transthoracic echocardiographic examination to evaluate atrial contractility at 6 and 12 months.
RESULTS: There was no operative mortality or major complications. The mean ablation time was 11 ± 3.4 minutes, including multiple applications. At the end of the procedure 84.5% of patients were free of AF. Sinus rhythm was established in 56% (group A, 52%; group B, 58.3%), 70.5% (group A, 58%; group B, 83.3%), and 71% (group A, 59%; group B, 83.3%) of patients at discharge and at 6 and 12 months, respectively (p = 0.249). Biatrial contractility was detected in 71% of group A and 76% of group B patients at 6 months' follow-up. More patients in group A returned to AF during follow-up when compared with group B (p = 0.016). Female sex (odds ratio, 2.1), chronic lung disease (odds ratio, 1.40), left ventricular disfunction (p = 0.016), and hypertension (odds ratio, 2.57) emerged as risk factors for AF recurrence after ablation.
CONCLUSIONS: Concomitant off-pump coronary artery bypass grafting and bipolar radiofrequency ablation was safe and effective. These patients should be considered for adjunctive treatment at the time of off-pump revascularization.
Antiarrhythmic surgery to treat atrial fibrillation (AF) has predominantly been combined with mitral valve disease, and the success of different energy sources in this aspect has been shown [1–3]. Although the presence of AF in patients undergoing coronary artery bypass grafting (CABG) is less than their mitral valve counterparts, this percentage is known to increase with older age, male sex, and depressed left ventricular function [4]. This fact, together with the reality that CABG surgery still constitutes the main bulk of the cardiac surgical workload in most centers, has created a greater interest in concomitant CABG and AF treatment. The clinical introduction of bipolar ablation devices that can be applied epicardially has been a major advance in this field, especially for patients with concomitant coronary artery disease. The notion of performing ablation in a patient undergoing CABG without having to open the left atrium or not using cardiopulmonary bypass seemed to be a valid option [5, 6].
Many groups have previously shown the possibility of establishing sinus rhythm in 75% to 98% of patients with the modified Maze procedure using monopolar radiofrequency (RF) energy [1, 2, 7]. These were series that mostly consisted of mitral valve cases. After these encouraging results we decided to extend our indication for combined RF ablation during off-pump CABG (OPCAB).
This paper shares our experience during OPCAB surgery combined with bipolar irrigated RF ablation and compares the results between patients with permanent and paroxysmal AF who underwent a similar ablation procedure.
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Material and Methods |
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Surgical Procedure
After median sternotomy and opening of the pericardium, the conduits were harvested and heparin was administered. The activated clotting time was monitored and maintained greater than 300 seconds during the procedure. Coronary revascularization was performed before ablation using the Octopus 4 (Medtronic Inc, Minneapolis, MN) tissue stabilizer and Starfish 2 (Medtronic Inc) apical suction device.
The ablation was performed using a bipolar irrigated ablation device (Cardioblate BP, Medtonic Inc). The system consists of a power generator and a bipolar clamp with an irrigation system. Theoretically, the transmurality algorithm allows the device to deliver the energy necessary to complete a transmural lesion, thus giving the surgeon a transmurality feedback.
Right Pulmonary Vein Isolation
After revascularization, the right-sided pulmonary vein isolation is performed first. The right side of the pericardium is suspended with stay sutures. Opening of the right pleural space may be necessary in some cases for exposure. The Starfish 2 suction device is applied on the right ventricle, near the atrioventricular junction, and the heart is slightly tilted to the left. This will facilitate exposure of the right pulmonary veins. This is followed by a blunt dissection around the inferior vena cava and the right inferior pulmonary vein, so that the index finger of the surgeon can encircle the inferior vena cava. Then a plane is developed between the right superior pulmonary vein and the right pulmonary artery. A Dietrich (Aeusclap, Germany) atraumatic clamp is introduced through this plane (jaws closed) and gently introduced toward the inferior pulmonary vein until the edge of the clamp is seen. A rubber tube (16F, Nelaton; Willy Rüsch AG, Kernen, Germany) is fed between the two jaws, the clamp is withdrawn, and both right pulmonary veins are encircled. The rubber tube will serve as a guide while introducing the lower jaw of the bipolar clamp. The rubber tube is then fed into the lower jaw of the bipolar clamp, and the lower jaw is introduced in this plane by pulling the rubber tube until the jaw is visible behind the lower pulmonary vein. Then the jaws are closed and locked, and RF energy is applied. The same procedure is applied from the inferior side; that is, the inferior jaw is introduced between the plane created between the inferior vena cava and the right inferior pulmonary vein and slightly introduced toward the right superior pulmonary vein. The jaws are closed and locked, and ablation is repeated again (Fig 1). To avoid possible pulmonary vein stenosis, the curve of the jaw is directed toward the left atrium and not the pulmonary veins. The malleable electrodes of the Cardioblate BP device allow further flexibility in shaping the device to the target tissue. As the aim is to create a complete conduction block, the right pulmonary veins are paced with two atrial pacemaker wires at a rate of 90 beats per minute after each application, and the ablation process is repeated until a complete electrical block is achieved. In our experience, two to four applications were needed to create a conduction block on the right pulmonary veins.
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Antiarrhythmic Therapy
For patients receiving amiodarone previously, an intravenous dose of 300 mg was administered during the operation. These patients received 500 mg/day intravenous amiodarone in the intensive care unit, followed by oral amiodarone 200 mg/day, which was continued for 4 to 6 months.
Patients who were not taking amiodarone previously received an intravenous dose of 300 mg perioperatively, followed by 900 mg/day perfusion for 2 days. This was followed by an oral dose of 400 mg/day for 1 week and 200 mg/day for 4 to 6 months.
All patients continued to receive warfarin sodium (Coumadin; Eczacbasi Co, Istanbul, Turkey) for 12 months unless there was a contraindication. The drug was discontinued if the patient was in a stable sinus rhythm at the end of 12 months. Otherwise it was continued indefinitely.
Cardioversion
Electrical cardioversion was reserved for patients who were still in AF at the end of 6 months. It is our observation that electrical cardioversion is not very helpful during the first couple of months, and the conversion rate to AF is high.
Interpretation of Data
Data were collected for each patient at the end of the procedure, at discharge, and at 6 and 12 months' follow-up. The surface electrocardiogram was evaluated first at each visit. If this revealed sinus rhythm, a 24-hour Holter monitoring was performed. This was followed by a transthoracic echocardiographic examination to assess atrial contraction. A 48-hour Holter monitoring was performed at 12 months to assess the stability of the sinus rhythm.
Statistical Analysis
Statistical calculations were performed using the GraphPad Prisma V.3 program for Windows (GraphPad Software, San Diego, CA). All values were expressed as mean ± standard deviation. The Mann-Whitney U test was used for comparing continuous variables, and Fisher's exact test was performed during the evaluation of qualitative data. A p value less than 0.05 was considered to be statistically significant with a 95% confidence limit.
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Results |
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Overall, 84.5% of patients were either in sinus rhythm or atrial pacing, and 15.5% remained in AF at the end of the procedure. Sinus rhythm was established in 56% (group A, 52.4%; group B, 58.3%), 70.5% (group A, 58%; group B, 83.3%), and 71% (group A, 59%; group B, 83.3%) of patients at discharge and at 6 and 12 months' follow-up (Table 2). All patients were discharged without any serious complications. A transthoracic echocardiographic examination was performed in patients with stable sinus rhythm at 6 and 12 months. Seventy-one percent of patients in group A and 76% of patients in group B had recovered atrial contractions at 6 months. At 12 months 74% of patients in group A and 89% of patients in group B had atrial contractions. The rhythm difference between groups A and B did not reach statistical significance at any stage during follow-up (p = 0.249). During the follow-up, more patients in group A returned to AF(p = 0.016). Female sex (odds ratio, 2.1), existence of chronic obstructive lung disease (odds ratio, 1.4), left ventricular dysfunction (p = 0.016), and hypertension (odds ratio, 2.57) emerged as risk factors for AF recurrence after the ablation procedure.
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Comment |
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TopAbstractIntroductionMaterial and MethodsResultsCommentReferences |
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Although the Cox-Maze procedure remains the gold standard for surgical treatment of AF, the necessity of performing a Maze procedure for all AF patients is a debatable issue. Guden and colleagues [13] and Sueda and associates [14, 15] recently reported that the preclusion of all theoretical macro reentrant circuits is possibly unnecessary and that most patients with AF could be cured with simplified procedures. Geidel and coworkers [9] reported a sinus rhythm restoration rate of 80% in patients with permanent AF after combined on-pump CABG and left-sided RF ablation using bipolar RF energy. Damiano and colleagues [16] reported a sinus rhythm restoration rate of 91% using bipolar RF ablation combined with cryo energy by replicating the Cox-Maze procedure; however they also used cardiopulmonary bypass and most of their patients had lone AF.
The type of AF is probably one of the most prominent factors to determine whether pulmonary vein isolation would be sufficient in patients undergoing OPCAB surgery. According to the concept of Haissaguerre and associates [17], which described that the initiation of AF originated from rapidly firing foci predominantly located inside the pulmonary veins, isolation of both pulmonary veins should be a sufficient basis for a surgical ablation. This is probably true for patients with paroxysmal AF in which the trigger mechanism is responsible for the AF. However, in permanent AF, the left atrial tissue undergoes a complex cellular, morphologic, and electrophysiologic alteration, which can be defined as atrial remodeling. Simple pulmonary vein isolation will probably not be sufficient in these patients, and the Cox-Maze procedure would be more effective (Fig 3).
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Off-pump CABG and bipolar ablative therapy have some disadvantages. Technical difficulties can be encountered in patients with a low left ventricular ejection fraction or an enlarged heart as these patients may not tolerate the procedure hemodynamically. Off-pump CABG is already a challenging procedure in such patients, and further manipulating the heart during ablation and pacing may be problematic. We tried to avoid such patients in this series. A definite contraindication for the approach is the detection of thrombus in the left atrium. Application of the bipolar clamp in the presence of thrombus may not only give a false transmurality signal but also can cause serious thromboembolic events.
We prefer to revascularize the heart before ablation because relieving ischemia first further facilitates manipulating the heart, especially if the patient has critical coronary lesions. However, care should be taken during the left pulmonary vein ablation not to stretch the left internal thoracic artery anastomosis.
Another difficulty with the method is the inability to perform a complete conduction block in one attempt in most patients. Despite the transmurality feedback, one cannot be sure of a conduction block unless pacing of the pulmonary veins is performed, and several applications are usually needed to achieve this goal. We believe this is an important step during off-pump ablation for the time being, and pacing was performed in every patient in this series. However, reapplications may be minimized with the use of second-generation bipolar devices, which are already on the market. New ablation systems with pacing electrodes will further facilitate this procedure in the future.
The surgical treatment of AF has entered a new era with the development of various energy sources and advanced tools that enable surgeons to treat AF using a variety of minimally invasive approaches. Recently there have been studies showing the feasibility of performing totally endoscopic or robotically enhanced pulmonary vein isolation on the beating heart in patients with lone AF [18–20]. On the other hand, current literature on combined OPCAB surgery and ablative therapy is limited. The primary end point of this study is clearly not to make any conclusions based on statistical analyses because of the low number of cases. Much higher volume studies, probably from different centers, will be necessary to accomplish this goal. However, our limited experience suggests that OPCAB surgery and ablative therapy can be performed safely in properly selected cases. Both groups benefited from the procedure in terms of sinus rhythm restoration, but recurrence of AF was more common in the permanent AF group.
Unfortunately, most of the less invasive methods aimed at treating AF are currently focused on pulmonary vein isolation, simply because of technical difficulties when faced to do more. Improvement in current technology that will enable us to perform additional off-pump interatrial lesions may certainly improve our results in the permanent AF group.
This study has some limitations. The number of patients is low despite the fact that statistical analysis was possible. Much higher volume studies, probably from different centers, will be necessary to further evaluate the advantage and disadvantages of this approach. Because most patients came from different centers, preoperative evaluation of atrial transport function was not possible in all cases, and comparison of preoperative and postoperative values of transport function was not possible.
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References |
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TopAbstractIntroductionMaterial and MethodsResultsCommentReferences |
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ndr O. Intraoperative saline irrigated radiofrequency modified maze procedure for atrial fibrillation Ann Thorac Surg 2002;74(Suppl):S1301-S1306.This article has been cited by other articles:
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  M. A. Groh, O. A. Binns, H. G. Burton III, G. L. Champsaur, S. W. Ely, and A. M. Johnson Epicardial Ultrasonic Ablation of Atrial Fibrillation During Concomitant Cardiac Surgery Is a Valid Option in Patients With Ischemic Heart Disease Circulation, September 30, 2008; 118(14_suppl_1): S78 - S82. [Abstract] [Full Text] [PDF]
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 S. K. Balasubramanian, T. Theologou, and I. Birdi Microwave surgical ablation for atrial fibrillation during off-pump coronary artery surgery using total arterial-Y-grafts: an early experience Interactive CardioVascular and Thoracic Surgery, August 1, 2007; 6(4): 447 - 450. [Abstract] [Full Text] [PDF]
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 H. Calkins, J. Brugada, D. L. Packer, R. Cappato, S.-A. Chen, H. J.G. Crijns, R. J. Damiano Jr, D. W. Davies, D. E. Haines, M. Haissaguerre, et al. HRS/EHRA/ECAS Expert Consensus Statement on Catheter and Surgical Ablation of Atrial Fibrillation: Recommendations for Personnel, Policy, Procedures and Follow-Up: A report of the Heart Rhythm Society (HRS) Task Force on Catheter and Surgical Ablation of Atrial Fibrillation Developed in partnership with the European Heart Rhythm Association (EHRA) and the European Cardiac Arrhythmia Society (ECAS); in collaboration with the American College of Cardiology (ACC), American Heart Association (AHA), and the Society of Thoracic Surgeons (STS). Endorsed and Approved by the governing bodies of the American College of Cardiology, the American Heart Association, the European Cardiac Arrhythmia Society, the European Heart Rhythm Association, the Society of Thoracic Surgeons, and the Heart Rhythm Society. Europace, June 1, 2007; 9(6): 335 - 379. [Full Text] [PDF]
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 E. Sagbas, B. Akpinar, I. Sanisoglu, B. Caynak, B. Tamtekin, K. Oral, and B. Onan Video-Assisted Bilateral Epicardial Pulmonary Vein Isolation for the Treatment of Lone Atrial Fibrillation Ann. Thorac. Surg., May 1, 2007; 83(5): 1724 - 1730. [Abstract] [Full Text] [PDF]
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A. E. Saltman Invited commentary Ann. Thorac. Surg., April 1, 2006; 81(4): 1337 - 1338. [Full Text] [PDF]
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