Ann Thorac Surg 2003;75:51-56
© 2003 The Society of Thoracic Surgeons
Original article: cardiovascular
The effect of maze operations on atrial volume
Emile R. Jessurun, MDa,
Norbert M. van Hemel, MDa*,
Johannes C. Kelder, MDa,
Jo A.M.T. Defauw, MDa,
Aart Brutel de la Rivière, MDa,
Jef M.P.G. Ernst, MDa,
Wybren Jaarsma, MDa
a Departments of Cardiology and Cardiothoracic Surgery, St. Antonius Hospital, Nieuwegein, The Netherlands
Accepted for publication July 26, 2002.
* Address reprint requests to Dr van Hemel, MD, Department of Cardiology, St. Antonius Hospital, Koekoekslaan 1, 3435 CM Nieuwegein, The Netherlands.
e-mail: rdcardio{at}worldonline.nl
 |
Abstract
|
|---|
BACKGROUND: Unmodified maze III operations show long-term eradication of atrial fibrillation (AF) in more than 85% of patients with or without structural heart disease. The effect of this procedure on atrial volumes is not known.
METHODS: Two patient populations were studied: (1) patients undergoing unmodified maze III operations combined with surgical structural heart disease, mostly mitral valve operations (group A; n = 32); and (2) patients with only AF selected for unmodified maze III operations (group B; n = 32). In groups A and B, transthoracic Doppler echocardiographic studies were prospectively made preoperatively, and at 3 and 12 months postoperatively. Left and right atrial dimensions and volumes and atrial contractions were determined and compared with base line patient characteristics and 12 months arrhythmia outcomes.
RESULTS: One year postoperatively all patients were alive. In groups A and B, 92% were free of AF and other atrial arrhythmias. A significant reduction of left atrial volume at 1 year postoperatively was apparent in group A, whereas the left atrial volume did not change significantly in group B. The reduction observed in group A was not related to postoperative age, type or duration of AF, or late atrial arrhythmia outcome. In both groups the right atrial volume remained unchanged at 12 months postoperatively.
CONCLUSIONS: The unmodified maze III operation does not affect atrial volume in patients without structural heart disease. In patients with structural heart disease, the mitral valve operation contributes to the reduction of left atrial volume and dimension by improving the hemodynamic condition.
|
Introduction
|
|---|
The unmodified maze III operation offers successful long-term eradication of atrial fibrillation (AF) with preservation of the sinus node function [1–10]. Repeated echocardiographic studies of operated patients showed a maintained atrial contraction in the majority of patients [7–11]. However, left and right atrial volume postoperatively have not been prospectively examined [5–8]. Because the maze operation is often carried out in conjunction with another cardiac operation, both interventions can independently determine the postoperative changes of atrial volumes. To define the course of these changes, we studied the atrial volumes of patients operated on for drug-refractory AF with and without an additional cardiac operation. The results have contributed to our understanding of ablative and surgical treatment of AF.
|
Patients and methods
|
|---|
Patient selection
Group A patients were less than 80 years of age with paroxysmal or chronic AF who underwent a maze operation in conjunction with an operation for mitral valve disease, atrial septal defect closure, and revascularization of less than two-vessel diseased coronary arteries. Group B patients underwent only a maze operation because of absence of structural heart disease; these patients had only AF.
Echocardiography
To examine left ventricular dimension and function, two-dimensional transthoracic Doppler echocardiographic studies were performed with a 2.5 MHz transducer (Sonos 5500; Hewlett-Packard Company, Andover, MA). The left ventricular ejection fraction was calculated with the Teichholz formula [12]. The atrial volumes were calculated with the formula described by Hiraishi and colleagues [13]. Mitral and tricuspid valve competence and diastolic inflow measurements (E/A ratio), indicating the relationship between early (E) and late (A) transmitral inflow, were assessed. Presence of A wave representing atrial contraction was defined as peak A wave velocity of more than 20 cm/s [14]. Because the E/A ratio is a multifactorial finding, only A waves were reported.
Maze operation
An unmodified maze III operation was carried out in all patients [1, 2]. Additional cardiac operations included repair or replacement of mitral valve or tricuspid valve, atrial septal closure, and standard coronary revascularization. In all patients anticoagulant therapy with sodium warfarin was administered beginning the first postoperative day. In group B patients the anticoagulants were replaced by aspirin 3 months after maze operation.
Follow-up studies
Patients were questioned specifically to determine symptomatic arrhythmias and cerebrovascular accidents. Electrocardiographic measurements, Holter recordings, bicycle stress testing, and transthoracic Doppler echocardiographic studies were carried out 3 and 12 months postoperatively.
Statistical analysis
Variables are reported as mean ± standard deviation or percentages. Student’s t test, Mann–Whitney U test, Fischer’s exact test, and repeated measures of analysis of variance were used for comparison. Multivariate linear regression analysis was used to assess the association of base line variables with atrial dimension and volumes. A p less than 0.05 was considered statistically significant.
|
Results
|
|---|
Patients
From 1993 to 1999, 97 consecutive patients underwent maze operations without in-hospital mortality. The preoperative, 3-month and 12-month postoperative echocardiographic studies made in our institution were available for 32 patients in group A and 32 patients in group B (total, 66%); in the remainder of patients the data were incomplete. The preoperative demographic and clinical profiles and surgical procedures of 64 patients are listed in Table 1.
Of patients in group A, 14 were diagnosed with a rheumatic etiology and 16 with a degenerative etiology.
Surgical results
Rhythm
One year postoperatively, sinus rhythm without AF was present in 30 of 32 (94%) patients in group A, whereas AF persisted despite antiarrhythmic drugs and repeat direct current cardioversion in 2 patients. One patient without AF needed chronic pacing for sick sinus syndrome emerging more than 6 months postoperatively. In 31 of 32 (97%) patients in group B, sinus rhythm without AF was observed. One patient had intractable paroxysmal AF, and 2 patients had very symptomatic paroxysmal ectopic atrial tachycardias, requiring His bundle ablation and pacing. One patient without AF received chronic cardiac pacing for sick sinus syndrome occurring 12 months postoperatively.
Valvular operation
In group A, 2 patients had mitral valve regurgitation caused by failure of the valvuloplasty, requiring reoperation and implantation of a prosthetic valve 12 months postoperatively. In the remaining patients no valvular incompetence was detected.
Stroke
In group A, 1 patient with a mechanical prosthetic valve had a cerebral hemorrhage within 1 year postoperatively. In group B no thromboembolic complications were observed.
Echocardiographic results
Atrial contribution to ventricular filling
In groups A and B the frequency of a normal right A wave showed a clear increase at 1 year postoperatively, although this development was already visible at 3 months postoperatively (Table 2).
The number of patients with a normal left A wave in group A increased from 34% to 53% and remained unchanged in about 60% of the patients in group B.
Atrial volume changes
Preoperative measurements
Multivariate analysis of the preoperative base line characteristics, age, gender, and duration of AF showed that only age predicted both left atrial dimension and right atrial volume (p = 0.0017 and p = 0.0035, respectively); older patients had larger volumes and dimensions. Left atrial volume was not associated with any of the base line characteristics.
Postoperative measurements
A significant reduction in left atrial diameter and volume was found in patients in group A (Table 3,
Fig 1).
A significant reduction of left atrial diameter and volume was also observed in group B at 3 months postoperatively; however these measurements did not differ clearly from the preoperative values at 12 months postoperatively (Table 3, Fig 2).
In group A the right atrial volume became significantly smaller postoperatively, but after 12 months this reduction was not maintained (Table 3, Fig 3).
In group B the right atrial volume was reduced at 3 months postoperatively, but after 1 year the right atrial volume was not significantly smaller (Table 3, Fig 3).
View larger version (18K):
[in this window]
[in a new window]
|
Fig 1. The relationship between the preoperative (x-axis) and 12-month postoperative (y-axis) left atrial (LA) volume of patients with (group A) and without (group B) structural heart disease with linear regression lines. The regression in group A is postoperative = 0.55 x preoperative volume (p= 0.001); the regression in group B is postoperative = 0.89 x preoperative volume (p= 0.001). Left atrial volume of group A patients (circles) was clearly larger than group B patients (diamonds). A reduction of the volume was specifically seen in group A patients.
|
|
View larger version (20K):
[in this window]
[in a new window]
|
Fig 2. The relationship between the preoperative (x-axis) and 12-month postoperative (y-axis) left atrial (LA) dimension of patients with (group A) and without (group B) structural heart disease with linear regression lines. The regression in group A is postoperative = 0.83 x preoperative volume (p = 0.001); the regression in group B is postoperative = 0.97 x preoperative volume (p = 0.001). Left atrial dimension of group A patients (circles) was clearly larger than group B patients (diamonds). A significant reduction of the diameter was seen only in group A.
|
|
View larger version (20K):
[in this window]
[in a new window]
|
Fig 3. The relationship between the preoperative (x-axis) and 12-month postoperative (y-axis) right atrial (RA) dimension of patients with (group A) and without (group B) structural heart disease with linear regression lines. The regression in group A is postoperative = 0.76 x preoperative volume (p = 0.0001); the regression in group B is postoperative = 0.77 x preoperative volume (p = 0.001). Right atrial dimension of group A patients (circles) was clearly larger than group B patients (diamonds). A significant reduction of the volume was seen only in group A.
|
|
No difference in the reduction of left atrial dimensions and left and right atrial volumes could be found between patients who underwent mitral valve plasty or prosthetic valve implantation. Because only 2 patients had persistent AF and 2 had paroxysmal ectopic atrial tachycardias, the number of patients with postoperative AF was too small to determine any relationship between changes of atrial dimension, atrial volume, and surgical arrhythmia failure. Furthermore, comparison of left and right atrial transport preoperatively and postoperatively, and changes in left and right atrial volumes, did not show any statistically significant correlation.
Left ventricular function
In groups A and B left ventricular ejection fraction 1 year postoperatively remained unchanged compared with the preoperative values (Table 3). One may assume that the stage of mitral valve disease would differ between group A patients with paroxysmal or chronic AF; however, no difference in the changes of the mean left ventricular ejection fraction was observed (chronic AF -4.7%; paroxysmal AF +3.6%; p = 0.05).
|
Comment
|
|---|
Key findings and causes
This study demonstrates that the arrhythmia outcome of maze operations was excellent, as 92% of the patients were free from AF and other atrial arrhythmias, without in-hospital and 1-year mortality or serious morbidity. Left atrial diameter and volumes determined at 12 months postoperatively became significantly smaller in patients operated on for structural heart disease combined with maze operations in group A. However, in group B left atrial diameter and volumes of patients with maze operations for AF without structural heart disease had not changed significantly at 1 year postoperatively. Finally, the right atrial volume did not become smaller in either group.
These findings strongly suggest that the incisions and cryoablations of maze operations only transiently reduce the left and right atrial volume. The complete wound healing process of the various incisions takes 2 to 3 months, which can be the reason for these results. However, 12 months postoperatively for lone AF (group B), the atrial volumes regained their preoperative values, suggesting that the scarring process of maze operations further limit the expansion of the atria after the initially smaller size documented in the first postoperative months. The initial reduction is explained by the tissue needed and thus taken from the atrial wall for appropriate apposition and closure of the incisions. The preserved reduction of left atrial volume in patients with combined operations (group A) can be ascribed to the improved hemodynamics after successful mitral valve operations and not maze operations. Despite the fact that echocardiography in half of the patients in group A and one third of those in group B did not show atrial contraction, the atrial volumes remained comparable with the preoperative values. This observation suggests that atrial contraction does not always determine the postoperative atrial volume and diameter.
Atrial volume and contraction
Although a higher frequency of atrial contractions after maze operations is sometimes reported [7–11, 15], this finding should be interpreted with caution. Preoperative atrial standstill during paroxysmal or chronic AF at the time of the echocardiographic examination; lack of atrial transport as a transient effect of spontaneous, electrically or drug-induced cardioversion; and the presence of a prosthetic valve postoperatively are three important factors limiting the interpretation of follow-up examinations of atrial contraction. Using magnetic resonance imaging and transesophageal echocardiography, Cox and colleagues [1, 2] reported on right and left atrial contraction in 98% and 93% of patients, respectively, after maze operation. Our findings based on transthoracic echocardiography are concordant with reports using similar methods showing right and left atrial contraction in 80% to 90% and 60% to 70% of patients, respectively, 1 year after maze operation [7–11, 15]. Despite that half the patients in group A and one third in group B did not show atrial contraction, the atrial volumes remained comparable with the preoperative values. This observation suggests that atrial contraction is not always a determinant for postoperative atrial volume.
Atrial volume and atrial fibrillation
Because no obvious reduction of atrial volumes was observed in patients exclusively operated on for maze operations, the eradication of AF should be attributed to the incisions and cryoablations of this procedure. Recent investigations suggest that atrial size reduction can inhibit the emergence of AF reentrant wavelets and dominant rotors in AF [16–18]. Some studies report that the success of maze operations is dependent on atrial size reduction [7, 9, 10]. Our results seem to disprove this concept, and this divergent opinion can be attributed to two factors. The evolution of radiofrequency linear lesions differs from surgical incisions in size and extension [19, 20] and second, additional mitral valve operations also determine postoperative atrial volume and size. Prospective studies are needed to evaluate the significance of our findings for anticoagulation therapy in the prevention of thromboembolic complications after maze operations.
Study limitations
In group B paroxysmal AF was the dominant arrhythmia (Table 1). It cannot be excluded that maze operations in chronic AF without structural heart disease can give rise to different results. Atrial contraction and contribution to ventricular filling was studied with transthoracic echocardiography. This approach can induce false results, specifically in patients with prosthetic valves. Episodes of postoperative asymptomatic AF may have been missed because electrocardiographic measurements and Holter recordings were routinely made during visits to the outpatient clinic or when arrhythmia symptoms arose. Postoperative antiarrhythmic drug treatment and direct current cardioversion were determined by the cardiologist, which may have affected arrhythmia outcome.
Conclusion
Unmodified maze III operations do not affect left and right atrial volume as measured more than 1 postoperative year. When a mitral valve operation is combined with a maze operation, the left atrial volume reduction should be attributed to the hemodynamic improvement of the mitral valve operation.
|
References
|
|---|
- Cox J.L., Boineau J.P., Schuessler R.B., Kater K.M., Lappas D.G. Five-year experience with the maze procedure for atrial fibrillation. Ann Thorac Surg 1993;56:814-824.[Abstract]
- Cox J.L., Niv A., Palazo T., et al. The maze-III procedure combined with valve surgery. Semin Thorac Cardiovasc Surg 2000;12:53-55.[Medline]
- Fukada J., Morishita K., Komatsu K., et al. Is atrial fibrillation resulting from rheumatic mitral valve disease a proper indication for the maze procedure?. Ann Thorac Surg 1998;65:1566-1570.[Abstract/Free Full Text]
- Kobayashi J., Kosakai Y., Nakano K., Sasako Y., Eishi K., Yamamoto F. Improved success rate of the maze procedure in mitral valve disease by new criteria for patients’ selection. Eur J Cardiothoracic Surg 1998;13:247-252.[Abstract/Free Full Text]
- Kamata J., Kawazoe K., Izumoto H., et al. Predictors of sinus rhythm restoration after Cox maze procedure concomitant with other cardiac operations. Ann Thorac Surg 1997;64:394-398.[Abstract/Free Full Text]
- Chua Y.l, Schaff H.V., Orszulak T.A., Morris J.J. Outcome of mitral valve repair in patients with preoperative atrial fibrillation; should the maze procedure be combined with mitral valvuloplasty?. J Thorac Cardiovascular Surg 1994;107:408-415.[Abstract/Free Full Text]
- Yuda S., Nakatani S., Isobe F., Kosakai Y., Miyatake K. Comparative efficacy of the maze procedure for restoration of atrial contraction in patients with and without giant left atrium associated with mitral valve disease. J Am Coll Cardiol 1998;31:1097-1102.[Abstract/Free Full Text]
- Jessurun E.R., van Hemel N.M., Defauw J.A., et al. Results of maze surgery for lone paroxysmal atrial fibrillation. Circulation 2000;101:1559-1567.[Abstract/Free Full Text]
- Yashima N., Nasu M., Kawazoe K., Hiramori K. Serial evaluation of atrial function by Doppler echocardiography after the maze procedure for chronic atrial fibrillation. Eur Heart J 1997;18:496-502.[Abstract/Free Full Text]
- Kim Y.J., Sohn D.W., Park D.G., et al. Restoration of atrial mechanical function after maze operation in patients with structural heart disease. Am Heart J 1998;136:1070-1074.[Medline]
- Feinberg M.S., Waggoner A.D., Kater K.M., et al. Restoration of atrial function after the maze procedure for patients with atrial fibrillation. Assessment by Doppler echocardiography. Circulation 1994;90(Part 2):II-285-292.
- Teichholz L.E., Kreulen T., Herman M.V., Gorlin R. Problems in echocardiographic volume determinations: echocardiographic-angiographic correlations in the presence or absence of asynergy. Am J Cardiol 1976;37:7-11.[Medline]
- Hiraishi S., DiSessa T.G., Jarmakani J.M., Nakanishi T., Isabel-Jones J., Friedman W.F. Two-dimensional echocardiographic assessment of left atrial size in children. Am J Cardiol 1983;52:1249-1257.[Medline]
- Gardin J.M., Dabestani A., Takenaka K., et al. Doppler transmitral flow velocity parameters: relationship between age, body surface area, blood pressure and gender in normal subjects. Am J Noninvas Cardiol 1987;1:3-10.
- Chen M.-C., Chang J.-P., Guo B.-F., Chang H.-W. Atrial size reduction as a predictor for the success of radiofrequency maze procedure for chronic atrial fibrillation in patients undergoing concomitant valvular surgery. J Cardiovasc Electrophysiol 2001;12:867-874.[Medline]
- Mandapati R., Skanes A., Chen J., Berenfeld O., Jalife J. Stable microreentrant sources as a mechanism of atrial fibrillation in the isolated sheep heart. Circulation 2000;101:194-199.[Abstract/Free Full Text]
- Ravelli F., Allessie M. Effects of atrial dilatation on refractory period and vulnerability to atrial fibrillation in the isolated Langendorff-perfused rabbit heart. Circulation 1997;96:1686-1695.[Abstract/Free Full Text]
- Sanfillippo A.J., Abascal V.M., Sheehan M., et al. Atrial enlargement as a consequence of atrial fibrillation. Circulation 1990;82:792-797.[Abstract/Free Full Text]
- Avitall B., Urbonas A., Urboniene D., Millard S., Helms R. Time course of left atrial mechanical recovery after linear lesions: normal sinus rhythm versus a chronic atrial fibrillation dog model. J Cardiovasc Electrophysiol 2000;11:1397-1406.[Medline]
- Haines D.E. In atrial fibrillation, size does matter. J Cardiovasc Electrophysiol 2000;11:1407-1408.[Medline]
Top
Abstract
Introduction
