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Ann Thorac Surg 2002;74:1506-1509
© 2002 The Society of Thoracic Surgeons

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Original article: cardiovascular

Epicardial radiofrequency ablation of both atria in the treatment of atrial fibrillation: experience in patients

^a Department of Cardiac Surgery, Austin and Repatriation Medical Centre, University of Melbourne, Melbourne, Victoria, Australia

* Address correspondence to Dr Raman, Department of Cardiac Surgery, Austin and Repatriation Medical Centre, Studley Rd, Heidelberg, Melbourne, Victoria 3084, Australia.
e-mail: jai.raman{at}armc.org.au

Presented at the Poster Session of the Thirty-eighth Annual Meeting of The Society of Thoracic Surgeons, Fort Lauderdale, FL, Jan 28–30, 2002.

	Abstract

Top Abstract Introduction Patients and methods Results Comment References

 
BACKGROUND: Despite success with the Maze procedure and its modifications in treating atrial fibrillation, longer procedure times and increased morbidity have precluded widespread use. The operative treatment for atrial fibrillation associated with aortic valve disease and ischemic heart diseases have not been established. We report the early results of epicardial radiofrequency coagulation on both atria and discuss the availability of this procedure.

METHODS: The Australasian database of radiofrequency ablation lists 130 patients with established or frequent intermittent atrial fibrillation that underwent various cardiac surgical procedures between March 2000 and March 2002. Forty patients without mitral valve disease underwent epicardial radiofrequency coagulation on both atria. Twenty-eight patients were in established chronic atrial fibrillation, 9 in paroxysmal atrial fibrillation, and 3 patients had atrial flutter. The primary surgical procedures were coronary artery bypass grafting in 19 patients, aortic valve replacement in 9, coronary artery bypass grafting plus aortic valve replacement in 8, and other procedures in 4 patients.

RESULTS: The procedure increased the cross-clamp time by a mean of 10 minutes. Three patients required defibrillation postoperatively, within the first 3 months and have since stayed in sinus rhythm. One patient had late atrial flutter that was cardioverted to sinus rhythm. Sinus recovery rate was 93.7% (15 of 16 patients) at 6 months and 100% in 8 patients reviewed at 12 months. Atrial contractility was maintained.

CONCLUSIONS: Epicardial radiofrequency coagulation may be a very effective way of converting patients with atrial fibrillation into sinus rhythm.

	Introduction

Top Abstract Introduction Patients and methods Results Comment References

 
The operative treatments for atrial fibrillation (AF) associated with aortic valve disease and ischemic heart diseases have not been established. Despite successful results in treating AF with the maze procedure [1] and its modifications [2], these procedures are not suitable for patients without mitral valve disease due to the attendant increase in operative time and morbidity. In contrast, radiofrequency coagulation (RFC) is relatively quick to perform and creates lesions in the myocardium through resistive heating, thereby creating scars that cause electrical block. We evaluated an RFC catheter that was malleable and had seven electrodes (Cobra, EPT; Boston Scientific, San Jose, CA) initially in animals. As we have mentioned in our previous report [3], we first applied RFC endocardially in the left atrium as part of mitral valve procedures along with epicardial application on the right atrium. Histopathology of the test epicardial lesions revealed full-thickness alteration of atrial tissue in 10 of 12 patients (83%) [3]. Although the thermal injury was not transmural on histopathology in 2 of the patients, the deepest part of the atrial tissue appeared abnormal and there was macroscopic evidence of blanching of the endocardial surface of the atrium. We had performed animal experiments that showed efficacy of epicardial lesions as long as the probe was heated to 85°C (unpublished data). Thereafter, as we grew more confident of the transmural nature of the epicardial lesions, we proceeded to perform more epicardial lesions in patients undergoing aortic valve replacement and coronary artery bypass grafting. In this article we focus on the early results of epicardial RFC of both atria in patients without mitral valve disease and discuss the availability of this procedure.

	Patients and methods

Top Abstract Introduction Patients and methods Results Comment References

 
One hundred thirty patients underwent radiofrequency coagulation as an adjunct to a variety of cardiac surgical procedures between March 2000 and March 2002 at 17 hospitals across Australia and New Zealand. Among them, 40 patients without mitral valve disease were treated using the epicardial RFC procedure at 10 hospitals. The mean age of these 22 patients was 69.8 ± 7.9 years, ranging from 51 to 86 years. Patients included 34 men and 6 women. The mean left atrial diameter was 4.5 ± 0.3 cm preoperatively. Twenty-eight patients were in chronic established AF, 9 had paroxysmal AF, and 3 patients had atrial flutter at the time of their operation. All of these patients had preoperative Holter monitoring to document their abnormal rhythm. Mean duration of rhythm disturbance was 105 months, ranging from 2 months to 20 years. Paroxysmal or frequent episodic AF was defined as more than three episodes a week. The breakdown of the primary surgical procedures was as follows: 19 patients underwent coronary artery bypass grafting; 9 had aortic valve replacement; 8 patients underwent coronary artery bypass grafting in conjunction with aortic valve replacement; and the other 4 had miscellaneous other procedures. All surviving patients were followed up for more than 3 months after operation with a clinical examination, echocardiogram, and a Holter monitor. To promote maintenance of early postoperative sinus rhythm, all patients were commenced on low-dose amiodarone (200 mg/day) for 6 months after operation.

We chose to use a combination of radiofrequency lesions based on the bilateral isolation of pulmonary veins proposed by Melo and colleagues [4] and the radial procedure proposed by Nitta and colleagues [5]. We adapted the salient features of this lesion set for a predominantly epicardial approach for patients undergoing aortic valve replacement and coronary artery bypass grafting without left atrial opening. All lesions were created using radiofrequency energy delivered by a malleable RFC catheter with seven electrodes at a minimum temperature of 85°C for a period of 2 minutes. The left atrial lesions were created on an arrested heart on cardiopulmonary bypass initially. As confidence grew, these lesions were created on a heart, decompressed adequately by cardiopulmonary bypass. The sequence of lesions is shown in Figure 1. The left atrial appendage was opened and evacuated. The appendage was closed at its base using a pursestring suture. Linear lesions were created along the roof of the left atrium extending down to the interatrial septal area, after dissecting the interatrial groove. Left- and right-sided pulmonary veins were then isolated. The right-sided lesions were created epicardially on the surface of the right atrium with the heart beating and ejecting on cardiopulmonary bypass. A single lesion was created roughly along the crista terminalis from the superior vena cava to the inferior vena cava. A connecting lesion was then created from the lower end of this lesion on to the atrioventricular groove low down opposite the orifice of the coronary sinus to create a block in the cavotricuspid isthmus area (Fig 2). Extensive dissection of the tissue at the right atrioventricular groove was not carried out. The increase in aortic occlusion time for RFC averaged 10 minutes. All values are expressed as mean ± standard deviation.

View larger version (94K): [in this window] [in a new window]   Fig 1. Epicardial radiofrequency lesions on the left atrium. The numbers indicate the sequence of the steps of the procedure: step 1, lesion along the roof of the left atrium; step 2, ligation of the base of the left atrial appendage; step 3, encircling lesion around the left-sided pulmonary veins; step 4, encircling lesion around the right-sided pulmonary veins; and step 5, lesion going toward the atrioventricular groove but stopped by the coronary sinus.

View larger version (99K): [in this window] [in a new window]   Fig 2. Epicardial lesions on the right atrium. Step 6: lesion along the body of the right atrium, roughly along the crista terminalis. The sinoatrial (SA) node is variable in location and attempts are made to stay well away from it. Step 7: aims to connect that lesion to the atrioventricular groove opposite the orifice of the coronary sinus.

	Results

Top Abstract Introduction Patients and methods Results Comment References

Follow-up results were available in 8 patients at 12 months, 16 patients at 6 months, and 25 patients at 3 months. Three patients required defibrillation at 8, 14, and 88 days postoperatively. These 3 patients have since stayed in sinus rhythm. One patient had an episode of asymptomatic atrial flutter 15 months postoperatively. He was defibrillated successfully. This patient had presented with chronic AF initially and was asymptomatic postoperatively. He was able to run up small hills with no symptoms. He presented for a review at 15 months with mild tachycardia and flutter diagnosed on electrocardiography.

All 8 patients reviewed at 12 months were in a regular sinus rhythm. Fifteen of 16 patients (93.75%) reviewed at 6 months were in sinus rhythm. Twenty-two of 25 patients (88%) reviewed at 3 months were in sinus rhythm. One patient required permanent pacemaker implantation 6 months postoperatively for sinus bradycardia. Postoperative echocardiogram at a mean of 3 months after operation showed reasonable left atrial contraction in sinus rhythm; early diastolic filling velocity (E-wave) was 1.0 ± 0.4 m/s and peak atrial filling velocity (A-wave) was 0.4 ± 0.1 m/s.

Five patients have had transesophageal echocardiographic studies that showed widely patent pulmonary veins and normal pulmonary vein orifices.

	Comment

Top Abstract Introduction Patients and methods Results Comment References

 
In the field of catheter treatment, radiofrequency energy has been already used and selective ablation of ectopic electrical foci has been effective in the treatment of focal AF [6] and other supraventricular tachycardias [7]. Use of intraoperative radiofrequency treatment has recently started; however, the majority of these techniques have been endocardial in conjunction with mitral valve procedures and modified maze procedures [8, 9]. The application of radiofrequency energy to create scars appears reasonably effective in patients with mitral valve disease with a success rate of 81% to 91% [8–10]. However, the treatment strategies for AF in patients without mitral valve disease have not been clearly established. In these patients epicardial application of radiofrequency energy might be more favorable than the endocardial approach because of reduced operative time and avoidance of left atrial incisions. Benussi and colleagues [11] recently showed that similar results could be achieved by creating epicardial lesions around the pulmonary veins during mitral valve surgery. Melo and associates [12] have also shown epicardial lesions in off-pump procedures to be reasonably effective. There is still controversy about whether epicardial application creates full-thickness lesions capable of causing persistent electrical block. Our histopathologic results of test epicardial coagulation of atrial tissue revealed the capability of consistently creating transmural lesions [3]. Our animal evaluation of the Cobra probe showed that endocardial lesions performed on bloodless atrial tissue required a temperature setting of at least 80°C for 2 minutes (unpublished data).

Furthermore, to get full transmural lesions on a decompressed atrium that is beating, the temperature setting for each lesion is at least 85°C for 2 minutes. The issue of postoperative flutter is complex and so is epicardial radiofrequency treatment of flutter. Cox and Ad [13] suggest that cryoablation near the coronary sinus during the Maze procedure prevents flutter. Our limited epicardial RFC on both atria close to the left and right atrioventricular groove are attempts to prevent postoperative flutter. Longer follow-up of these patients will indicate if this approach is effective.

We have chosen to use the term RFC rather than ablation because ablation conjures up images of a local explosion. Surgical use of radiofrequency energy in the atria is similar to the use of a branding iron to create scars. The scars are created by coagulative necrosis caused by radiofrequency energy, which then act as line of electrical block.

In this study, the follow-up results were encouraging in patients with aortic valve disease and coronary artery disease who underwent nonmitral procedures along with RFC. Melo and associates [12] have also shown 6 of 7 patients without mitral disease were out of AF after epicardial radiofrequency treatment. The preoperative left atrial diameter in patients with aortic valve or coronary artery disease is usually smaller than that in patients with mitral valve disease. Actually the mean atrial diameter of our patients was 4.5 ± 0.3 cm preoperatively. Patients with large atria have a higher recurrence rate of AF after surgical radiofrequency ablation [12]. Hence, patients without mitral valve disease may be the better candidates for this treatment. Doppler echocardiography is usually used to evaluate the atrial contraction and transportation function by measuring transmitral flows. Hauw and colleagues [8] have mentioned that right atrial contractility was seen in 89% and left atrial transport in 91% after radiofrequency-modified Maze procedure. Quantification of atrial function is sometimes difficult because diastolic function of the ventricle is influenced by the patients’ age, underlying heart disease [14], and operative procedure. Moreover, the presence of a mitral valve prosthesis or a repair alters transmitral velocities significantly, muddying the analyses.

In our study postoperative echocardiography showed reasonable left atrial contraction in sinus rhythm. Thomas and colleagues [15] mention that multiple linear radiofrequency lesions in the atria may impair atrial contractility in the animal model. We did not see any evidence of this assertion in our animal studies. We believe the advantages of recovery to sinus rhythm after RFC treatment are enough to overcome short-term problems with atrial contraction that may be a consequence of atrial stunning.

Questions about short- and long-term safety have been raised many times, as have risks of pulmonary vein stenosis with radiofrequency ablation. Prospectively collected data on patients in the Australasian registry since March 2000 have not shown a single case of atrial, esophageal, or any soft tissue perforation. In patients undergoing epicardial RFC, the probe is pressed onto the epicardial surface of the atria under vision and is unlikely to be pushed against other soft tissue structures. The postoperative transesophageal echocardiographic studies have not shown any evidence of pulmonary vein stenosis. This is also because surgical RFC is performed under direct vision and care is taken to stay well away from the pulmonary vein orifices.

Epicardial RFC as a procedure is new and in a developmental stage. Further refinements of the equipment, technique, lesion set, and temperature settings are being worked on to ensure transmurality even in very thick atrial tissue.

	References

Top Abstract Introduction Patients and methods Results Comment References

 

1. Cox J.L. The surgical treatment of atrial fibrillation. IV. Surgical technique. J Thorac Cardiovasc Surg 1991;101:584-592.[Abstract]
2. Cox J.L., Jaquiss R.D., Schuessler R.B., Boineau J.P. Modification of maze procedure for atrial flutter and atrial fibrillation. II. Surgical technique of the maze III procedure. J Thorac Cardiovasc Surg 1995;110:485-495.[Abstract/Free Full Text]
3. Raman J.S., Seevanayagam S., Storer M., Power J.M. Combined endocardial and epicardial radiofrequency ablation of right and left atria in treatment of atrial fibrillation. Ann Thorac Surg 2001;72:S1096-S1099.[Abstract/Free Full Text]
4. Melo J.Q., Adragao P., Neves J., et al. Surgery for atrial fibrillation using radiofrequency catheter ablation: assessment of results at one year. Eur J Cardiothorac Surg 1999;15:851-855.[Abstract/Free Full Text]
5. Nitta T., Lee R., Schuessler R.B., Boineau J.P., Cox J.L. Radial approach: a new concept in surgical treatment for atrial fibrillation. I. Concept, anatomic and physiologic bases and development of a procedure. Ann Thorac Surg 1999;67:27-35.[Abstract/Free Full Text]
6. Haissaguerre M., Jais P., Shah D.C., et al. Right and left atrial radiofrequency catheter therapy of paroxysmal atrial fibrillation. J Cardiovasc Electrophysiol 1996;7:1132-1144.[Medline]
7. Jackman W.M., Beckman K.J., McClelland J.H., et al. Treatment of supraventricular tachycardia due to atrioventricular nodal reentry, by radiofrequency catheter ablation of slow-pathway conduction. N Engl J Med 1992;327:313-318.[Abstract]
8. Hauw T.S., Beukema W.P., Misier A.R.A., Elvan A., Ennema J.J., Wellens H.J.J. The radiofrequency modified maze procedure. A less invasive surgical approach to atrial fibrillation during open-heart surgery. Eur J Cardiothorac Surg 2001;19:433-447.
9. Pasic M., Bergs P., Muller P., et al. Intraoperative radiofrequency maze ablation for atrial fibrillation: the Berlin modification. Ann Thorac Surg 2001;72:1484-1490.[Abstract/Free Full Text]
10. Williams M.R., Stewart J.R., Bolling S.F., et al. Surgical treatment of atrial fibrillation using radiofrequency energy. Ann Thorac Surg 2001;71:1939-1944.[Abstract/Free Full Text]
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 Cardiothorac Surg 2000;17:524-529.[Abstract/Free Full Text]
12. Melo J.Q., Adragao P., Neves J., et al. Endocardial and epicardial radiofrequency in the treatment of atrial fibrillation with a new intra-operative device. Eur J Cardiothorac Surg 2000;18:182-186.[Abstract/Free Full Text]
13. Cox J.L., Ad N. The importance of cryoablation of the coronary sinus during the maze procedure. Sem J Thorac Cardiovasc Surg 2000;12:20-24.
14. Otto C.M. Textbook of clinical echocardiolography, 2nd ed. Philadelphia: WB Saunders, 2000:132-152.
15. Thomas S.P., Med B., Nicholson I.A., et al. Effect of atrial radiofrequency ablation designed to cure atrial fibrillation on atrial mechanical function. J Cardiovasc Electrophysiol 2000;11:77-82.[Medline]

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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Jai S. Raman Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Raman, J. S. Articles by Power, J. M. Search for Related Content PubMed PubMed Citation Articles by Raman, J. S. Articles by Power, J. M. Related Collections Electrophysiology - arrhythmias