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Ann Thorac Surg 1995;60:361-363
© 1995 The Society of Thoracic Surgeons

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Original Articles: Cardiovascular

Cox Maze Operation Without Cryoablation for the Treatment of Chronic Atrial Fibrillation

Department of Surgery, State University of Londrina Medical School, Londrina, Paraná, Brazil

Accepted for publication March 17, 1995.

	Abstract

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 
Background. From August 1993 to May 1994, 20 patients (mean age, 43 years) with atrial fibrillation underwent the maze operation without cryoablation. Ten patients had mitral stenosis, 5 had mitral insufficiency, and 5 had a mixed mitral lesion. The mean left atrial diameter as measured on echocardiograms was 6.1 cm. The cause was rheumatic in 17 patients (85%) and degenerative in 3 (15%). Seven patients had had previous episodes of thromboembolism.

Methods. Mitral valvuloplasty was performed on 7 patients, mitral commissurotomy on 4, and mitral valve replacement on 9. Thrombi were found in the left atrium of 7 patients and also in the right atrium in 2. The mean cross-clamp time was 73 minutes (range, 52 to 108 minutes).

Results. Patients were discharged from the hospital in good condition. Hemodynamic studies and Doppler echocardiograms showed significant reduction in the left atrial diameter (mean diameter, 4.9 cm; p < 0.01) in 18 patients. The two-channel Holter monitor showed sinus rhythm in 15 patients, atrial ectopic rhythm in 4, and atrial fibrillation in 1. Eleven patients (55%) experienced atrial fibrillation (9 in the first 3 months postoperatively), which was reversed with quinidine. Ninety percent of patients had development of an effective, synchronous, atrial systole. Six to 15 months postoperatively (average follow-up, 10 months), all patients were in functional class I, and 18 were not on a regimen of antiarrhythmic medication.

Conclusions. This simplification of the maze operation has been demonstrated to be an effective alternative for the treatment of chronic atrial fibrillation.

	Introduction

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 
See also page 364.

In 1991, Cox and associates [1–4] described a new procedure for the surgical treatment of atrial fibrillation, the maze operation, and presented their clinical experience. In 1993, McCarthy and colleagues [5] at the Cleveland Clinic confirmed the excellent results obtainable with this new technique. In Brazil, Jatene and co-workers [6] reported successful results using this operation in association with the surgical treatment of mitral valve disease.

As 40% of all surgical procedures on our service are related to valvular disease, most involving atrial fibrillation, we were encouraged by these favorable reports to adopt this technique. In August 1993, the first patient underwent the maze operation without cryoablation on our service. This surgical procedure was used because of the lack of proper equipment for cryoablation. Here we discuss our initial experience with the maze operation without cryoablation in 20 patients with mitral valve disease and chronic atrial fibrillation.

See also page 354.

	Material and Methods

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 
The maze operation was carried out on 20 patients (14 female and 6 male) from August 1993 to May 1994. This group comprises all patients with chronic atrial fibrillation associated with mitral valve disease who had surgical treatment during this period. The mean age was 43 years (range, 16 to 72 years). All patients were seen with chronic atrial fibrillation (duration of more than 1 year) and had tried several regimens of antiarrhythmic therapy without success. Six patients had also undergone electric cardioversion.

All patients had mitral valve disease: mitral stenosis in 10, mitral insufficiency in 5, and a mixed mitral valve lesion in 5 (Table 1). The cause was rheumatic in 85% of patients and degenerative in only 15%. Associated tricuspid insufficiency was found in 5 patients, tricuspid stenosis in 1, and coronary insufficiency with stable angina in 1. All patients were in New York Heart Association class III or IV.

A longitudinal median sternotomy with hypothermic (25°C) extracorporeal circulation and distal cannulation of the venae cavae was performed on all patients. After the clamping of the aorta, crystalloid cardioplegic solution at 4°C (St. Thomas') was infused. The infusion was repeated at 20-minute intervals. The left and right atrial appendages were excised. The incision in the right atrium was extended toward the inferior vena cava and then interrupted at the midpoint of the atrium. The same incision was carried toward the dome of the left atrium. The atrial septum was incised to the inferior border of the fossa ovalis. Wide exposure of the mitral valve was obtained with these openings, thus allowing adequate manipulation.

Mitral valvuloplasty was performed on 7 patients using a Gregori-Braile [7] ring in 6 and a Wooler annuloplasty in 1. Mitral commissurotomy and isolated papillotomy were performed on 4 patients and mitral valve replacement with a bioprosthesis, on 9. Thrombi were removed from the left atrium of 7 patients and also from the right atrium in 2. One female patient also underwent myocardial revascularization.

After the mitral valve procedure, the left atrium was incised, starting from the classic point above the venae cavae and extending circularly so as to isolate the pulmonary veins in the left atrium. The mitral valve ring was incised perpendicularly into the endocardium, starting at the midpoint of the posterior annulus, leaving intact the myocardial fibers, and wide dissection of the coronary sinus was carried out. Such wide dissection was needed, as no cryoablation was employed. The left atrium was closed with continuous 3-0 polypropylene sutures. Starting below the superior vena cava, an incision was made parallel to the interatrial sulcus and crossing the right atrium. Another incision, originating from the previous one and also crossing the right atrium, extended toward the tricuspid valve. The ring of the tricuspid valve was dissected at the site of the posterior leaflet implantation, thus eliminating all the myocardial fibers next to the insertion of the posterior leaflet in the tricuspid ring. A De Vega tricuspid valvuloplasty was performed on 5 patients and a tricuspid commissurotomy on 1. Finally, the superior vena cava was opened longitudinally in its anterior face, the incision extending approximately 2 cm toward the right atrium.

The mean extracorporeal circulation time was 108 minutes (range, 73 to 142 minutes). The mean myocardial ischemic time was 73 minutes (range, 52 to 108 minutes).

Before they were discharged from the hospital, the patients underwent cardiac catheterization (A wave), echocardiography (left atrial diameter), and two-channel Holter monitoring. The postoperative follow-up ranged from 6 to 15 months (average follow-up, 10 months). Patients had echocardiography and two-channel Holter monitoring during this time.

	Results

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 
After the release of the aortic clamp, the heart rate returned to 60 to 100 beats per minute in all patients. Eight were in sinus rhythm and 12, junctional rhythm. In the immediate postoperative period, the rhythm was junctional in 10 patients. In the majority of patients, cardiac rhythm had to be continuously maintained with dopamine hydrochloride. We considered a pacemaker but chose dopamine because of the advantages of maintaining the heart rate and a synchronous atrial-ventricular contraction. The patients showed alternating rhythms (sinus and junctional) until the 20th postoperative day when all established a regular rhythm.

In 14 patients, fluid retention was successfully treated with diuretics. Intrahepatic cholestasis developed in 1 patient, who recovered in 8 days. This patient also had pericardial and pleural effusions, which were surgically drained.

The patients were discharged from the hospital at a mean time of 12 days (range, 8 to 27 days) in good condition and without antiarrhythmic drugs. The Doppler echocardiograms and hemodynamic studies showed atrial contraction in 18 patients (90%) (see Table 1). The average left atrial diameter by echocardiography was 4.9 cm (minimum diameter, 3.2 cm; maximum diameter, 6.4 cm) (p < 0.01 versus preoperative value). Nine patients had development of atrial fibrillation in the first 3 months postoperatively but returned to sinus rhythm with quinidine. Two patients experienced atrial fibrillation in the fifth postoperative month, and 1 returned to sinus rhythm. The 24-hour electrocardiographic evaluation (Holter monitor) showed sinus rhythm in 15 patients, atrial ectopic rhythm in 4, and atrial fibrillation in 1. An effective, synchronous atrial systole was observed in 18 patients (90%).

	Comment

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 
Atrial fibrillation is commonly associated with mitral valve disease, and its treatment is complicated. It rarely responds to medical or even electric cardioversion, especially when the mitral valve disease is untreated. A high percentage of patients, particularly those with a dilated or hypertrophic left atrium, continue to have atrial fibrillation in the postoperative period. Thromboembolic complications or use of antiarrhythmic and anticoagulation drugs can have drastic consequences. Atrial fibrillation often represents a risk to the success of the surgical treatment of the mitral valve.

We agree with Chua and co-workers [8] that atrial fibrillation after mitral valvuloplasty does not cause serious complications. Our experience with more than 700 cases of conservative surgical treatment of mitral valve disease (300 mitral valvuloplasties and 400 commissurotomies) shows that thromboembolic events are more common in patients who have atrial fibrillation after mitral commissurotomy. However, the most frequent complications in patients with atrial fibrillation postoperatively are due to the difficulty of controlling the anticoagulation regimen. This problem arises because of the low socioeconomic status of our patients.

Cox and associates [9] presented late postoperative results for 75 patients who underwent the maze operation. Ninety-five percent were in sinus rhythm, 89% of them without the use of antiarrhythmic medication. The surgical procedure was developed initially to obtain more effective results when using antiarrhythmic drugs late postoperatively. The authors did not expect the atrial fibrillation to simply disappear.

All the patients in our study group had mitral valve lesions. Cryoablation was not used; instead, the atrial tissue that encircles the posterior ring of the mitral valve and the tricuspid valve was widely incised. Despite the fact that the initial reason for choosing this procedure was the lack of cryoablation equipment, we were convinced that the same results could be obtained using wide dissection instead of cryoablation as initially described by Cox [4].

Atrial fibrillation developed postoperatively in 11 (55%) of our patients (in the first 3 months in 9) and was reversed in all but 1 patient. In the study by McCarthy and associates [5], atrial fibrillation developed in 6 (43%) of 14 patients during the first 14 days after operation, and in the patients of Cox and associates [9], it occurred in 47%. Our patients returned to sinus rhythm after the introduction of antiarrhythmic drugs. The rhythm was maintained late postoperatively, even after discontinuation of the drugs.

All patients are currently asymptomatic, with significant reduction in left atrial size demonstrated by the postoperative echocardiograms. The maze operation restored a regular rhythm, and an effective atrial systole was present in 90% of patients. We conclude that the maze operation without cryoablation seems to be an effective surgical treatment of chronic atrial fibrillation associated with mitral valve disease.

	Footnotes

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 
Address reprint requests to Dr Gregori, Rua Paes Leme, 1264, 7o. andar, sala 701, Londrina, Paraná, Brazil CEP 86010-520.

	References

Top Footnotes Abstract Introduction Material and Methods Results Comment References

 

1. Cox JL, Schuessler RB, Boineau JP. The surgical treatment of atrial fibrillation. I. Summary of current concepts of the mechanisms of atrial flutter and atrial fibrillation. J Thorac Cardiovasc Surg 1991;101:402–5.[Abstract]
2. Cox JL, Canavan TE, Schuessler RB, et al. The surgical treatment of atrial fibrillation. II. Intraoperative electrophysiologic basis of flutter and atrial fibrillation. J Thorac Cardiovasc Surg 1991;101:406–26.[Abstract]
3. Cox JL, Schuessler RB, D'Agostino HJ, et al. The surgical treatment of atrial fibrillation. III. Development of a definitive surgical procedure. J Thorac Cardiovasc Surg 1991;101: 569–83.[Abstract]
4. Cox JL. The surgical treatment of atrial fibrillation. IV. Surgical technique. J Thorac Cardiovasc Surg 1991;101:584–92.[Abstract]
5. McCarthy PM, Castle LW, Maloney JD, et al. Initial experience with the maze procedure for atrial fibrillation. J Thorac Cardiovasc Surg 1993;105:1077–81.[Abstract]
6. Jatene AD, Sosa E, Tarasoutch F, et al. Tratamento cirúrgico da fibrilaçao arterial. Procedimento do ``labirinto''. A experiência inicial. Rev Bras Cir Cardiovasc 1992;7:107–11.
7. Gregori F Jr, Silva SS, Hayashi S, et al. Mitral valvuloplasty with a new prosthetic ring. Analysis of the first 105 cases. Eur J Cardio-thorac Surg 1994;8:168–72.[Abstract]
8. Chua YL, Schaff HV, Orzulak TA, Morris JJ. Outcome of mitral valve repair in patients with preoperative atrial fibrillation. Should the maze procedure be combined with mitral valvuloplasty? J Thorac Cardiovasc Surg 1994;107:408–15.[Abstract/Free Full Text]
9. Cox JL, Boineau JP, Schuessler RB, Kater KM, Lappas DG. Five-year experience with the maze procedure for atrial fibrillation. Ann Thorac Surg 1993;56:814–24.[Abstract]

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This Article Abstract 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): Francisco Gregori, Jr Wilson J. Couto Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Gregori, F. Articles by Nechar, A. Search for Related Content PubMed PubMed Citation Articles by Gregori, F., Jr Articles by Nechar, A., Jr Related Collections Related Articles