Intraoperative radiofrequency maze ablation for atrial fibrillation: the Berlin                                   modifica...
Intraoperative Radiofrequency Maze Ablation forAtrial Fibrillation: The Berlin ModificationMiralem Pasic, MD, PhD, FETCS, P...
Ann Thorac Surg                                                                                         PASIC ET AL       ...
1486       PASIC ET AL                                                                                                    ...
Ann Thorac Surg                                                                                                PASIC ET AL...
1488     PASIC ET AL                                                                                                     A...
Ann Thorac Surg                                                                                      PASIC ET AL       148...
1490    PASIC ET AL                                                                                                       ...
Ann Thorac Surg                                                                                                PASIC ET AL...
Intraoperative radiofrequency maze ablation for atrial fibrillation: the Berlin                                   modifica...
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  1. 1. Intraoperative radiofrequency maze ablation for atrial fibrillation: the Berlin modificationMiralem Pasic, Peter Bergs, Peter Müller, Michael Hofmann, Onnen Grauhan, Hermann Kuppe and Roland Hetzer Ann Thorac Surg 2001;72:1484-1491The online version of this article, along with updated information and services, is located on the World Wide Web at: The Annals of Thoracic Surgery is the official journal of The Society of Thoracic Surgeons and the Southern Thoracic Surgical Association. Copyright © 2001 by The Society of Thoracic Surgeons. Print ISSN: 0003-4975; eISSN: 1552-6259. Downloaded from by on December 6, 2010
  2. 2. Intraoperative Radiofrequency Maze Ablation forAtrial Fibrillation: The Berlin ModificationMiralem Pasic, MD, PhD, FETCS, Peter Bergs, MD, Peter Muller, MD, ¨Michael Hofmann, MD, Onnen Grauhan, MD, Hermann Kuppe, MD, andRoland Hetzer, MD, PhD, FETCSDeutsches Herzzentrum Berlin, Berlin, Germany Background. The Cox-maze procedure combined with longed the aortic cross-clamp time for 6 to 14 minutesan operation for organic heart disease is highly success- (mean, 11 minutes). Freedom from atrial fibrillation wasful in the elimination of chronic atrial fibrillation. How- 100% intraoperatively, 25% at 1 week after operation (12ever, it prolongs significantly the aortic cross-clamp and of 48 patients), 59% at 1 month postoperatively (16 of 27operating time. In this study, a simplified left atrial maze patients), 64% at 3 months postoperatively (16 of 25procedure, which is a short procedure performed using a patients), and 92% at 6 months postoperatively (12 of 13surgical radiofrequency ablation probe, is added to elective patients). The only predictor of postoperative atrial fi-open heart procedures in patients with atrial fibrillation. brillation was the presence of coronary artery disease Methods. Forty-eight adults with atrial fibrillation (du- (odds ratio, 7.5; 80% confidence interval, 2.24 –25.13).ration, 6 months to 36 years) underwent elective open Conclusions. Intraoperative radiofrequency ablation ofheart operations (isolated valve procedures or coronary the left atrium combined with an operation for organicartery bypass grafting, n 27 patients; combined proce- heart disease effectively eliminates atrial fibrillationdures, n 21 patients) combined with intraoperative without significant prolongation of the aortic cross-clampradiofrequency ablation of the left atrium. The postop- and operative time. The presence of coronary arteryerative follow-up period ranged from 1 to 11 months disease decreases the success rate during the first 6(mean, 4 months). Possible predictors for persistent post- postoperative months.operative atrial fibrillation were determined among 40variables by univariate and multivariate analyses. (Ann Thorac Surg 2001;72:1484 –91) Results. Intraoperative radiofrequency ablation pro- © 2001 by The Society of Thoracic SurgeonsT he Cox-maze procedure is the most effective surgical treatment for patients with chronic atrial fibrillation[1– 4]. The method can be combined with an operation for sions and sutures of the standard maze technique. There is a spectrum of modifications regarding the types of surgical probe used for ablation, modes of applicationorganic heart disease or can be performed as an isolated (endocardial or epicardial), and the directions of thesurgical procedure for patients with lone atrial fibrillation maze lines [8 –15]. Since 1999, we in Berlin have used anrefractory to medical therapy [1– 4]. Our experience with easy method of intraoperative radiofrequency ablationthe Cox-maze operation correlates well with the results performed with a surgical radiofrequency ablation probe.from most centers with a long-term success of 80% to 90% The method can be carried out in a short time and wasin restoring the sinus rhythm [5–7]. However, from a added to elective open heart procedures in patients withsurgical point of view, it is a demanding procedure that organic heart disease and atrial fibrillation. In this studyprolongs significantly the aortic cross-clamp and operat- we report our preliminary experience with this simplifieding time. Therefore, this procedure is not widely ac- maze procedure.cepted. The next logical step is to find a modification ofthe original Cox-maze procedure that will have a similarsuccess rate without the described drawbacks. Patients and Methods Intraoperative radiofrequency ablation is a novel sur- Patientsgical principle for the treatment of atrial fibrillation in Between September 1999 and July 2000, 48 consecutivecombination with a standard open heart operation adults with atrial fibrillation underwent elective open[8 –15]. It is based on the original concept of the maze heart operations (isolated valve procedures or coronaryprocedure developed and introduced by James Cox [1]. artery bypass grafting, n 27 patients; combined proce-Application of radiofrequency current replaces the inci- dures, n 21 patients) (Tables 1 and 2) combined withPresented at the Thirty-seventh Annual Meeting of The Society of intraoperative radiofrequency ablation of the left atrium.Thoracic Surgeons, New Orleans, LA, Jan 29 –31, 2001. There were 28 females and 20 males (age range, 33 to 78Address reprint requests to Dr Pasic, Deutsches Herzzentrum Berlin, years; average age 64 years). The preoperative atrialAugustenburger Platz 1, D-13353 Berlin, Germany; e-mail: fibrillation lasted from 6 months to 36 years with a mean© 2001 by The Society of Thoracic Surgeons 0003-4975/01/$20.00Published by Elsevier Science Inc PII S0003-4975(01)03069-7 Downloaded from by on December 6, 2010
  3. 3. Ann Thorac Surg PASIC ET AL 14852001;72:1484 –91 RADIOFREQUENCY MAZE ABLATIONTable 1. Demographic Data bypass, mild systemic hypothermia of 32°C, and a current cardioplegic technique. Both venae cavae and the posteriorPatient number 48 wall of the left atrium are mobilized. If used, a transesoph-Age (years) 64 10Sex (male/female) 20/28 ageal probe should be removed from the esophagus at thisHeight (cm) 169 9 time. The radiofrequency maze operation is performedWeight (kg) 70 14 prior to the operation for organic heart disease.Body surface area (m2) 1.8 0.2 The radiofrequency maze operation (Berlin modifica- tion) is based on the principle of the left-atrial part of the Cox-maze procedure [1– 4] combined with the method of isolation of the pulmonary veins popularized by Meloof 7 years. Four patients had previous pacemaker implan- and colleagues [9, 10]. (Figs 1 and 2). The Berlin modifi-tations. The mean left ventricular ejection fraction as- cation consists of the standard approach to the left atriumsessed by ventriculography and echocardiography was55%, (range, 27% to 73%) (Table 3). from the right side through the interatrial sulcus (Water- The modified maze procedure was offered to all pa- ston groove) and four standard left atrial maze lines; twotients with atrial fibrillation who were scheduled for maze lines isolate the ostia of the pulmonary veins andelective procedures, to be performed concomitantly with the other two are connecting lines. Instead of the “cutopen heart operations by two of the authors (MP and and sew” technique, the maze lines are performed with aRH). The exclusion criteria for combined modified maze flexible surgical radiofrequency probe and the coagula-procedure and open heart operation were left ventricular tion system (Coagulation ThermaLine System, Bostonfunction less than 25%, extensive and diffuse coronary Scientific, San Jose, CA). The system consists of a cardiacartery disease, acute valve endocarditis, calcification of ablation controller, the electrosurgical probe, connectingthe left atrium, extensive calcification of the mitral valve cables, and a generator of radiofrequency energy. Theannulus requiring annular decalcification, and patients probe (ThermaLine probe, Boston Scientific, San Jose,unwilling to undergo the procedure. CA) (Fig 3) has seven electrodes on the distal part that coagulate the tissue when in contact with the electrodes.Operative Technique During current delivery, the monopolar radiofrequencyThe patient is placed in the standard supine position. The current flows through the tissue toward the indifferenttwo large indifferent patch electrodes are placed on the electrodes. At the location of direct contact between thepatient’s back. The indifferent electrodes and the surgical probe and the atrial endocardium, radiofrequency en-probe are connected to the radiofrequency generator ergy coagulates atrial tissue and creates a deep linearwith the connecting cables. The system is positioned lesion in the atrial wall. The generator settings are 70°Caccording to the space available in the operating room. for temperature and 2 minutes for duration of ablation of The operation is carried out by median sternotomy each line, (ie, the ablation for each line lasts 2 minutes atusing separate caval cannulation, total cardiopulmonary the local temperature of 70°C). The temperature is mea-Table 2. Types of Surgical Procedures Combined With the Simplified Maze Procedure and Intraoperative Data No. of Cross-Clamp PerfusionType of Surgery Patients Time (min) Time (min)All procedures 48 64 17 110 32Mitral valve replacement 16 53 10 88 13Mitral valve repair 5 53 7 86 9Mitral valve replacement and coronary artery bypass grafting 4 65 7 103 6Mitral valve repair and coronary artery bypass grafting 1 82 193Mitral valve replacement and tricuspid valve repair 5 63 7 103 11Mitral valve repair and tricuspid valve repair 1 58 118Aortic valve replacement 3 60 5 106 39Aortic valve replacement and mitral valve replacement 2 92 10 132 1Aortic valve replacement and mitral valve repair 1 66 125Aortic valve replacement and coronary artery bypass grafting 2 80 13 149 40Aortic valve replacement and mitral valve replacement 1 119 197 coronary artery bypass graftingCoronary artery bypass grafting 3 63 12 145 30Ascending aortic replacement and aortic valve repair 1 63 133Mitral valve repair and tricuspid valve repair and atrial septal 1 108 146 defect closureAortic valve replacement and mitral valve replacement and 1 85 147 atrial septal defect closureTricuspid valve repair and atrial reduction 1 69 126 Downloaded from by on December 6, 2010
  4. 4. 1486 PASIC ET AL Ann Thorac Surg RADIOFREQUENCY MAZE ABLATION 2001;72:1484 –91Table 3. Preoperative DataLeft ventricular ejection fraction (%) echo 55 11Left ventricular ejection fraction (%) ventriculography 57 12Left ventricular end-diastolic diameter (mm) 55 8Left ventricular end-diastolic pressure (mm Hg) 14 6Fractional shortening (%) 30 8Right ventricular ejection fraction (%) 56 9Right ventricular end-diastolic diameter (mm) 30 4Left atrial diameter (mm) 47 8Left atrial diameter index (mm/m2)a 26.7 6.0a Left atrial diameter/body surface area.sured by thermocouples integrated into the probe. Thepre-set temperature usually is achieved during the first10 to 15 seconds of ablation. During ablation the opera-tive field should be kept as dry as possible; this can Fig. 2. In the modified method (the Berlin modification), the inci-usually be achieved by using two suckers. Also the lungs sions and sutures of the standard maze technique are replaced byare freed from blood by forced manual ventilation, and radiofrequency ablation lines (dashed lines). The line directions arethen the endotracheal tube is disconnected from the slightly changed. The right and left pulmonary veins are isolatedventilator. Alternatively the pulmonary veins can be separately using two ablation lines instead of one encircling line asseparately encircled with tapes and temporarily snagged. used in the standard maze procedure. The left appendage is notThe contact between the electrode and the endocardium excised.should be good, otherwise the impedance rises andcurrent delivery is shut off. The impedance can also rise quency maze lines are made endocardially from withinif there is blood around the probe. The heat may cause the cavum of the left atrium. The first ablation maze lineformation of small coagula, and in such cases the probe connects both ends of the surgical atriotomy, completingshould be cleaned with wet gauze. isolation of the right pulmonary veins (Fig 4A). The A standard right-sided left atriotomy is made surgi- second ablation maze line isolates the left pulmonarycally parallel to the interatrial groove and then the veins (Fig 4B). This is an encircling line around the orificeradiofrequency maze ablation is performed. All radiofre- of the pulmonary veins. If the veins are enlarged, the encircling line is completed by two applications of the probe. Both lines encircling the pulmonary veins should be placed approximately 10 mm from the venous orifices to prevent possible late stenosis of the pulmonary veins. The third ablation maze line (Fig 4C) connects the encir- cling line of the left pulmonary veins and the middle part of the posterior mitral valve annulus. The line should be placed inferiorly in order to prevent heat damage to the circumflex artery. The last incision (Fig 4D) connects the left-sided and the right-sided encircling lines of the pulmonary veins. It runs along the roof of the atrium in order to prevent possible damage to the esophagus or vagal nerves. The left atrial appendage is left intact, and is neither excised nor oversewn. If chronic thrombotic material is found within the appendage, it should be oversewn in order to prevent possible later embolization. At the end of the procedure, if there are some coagula on the maze lines, they are removed with a wet gauze and then the left atrium is flushed with saline. After finishing the ablation maze procedure, the planned operation for organic heart disease is completed.Fig. 1. The left atrial part of the standard Cox-maze III procedureencompasses excision of the left atrial appendage, multiple incisions Postoperative Antiarrhythmic Medicationwith isolation of the pulmonary veins and consecutive continuoussutures of the left atrial incisions, cryoablation of the dissected coro- The patients were not given any special prophylacticnary sinus and mitral annulus. (The illustration is slightly modified medication postoperatively for the prevention of atrialand reprinted with permission from the American College of Cardi- fibrillation. If a patient remained in sinus rhythm, theology [Journal of the American College of Cardiology 1998;32:1040–7.]) patient did not receive any antiarrhythmic medication. Downloaded from by on December 6, 2010
  5. 5. Ann Thorac Surg PASIC ET AL 14872001;72:1484 –91 RADIOFREQUENCY MAZE ABLATION ative follow-up ranged from 1 to 11 months, with a mean follow-up of 4 months. Statistics and Data Presentation All data are reported as mean standard deviation. After univariate analysis, variables with p less than 0.01 were analyzed by multivariate logistic regression to identify predictors for postoperative atrial fibrillation. A value of p less than 0.05 was considered to be significant. Results There were no perioperative deaths and no reoperations for bleeding. Only 5 patients (10%) needed postoperativeFig. 3. A flexible surgical radiofrequency probe (Thermaline, Boston ventilation longer than 24 hours. The aortic cross-clampScientific, San Jose, CA) can be bent manually to adjust it to the time needed for intraoperative radiofrequency ablationanatomy of the left atrium. The probe has seven coagulation elec- ranged from 6 to 14 minutes with a mean of 11 minutes.trodes at its distal part; six of them are 12.5 mm in length each and The early postoperative recovery was uneventful in allthe tip electrode is only 8 mm long. There is a 2-mm distance be-tween each electrode. Any combination of the electrodes can be se- patients, but two patients died (4% hospital mortality) onlected for ablation. postoperative days 16 and 26 after an initial uneventful course. The causes of death were stroke in 1 patient after mechanical mitral valve replacement with postoperative sinus rhythm, adequate anticoagulation, and no evidenceEarly postoperative patients with junctional rhythm weretreated with continuous intravenous administration oforciprenaline sulfate (Alupent; Boston Scientific, SanJose, CA). Patients with atrial fibrillation during hospital-ization were treated with digoxin in combination withverapamil or digoxin in combination with sotalol or withsotalol or amiodarone alone. After discharge from thehospital, the same regimen of antiarrhythmics was rec-ommended for patients with episodes of postoperativesupraventricular tachyarrhythmias, and we also recom-mended tapering the medication if the rhythm becamestable. If patients did not convert into sinus rhythmunder medical therapy, a direct current shock was rec-ommended. Before cardioversion, transesophageal echo-cardiography was necessary to exclude atrial thrombi.Postoperative Anticoagulant MedicationPostoperatively, anticoagulation medication consists ofheparin and then peroral phenprocoumon (Marcumar;Boston Scientific, San Jose, CA). If a patient did not needlong-term anticoagulation for other reasons (eg, implan-tation of a mechanical valve), we recommended antico-agulation with phenprocoumon for at least 6 months.Thereafter, this medication could be discontinued andreplaced with aspirin in patients with stable sinusrhythm by 24-hour Holter monitoring and normal ornearly normal left atrial contractions determined by Fig. 4. Dashed lines show the position of the radiofrequency mazeechocardiographic examination. lines of the Berlin modification in comparison to the standard surgi- cal maze lines. (A) The first line completes the isolation of the ostiaFollow-up of the right pulmonary veins, (B) and the second maze line isolatedAll patients were followed up by their cardiologists or the ostia of the left pulmonary veins. The pulmonary veins isolation lines are performed about 10 mm away from the ostia of the pulmo-family physicians for adjustment of medication and con- nary veins. (C) The third maze line connects the encircling linetrol of anticoagulation and rhythm. After the operation, around the ostia of the left pulmonary veins (the isolation line of thethe patients were prospectively followed up at 1, 3, and 6 left pulmonary veins) and the middle of the posterior part of themonths. The postoperative rhythm was evaluated with 12 mitral valve annulus. (D) The fourth maze line is a connecting linelead electrocardiogram. However, 24-hour Holter moni- between the two lines that isolate the ostia of the pulmonary veins.toring was not performed on all patients. The postoper- The line lies on the roof of the left atrium. Downloaded from by on December 6, 2010
  6. 6. 1488 PASIC ET AL Ann Thorac Surg RADIOFREQUENCY MAZE ABLATION 2001;72:1484 –91 tified the presence of coronary artery disease as the only variable that determined postoperative recurrence of atrial fibrillation ( p 0.0268; odds ratio 7.5; 80% confi- dence interval, 2.24 –25.13). Comment We describe an easy method of intraoperative radiofre- quency ablation, a simplified left-atrial maze procedure Table 4. P Values of Univariate Analyses for DeterminationFig. 5. Postoperative freedom from atrial fibrillation (% of patients). of Predictors for Postoperative Atrial Fibrillation(OP. operation.) Age (years) 0.4127 Gender (female, male) 0.401of atrial thrombosis using transesophageal echocardiog- Height (cm) 0.1046raphy, and in the other patient late pericardial tampon- Weight (kg) 0.9167ade after coronary bypass revascularization was sus- Body surface area (m2) 0.5324pected. Two patients developed fluid retention with left- Mitral valve disease (yes, no) 1.0sided pleural effusion, which was treated with diuretics. Mitral regurgitation (yes, no) 0.648 All 48 patients left the operating room with sinus Mitral stenosis (yes, no) 0.070rhythm or atrial pacing, but only 12 patients had stable Previous mitral valve surgery (repair, 0.767sinus rhythm during the first postoperative week. The replacement, no)other patients demonstrated electrocardiographic char- Tricuspid valve disease (yes, no) 1.0acteristics of sinus node dysfunction, such as severe sinus Tricuspid incompetence (yes, no) 1.0bradycardia, sinus pause or sinus arrest, sinoatrial exit Aortic valve disease (yes, no) 1.0block, atrial tachyarrhythmias, alternating periods of Aortic regurgitation (yes, no) 0.647atrial bradyarrhythmias and tachyarrhythmias, and atrial Aortic stenosis (yes, no) 1.0fibrillation. Temporary wires were used for temporary Coronary artery disease (yes, no) 0.0327pacing if necessary or to overdrive the atrium. Cardiac Previous myocardial infarction (yes, no) 0.365rhythm was continuously monitored after the operation Previous coronary artery bypass grafting 1.0 (yes, no)until stable rhythm returned. The patients stayed at our Ascending aortic aneurysm (yes, no) 1.0institution for 3 to 7 days until the rhythm stabilized. Atrial septal defect and persistent foramen ovale 1.0Thereafter, patients were transferred back to a referral (yes, no)cardiology department. Five patients (11%) received a Pulmonary hypertension (yes, no) 0.220pacemaker postoperatively because of bradycardia and Mitral valve repair (yes, no) 0.648persistent sinus node dysfunction. The occurrence of Mitral valve replacement (yes, no) 1.0counterclockwise atrial flutter was not recorded in pa- Tricuspid valve repair (yes, no) 0.608tients after their discharge from hospital. At 3 and 6 Aortic valve repair (yes, no) 1.0months postoperatively, all patients without atrial fibril- Aortic valve replacement (yes, no) 0.576lation had a sinus rhythm confirmed by clearly visible P Coronary artery bypass grafting (yes, no) 0.155waves in surface electrocardiogram, and 3 patients with Ascending aortic replacement (yes, no) 1.0pacemaker implantation still had sinus node dysfunction Closure of atrial septal defect or persistent 1.0with pacemaker rhythm. The freedom from atrial fibril- foramen ovale (yes, no)lation was 100% intraoperatively, 25% at 1 week postop- Redo-operation (yes, no) 1.0eratively (12 of 48 patients), 59% at 1 month postopera- Aortic cross-clamp time (min) 0.3171tively (16 of 27 patients), 64% at 3 months postoperatively Cardiopulmonary bypass time (min) 0.0553(16 of 25 patients), and 92% at 6 months postoperatively Operative time (min) 0.0585(12 of 13 patients) (Fig 5). The function of the left atrium Duration of atrial fibrillation (years) 0.3053assessed by transesophageal echocardiography demon- Echocardiography-assessed left ventricular 0.8424strated contractility and atrial transport of different ejection fraction (%)grades of both atria in all patients according to the Left ventricular end-diastolic diameter (mm) 0.3252evidence of Doppler-recorded A waves. Echocardiography-assessed right ventricular 0.2793 Forty preoperative and intraoperative variables were ejection fraction (%)analyzed to determine predictors for postoperative atrial Right ventricular end-diastolic diameter (mm) 0.1200fibrillation. After univariate analysis, only four variables Left atrial diameter (mm) 0.9481had p less than 0.01 (presence of mitral valve stenosis, Left atrial diameter index (mm/m2) 0.8247coronary artery disease, duration of cardiopulmonary Ventriculography-assessed left ventricular 0.7167 ejection fraction (%)bypass time, duration of operation time [Table 4]) and Left ventricular end-diastolic pressure (mm Hg) 0.2842were used for multivariate logistic regression. This iden- Downloaded from by on December 6, 2010
  7. 7. Ann Thorac Surg PASIC ET AL 14892001;72:1484 –91 RADIOFREQUENCY MAZE ABLATIONperformed with a flexible surgical radiofrequency probe. postoperative patients will have normal sinus node func-Our preliminary experience demonstrated results com- tion after radiofrequency maze ablation.parable with those of the standard Cox-maze III proce-dure with a very high percentage of patients with stable Policy Not to Exclude or to Excise Left Atrialsinus rhythm at 6 months postoperatively. The presence Appendageof coronary artery disease decreases the success rate The main difference between both the original Cox-mazeduring the first 6 months postoperatively. The procedure procedure and the isolation of the pulmonary veins andis simple and can be carried out in a short time. It our modification is that the left atrial appendage is lefteliminates the need for multiple incisions in the left intact and is not excised or oversewn. We do not exciseatrium and does not prolong the aortic cross-clamp time the appendage for several reasons. First, it simplifies thesignificantly as does the standard technique. The method surgical procedure significantly, eliminating the need forused is one of several modifications of the intraoperative cutting and oversewing of tissue in this region, which isradiofrequency ablation technique that have been devel- sometimes very fragile and has the circumflex artery inoped recently [8 –15]. the vicinity. Furthermore, in patients with sinus rhythm, We observed a relative high recurrence rate of atrial the left atrial appendage is important for mechanicalfibrillation early postoperatively. We believe that the function of the left atrium. Also, we do not routinelypossible reason is initial inadequate ablation of the atrial exclude the left atrial appendage in other patients withtissue producing incomplete maze lines. It can be postu- atrial fibrillation who do not undergo the maze proce-lated that about 3 to 6 months are needed for complete dure. If chronic thrombotic material is found within thehealing of the lines. Then, after complete scarring of the appendage, it should be oversewn in order to preventmaze lines, they become a total barrier for an electrical possible later embolization. However, in the reportedatrial impulse and eliminate atrial fibrillation. group of patients we saw 2 patients with left atrial thrombi, but the atrial appendage was always free fromSinus Node Dysfunction After Radiofrequency Maze coagula, and therefore the appendage was not oversewn.AblationMechanisms involved in the disturbance of cardiac Possible Complications of the Methodrhythm after the Cox-maze surgical procedure occur as Although we did not observe any complications regard-either primary events of the maze procedure itself or as ing the procedure per se, there are some possible theo-general postoperative complications of open heart oper- retic complications, such as perforation of the left atrialation [5]. The surgically performed bi-atrial Cox-maze III wall and bleeding, or acute or chronic damage of theprocedure includes isolation of the pulmonary veins and neighboring structures and organs (eg, perforation of themultiple incisions in both atria, corresponding to partial esophagus, damage of the n. vagus or coronary arteriesautotransplantation and partial denervation of the heart. and stenosis of the ostia of the pulmonary veins). How-During the follow-up, gradual improvement of sinus ever, these possible complications can be prevented bynode function and atrial contractions was observed with correct placement of the maze lines. The connectingsignificant functional normalization 1 year after the Cox- maze line between the two encircling lines of the left andmaze procedure, corresponding to functional reinnerva- right pulmonary vein should be performed on the roof oftion and recovery of the autonomic nervous system [5, 6]. the left atrium and not in the middle between the veins inOne of the advantages of this simplified approach is that order to stay away from the neighboring organs. Thesinus node function cannot be jeopardized by the place- encircling lines of the ostia of the pulmonary veinsment of the maze lines and it is expected that the should be approximately 10 mm away from the ostia toincidence of postoperative pacemaker implantation prevent possible late stenosis of the pulmonary veins. Toshould be lower than after the Cox-maze surgical proce- prevent possible damage to the circumflex artery, thedure. However, other possible factors that can cause connecting maze line between the encircling line aroundsinus node dysfunction are not eliminated, such as intra- the ostia of the left pulmonary veins (the isolation line ofoperative traction on the heart with retractors and ma- the left pulmonary veins) and the mitral valve annulusnipulation, suture injury, placement of caval cannulas, should be directed to the middle of the posterior part ofinadequate atrial preservation during cardiopulmonary the mitral valve annulus. Furthermore, the echocardio-bypass, hemorrhage, ischemia, necrosis, disturbance of graphic probe should be removed from the esophagusautonomic neural control, humoral and electrolyte dis- during the procedure to exclude possible interference withbalance, and the effect of cardiovascular drugs, such as radiofrequency energy and possible esophageal injury.sympatholytic agents or antiarrhythmics [5]. Further-more, the patients can already have sinus node dysfunc- Limitations of the Studytion before the operation because of atrial fibrosis that We reported our preliminary experience with this sim-follows chronic atrial fibrillation. Latent concomitant dys- plified method and therefore, our study has severalfunction can be masked by atrial fibrillation, being rec- limitations. These limitations comprise a small number ofognized only postoperatively after sinus rhythm is estab- patients without a control group, rhythm evaluationlished. This could not have been excluded only by using only 12 lead electrocardiogram without 24-hourpreoperative electrocardiographic findings or anamnes- electrocardiogram in all patients, and short follow-ups.tic data [5]. Therefore, it should not be expected that all This study can only be considered an observational study Downloaded from by on December 6, 2010
  8. 8. 1490 PASIC ET AL Ann Thorac Surg RADIOFREQUENCY MAZE ABLATION 2001;72:1484 –91because of its limitations, and a prospective randomized and chronic fixed atrial fibrillation. J Am Coll Cardiol 1998;study should be the next step. However, we were able to 32:1040–7. 6. Pasic M, Musci M, Siniawski H, Grauhan O, et al. Thedemonstrate that the method is easy to perform, and Cox-maze procedure: parallel normalization of sinus nodeyields a very good 6-month rhythm control result. dysfunction, improvement of atrial function, and recovery of In conclusion, the modified maze procedure using the cardiac autonomic nervous system. J Thorac Cardiovascintraoperative radiofrequency maze ablation of the left Surg 1999;118:287–96.atrium combined with an operation for organic heart 7. Pasic M, Musci M, Edelmann B, Siniawski H, Bergs P, Hetzer R. Identification of p waves after the Cox-maze procedure:disease effectively eliminates atrial fibrillation without significance of right precordial leads V3R through V6R. Annsignificant prolongation of the aortic cross-clamp and Thorac Surg 1999;67:1292– 4.operative time. Because of the excellent results of this 8. Chen M-C, Guo B-F, Chang J-P, Yeh K-H, Fu M. Radiofre-study, we have changed our standard surgical policy by quency and cryoablation of atrial fibrillation in patients undergoing valvular operations. Ann Thorac Surg 1998;65:adding this modified, short-lasting left atrial maze pro- 1666–72.cedure to elective open heart procedures in all patients 9. Melo J, Adragao PR, Neves J, et al. Electrosurgical treatmentwith atrial fibrillation. However, the long-term results of atrial fibrillation with a new intraoperaive radiofrequencyand comparisons to other ablation systems (ie, micro- ablation catheter. Thorac Cardiovasc Surg 1999;47(Suppl):wave, cryo, and laser) are needed. 370–2. 10. Melo J, Adragao PR, Neves J, et al. Surgery for atrial fibrillation using radiofrequency catheter ablation: assess-We thank Anne Gale for editorial assistance, Helge Haselbach ment of results at one year. Eur J Cardiothorac Surg 1999;15:and Annette Gaussmann for the illustrations, and Julia Stein for 851– 4.statistical analyses. 11. Benussi S, Pappone C, Nascimbene S, et al. A simple way to treat chronic atrial fibrillation during mitral valve surgery: the epicardial radiofrequency approach. Eur J CardiothoracReferences Surg 2000;17:524–9. 12. Melo J, Adragao P, Neves J, et al. Endocardial and epicardial 1. Cox JL, Schuessler RB, D’Agostino HJ Jr, et al. The surgical radiofrequency ablation in the treatment of atrial fibrillation treatment of atrial fibrillation. III. Development of a defini- with a new intraoperative device. Eur J Cardiothorac Surg tive surgical procedure. J Thorac Cardiovasc Surg 1991;101: 2000;18:182– 6. 569– 83. 13. Patwardhan AM, Dave HH, Tamhane AA, et al. Intraopera- 2. Cox JL, Boineau JP, Schuessler RB, Jaquiss RDB, Lappas DG. tive radiofrequency microbipolar coagulation to replace in- Modification of the maze procedure for atrial flutter and cisions of maze III procedure for correcting atrial fibrillation atrial fibrillation. I. Rationale and surgical results. J Thorac in patients with rheumatic valvular disease. Eur J Cadiotho- Cardiovasc Surg 1995;110:473– 84. rac Surg 1997;12:627–33. 3. Cox JL. The surgical treatment of atrial fibrillation. IV. 14. Mottkamp H, Hindricks G, Hammel D, et al. Intraoperative Surgical technique. J Thorac Cardiovasc Surg 1991;101: radiofrequency ablation of chronic atrial fibrillation: a left 584–92. atrial curative approach by elimination of anatomic “an- 4. Cox JL, Jaquiss RDB, Schuessler RB, Boineau JP. Modifica- chor” reentrant circuits. J Cardiovasc Electrophysiol 1999;10: tion of the maze procedure for atrial flutter and atrial 772– 80. fibrillation. II. Surgical technique of the maze III procedure. 15. Sie HT, Beukema WP, Ramdat Misier AR, Elvan A, Ennema J Thorac Cardiovasc Surg 1995;110:485–95. JJ, Wellens HJ. The radiofrequency modified maze proce- 5. Pasic M, Musci M, Siniawski H, Edelmann B, Tedoriya T, dure. A less invasive surgical approach to atrial fibrillation Hetzer R. Transient sinus node dysfunction after the Cox- during open-heart surgery. Eur J Cardiothorac Surg 2001;19: maze III procedure in patients with organic heart disease 443–7.DISCUSSIONDR MICHAEL ARGENZIANO (New York, NY): I would like to ber of patients, demonstrated comparable success rates at 6begin by thanking the program committee for inviting me to months, as shown in this slide, but found no relationshipdiscuss this paper and by congratulating Dr Pasic and his between left atrial size and the rate of successful ablation. Whatcolleagues for an excellent presentation and for sending me a is your definition of giant left atrium, and do you think that thesecopy of their manuscript in advance. patients are untreatable with this method? In this paper, Dr Pasic and colleagues report their experience Second, your method of radiofrequency ablation is differentwith a modified left atrial radiofrequency ablation procedure from that used by our group and others, as you have noted, inperformed concomitant with coronary bypass or valvular sur- that you isolate the pulmonary veins and then add only a lesiongery, or both. Despite the lack of randomization and absence of from the left pulmonary vein isolation line to the mitral annulus.control groups, the authors are to be congratulated on this As we have reported, we make a single encircling lesion aroundimpressive clinical series, which demonstrates the feasibility, the pulmonary veins and a lesion to the mitral annulus, but alsosafety and efficacy of surgical endocardial radiofrequency abla- isolate the left atrial appendage and add a connecting line fromtion of atrial fibrillation. the pulmonary vein isolation line to the appendage isolation I have several comments and questions for the authors. Other line. We add these appendage lesions in order to excludegroups have reported inferior success rates for radiofrequency arrhythmogenic foci within the left atrial appendage and toisolation in patients with left atria larger than 6 or 7 cm, and you prevent arrhythmias based on reentrant conduction around thestate in your paper that you excluded patients with “giant left base of the appendage. Did you skip the appendage isolationatrium,” but provide no definition of this entity. Our group at and connecting lines because you consider them unnecessary orColumbia, which recently reported its results in a similar num- merely to save time? Also, with respect to your technique of Downloaded from by on December 6, 2010
  9. 9. Ann Thorac Surg PASIC ET AL 14912001;72:1484 –91 RADIOFREQUENCY MAZE ABLATIONseparate isolation of left and right pulmonary veins, which At our institution, giant left atrium was considered a contra-actually takes longer than isolation of all four veins with a single indication for the surgically performed Cox-maze III procedure.encircling lesion, do you think that the small intervening strip of However, the radiofrequency maze procedure is an easy methodposterior left atrium that is thus spared makes any real contri- that can be carried out in a short time and, at present, we do notbution to left atrial contractile function? consider giant left atrium as a contraindication for radiofre- This slide depicts a specimen taken from one of our early quency maze ablation. We are aware that it is possible to obtainpatients who underwent combined mitral repair and radiofre- good results in these patients regarding electrical function of thequency ablation of the left atrium. This patient had a normal left atrium and conversion into sinus rhythm, but the postoper-preoperative and intraoperative transesophageal echocardio- ative mechanical function of the left atrium is not good becausegram, revealing no thrombus in the left atrium or appendage. of extensive histological changes in the wall of the dilatedWe can see here that the left atrial appendage is in fact filled atrium.with thrombus. Because of concern about the potential for Your second question was about our policy not to exclude orbleeding, we now routinely exclude the appendage mechani- excise the left atrial appendage on a routine basis. We do notcally by ligating the orifice from within the atrium with a purse routinely exclude the left atrial appendage in patients with atrialstring suture rather than by resecting it as we did here. Regard- fibrillation who do not undergo the maze procedure. Therefore,ing your patient who died of a stroke postoperatively, what was we also do not do so in patients undergoing radiofrequencythe rhythm before death, and do you think it is possible that the maze ablation. There are several reasons not to excise thesource of the embolus could have been from the left atrial appendage. First, it simplifies the surgical procedure signifi-appendage? cantly, eliminating the need for cutting and oversewing of tissue Finally, you stated that you did not perform right atrial in this region, which is sometimes very fragile and has theablation because surface mapping studies have indicated that circumflex artery in the vicinity. Furthermore, in patients withatrial fibrillation is usually associated with left-sided arrhythmo- sinus rhythm the contribution of left atrial appendage is impor-genic foci. Although this may be the case, it has also been shown tant for mechanical function of the left atrium. We wouldthat patients with atrial fibrillation are predisposed to atrial exclude the atrial appendage if chronic thrombotic material isflutter as well, which in fact is often initiated by right atrial foci. found within the appendage. In this case it should be oversewnIn our series, 8 of 42 patients had right-sided as well as left-sided in order to prevent possible later embolization. However, in thelesions created. None of these patients had postoperative atrial reported group of patients we have seen two patients with leftflutter, while 7 of 34 patients receiving only left-sided lesions atrial thrombi, but the atrial appendage was always free fromhad at least one episode of atrial flutter. Two of these patients, in coagula and therefore, the appendage was not oversewn.fact, on medium term follow-up are in persistent atrial flutter. It Your further comment was about our technique of separateis therefore our current practice to add right-sided lesions in isolation of the pulmonary veins using two separate isolationpatients with a history of atrial flutter or those who are under- lines, one for the left and one for the right veins, instead of onegoing concomitant right-sided procedures. Did any of your encircling line as in the classic maze procedure. There are twopatients, all of whom received only left-sided lesions, have atrial reasons why we do this: (1) the simplicity of the technicalflutter postoperatively? procedure, because we use a long and flexible radiofrequency I would like to close by again congratulating the authors on a probe that enables us to perform one isolation line in 2 minuteswell-conducted and elegantly presented study that I believe is by a single application of the probe, and (2) we believe that thean important contribution to the expanding body of literature in posterior wall should not be excluded from the mechanicalthis exciting new field of surgical interest, and by thanking the activity of the left atrium. Using our technique, the posteriorSociety for the privilege of the floor. atrial wall is not electrically isolated and it may contribute to mechanical atrial function but, if the standard maze technique isDR PASIC: Thank you very much, Dr Argenziano, for your applied, this part of the atrial wall is excluded from the mechan-comments and your questions. They are important issues re- ical activity of the left atrium.garding surgery for atrial fibrillation and the maze procedure. One patient died of stroke after mechanical valve replace- I would like to emphasize that there is no clear definition of ment. At the time, the patient had sinus rhythm and was under“giant left atrium.” This definition is mostly established accord- adequate anticoagulation. Furthermore, there was no evidenceing to the echocardiographically measured diameter of the left of atrial thrombosis using transesophageal echocardiography.atrium. However, I believe that an echocardiograhically mea- We can not rule out that the source of the embolus could havesured diameter, although mostly used, is a confusing parameter been from the left atrial appendage or from the maze lines, butand probably should not be used for the definition. The volume also it was not possible to exclude other sources of embolization,of the left atrium is the better parameter for the definition of such as from the ascending aorta or aortic arch or carotid artery.giant left atrium. An enlarged left atrium has three diameters Our policy to perform only the left atrial maze procedure isand usually we receive only one measured by echocardiography. based on our goal to perform an easy and short procedure. TheThere are three distances that should be measured: (1) between bi-atrial procedure would certainly increase the success rate ofthe right and left pulmonary veins, (2) between the mitral valve elimination of atrial fibrillation, but it would also prolong theand the roof of the atrium, and (3) the height of the left atrium. operating time in patients who do not need a right atrialTherefore, I suggest that all three distances should be measured procedure. Except in some patients in the early postoperativein order to assess the volume of the atrium. A volume of 250 mL course, the occurrence of atrial flutter was not recorded inpresents a giant left atrium. patients after discharge from hospital. Thank you. Downloaded from by on December 6, 2010
  10. 10. Intraoperative radiofrequency maze ablation for atrial fibrillation: the Berlin modificationMiralem Pasic, Peter Bergs, Peter Müller, Michael Hofmann, Onnen Grauhan, Hermann Kuppe and Roland Hetzer Ann Thorac Surg 2001;72:1484-1491Updated Information including high-resolution figures, can be found at:& Services This article cites 14 articles, 13 of which you can access for free at: This article has been cited by 32 HighWire-hosted articles: Collections This article, along with others on similar topics, appears in the following collection(s): Electrophysiology - arrhythmias hmiasPermissions & Licensing Requests about reproducing this article in parts (figures, tables) or in its entirety should be submitted to: or email: For information about ordering reprints, please email: Downloaded from by on December 6, 2010