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Ann Thorac Surg 1999;68:805-810
© 1999 The Society of Thoracic Surgeons

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Original Articles: Cardiovascular

Initial experience with the radial incision approach for atrial fibrillation

^a Department of Cardiothoracic Surgery, Nippon Medical School, Tokyo, Japan

Address reprint requests to Dr Nitta, Cardiothoracic Surgery, Nippon Medical School, 1-1-5, Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan
e-mail: nitta_takashi/surg2{at}nms.ac.jp

Presented at the Thirty-fifth Annual Meeting of The Society of Thoracic Surgeons, San Antonio, TX, Jan 25–27, 1999.

	Abstract

Top Abstract Introduction Patients and methods Results Comment References

 
Background. Surgery for atrial fibrillation (AF) is performed with the aim of restoring sinus rhythm and atrial transport function, and preventing thromboembolism. The radial incision approach (RIA), in which the atrial incisions radiate from the sinus node toward the atrioventricular annular margins and parallel the coronary arteries, was developed as an outgrowth of and an alternative to the maze procedure in order to preserve a more physiological activation sequence and the atrial transport function.

Methods. To determine whether the RIA is a promising procedure for AF, 23 patients who had undergone the RIA (n = 10) or the maze procedure (n = 13) for chronic AF associated with valvular heart disease were examined in terms of the postoperative cardiac rhythm and atrial transport function.

Results. AF was cured in 90% of RIA patients and 92.3% of maze patients (not significant). One patient in each group required pacemaker implantation for an insufficient sinus rate postoperatively. The RIA was technically easier than the maze procedure, because the incisions were more linear and there was no isolation incision or "T-shape" incision in the left atrium. The left atrial transport function, assessed by transthoracic Doppler echocardiography, was greater after the RIA than after the maze procedure, while the right atrial transport function was equally preserved by both procedures. The peak atrial filling/early filling waves of the flow-velocity spectra across the mitral valve was significantly larger after the RIA than after the maze procedure (0.58 ± 0.17 vs. 0.25 ± 0.07, p < 0.005). The left atrial filling fraction was significantly larger after the RIA than after the maze procedure (28.5% ± 5.0% vs. 15.1% ± 4.0%, p < 0.001).

Conclusions. RIA provides a greater atrial transport function, and thus may represent a physiological alternative to the maze procedure as a surgical procedure for AF.

	Introduction

Top Abstract Introduction Patients and methods Results Comment References

 
The purpose of surgery for atrial fibrillation (AF) includes restoration of sinus rhythm and atrial contraction sufficient to maintain the physiologic hemodynamics and to prevent formation of intraatrial thrombi. The maze procedure cures AF and restores sinus rhythm and some degree of atrial mechanical function in a majority of patients with or without organic heart disease [1, 2]. However, insufficient left atrial transport function is occasionally seen in patients after the procedure [2, 3]. Thus, the procedure does not necessarily achieve all of the above purposes. The possible mechanisms underlying the insufficient left atrial transport function after the maze procedure are the isolated posterior left atrium between the pulmonary vein orifices, discordant activation of neighboring atrial segments across the incisions, delayed activation at the lateral left atrium, and the interrupted atrial coronary arteries. The radial incision approach (RIA), in which the atrial incisions radiate from the sinus node toward the atrioventricular annular margins and parallel the coronary arteries, was developed as an outgrowth of an alternative to the maze procedure in order to preserve a more physiological activation sequence and the atrial transport function [4]. One of the authors has previously shown, in normal canines, that the RIA preserves a more physiological activation sequence and a greater atrial transport function than the maze procedure [5].

The objective of this study was to determine if the RIA is a promising procedure for AF. Specifically, patients who underwent the RIA or maze procedure for AF associated with valvular heart disease were examined in terms of the postoperative cardiac rhythm and atrial transport function.

	Patients and methods

Top Abstract Introduction Patients and methods Results Comment References

 
Patient population
From October 1997 to July 1998, 11 patients with chronic AF associated with valvular heart disease underwent the RIA concomitantly with valve surgery. One 67-year-old man, who underwent aortic and mitral valve replacement and the RIA, died in the early postoperative period of ischemic-reperfusion injury of the lower extremity. This patient was excluded from the study, and the remaining 10 patients were examined (RIA group). The data were compared with the data of 13 patients who underwent the maze procedure from November 1993 to June 1995 (Maze group). The preoperative characteristics of the patients are compared between the groups in Table 1. These characteristics did not differ significantly between the groups. All patients had heart failure with a New York Heart Association (NYHA) functional class grade of 2 or 3 before surgery. Although the AF had lasted for more than 2 years in all patients by the time of surgery, the accurate duration of the AF was not determined in all of the patients because of inadequate medical records or an unclear patient memory. The preoperative cardiothoracic ratio (CTR) and left atrial dimension (LAD), determined by echocardiography, did not differ significantly between the groups.

View larger version (29K): [in this window] [in a new window]   Fig 1. Schematic of the atrial incisions and cryolesions in the RIA. The upper, middle, and lower panels represent the superior and posterior epicardium and the interatrial septum, respectively. The small dark region of the right atrium at the junction with the SVC represents the sinus node, and the arrows indicate the activation sequence after the procedure. The broken lines indicate the atrial incisions, and the shaded region represents the excised left atrial appendage. The small shaded circles indicate the cryolesions at the atrioventricular valve annuli. All the pulmonary vein orifices are cryoablated circumferentially (shaded). The asterisks in the middle and lower panels are the epicardial and endocardial aspects of the identical sites. (MV = mitral valve; TV = tricuspid valve; RAA = right atrial appendage; LAA = left atrial appendage; SVC = superior vena cava; IVC = inferior vena cava; FO = fossa ovalis; CS = coronary sinus.)

The mitral deceleration time of the E wave was also measured from the transmitral Doppler flow spectra. Each measurement was obtained as an average of five cardiac cycles.

Statistical analysis
All the continuous variables were expressed as mean ± 1 SD. The data were compared between the groups by analysis of variance. Noncontinuous variables, such as the NYHA functional class, were compared by the ² test. A value of p less than 0.05 was considered statistically significant. The study protocol was approved by the research committee of the institute, and informed consent for surgery was obtained from each patient.

	Results

Top Abstract Introduction Patients and methods Results Comment References

 
Operative procedures
The aortic cross-clamp time was 174.2 ± 36.8 minutes in the RIA and 165.0 ± 48.1 minutes in the maze procedure. Although the difference between the procedures was not significant, the RIA was technically easier than the maze procedure. The number of cryoablations in the left atrium was nine or more in the RIA versus three in the maze procedure. Two patients after the maze procedure required reexploration of the chest for postoperative bleeding, whereas no patients had this complication after the RIA. Exposure of the mitral valve in the RIA was sufficient to perform mitral valve surgery, just as in the maze procedure. No additional atrial incision was required to expose the mitral valve. The entire annulus and leaflets of the mitral valve were visible and accessible in all patients. The postoperative follow-up period was 46.0 ± 12.0 months after the maze procedure and 11.1 ± 4.1 months after the RIA. One patient after the maze procedure died of sepsis due to inappropriate antibiotic treatment after dental treatment 10 months postoperatively. In the remaining patients, there were no morbidities, such as heart failure or thromboembolic complications.

Postoperative cardiac rhythm
There was 1 patient in each group who was not cured of AF postoperatively. Thus, the cure rate for AF was 90% after the RIA and 92.3% after the maze procedure. The difference in the cure rate between the procedures was not statistically significant. Among the patients, in which sinus rhythm resumed, there was no recurrence of AF during a follow up period of 49.0 ± 5.1 months after the maze procedure and 10.7 ± 4.2 months after the RIA.

The patients in both groups who were not cured of AF had a larger left atrium (Fig 2). In the patients who resumed sinus rhythm after the RIA, the LAD was 51 ± 9 mm, whereas it was 70 mm in the patient with AF postoperatively. The LAD was 52 ± 6 mm in the patients who resumed sinus rhythm after the maze procedure, and 67 mm in the patient with AF postoperatively.

View larger version (13K): [in this window] [in a new window]   Fig 2. The preoperative left atrial dimension in relation to the postoperative cardiac rhythm after the RIA and the maze procedure. Open circles denote the patients with sinus rhythm, and the closed circles denote those with AF after the surgery.

Atrial transport function
The A wave of the transmitral and transtricuspid flow was detected in all the patients. The left atrial transport function was greater after the RIA than after the maze procedure (Fig 3). The peak A/E was 0.58 ± 0.17 after the RIA and 0.25 ± 0.07 after the maze procedure. The peak A/E was significantly larger after the RIA than after the maze procedure (p < 0.005). The AFF was 28.5% ± 5.0% after the RIA and 15.1% ± 4.0% after the maze procedure. The AFF was significantly larger after the RIA than after the maze procedure (p < 0.001). There was no significant difference in the right atrial transport function between the procedures (Fig 4). The peak A/E was 0.70 ± 0.19 after the RIA and 0.66 ± 0.17 after the maze procedure. The AFF was 43.4% ± 8.4% after the RIA and 33.1% ± 7.4% after the maze procedure. The mitral deceleration time was 218 ± 49 ms after the RIA and 213 ± 47 ms after the maze procedure. The difference was not significant between the procedures.

View larger version (36K): [in this window] [in a new window]   Fig 3. The left atrial transport function after the RIA and maze procedure. Both the peak A/E and AFF were significantly larger after the RIA than after the maze procedure.

View larger version (34K): [in this window] [in a new window]   Fig 4. The right atrial transport function after the RIA and maze procedure. There was no significant difference between the procedures in both the peak A/E and AFF.

	Comment

Top Abstract Introduction Patients and methods Results Comment References

Because the study was not performed in a prospective fashion, the duration from the time of surgery to the time when the atrial transport function was evaluated differed between the groups. A potential serial change in the atrial transport function after the procedures was not considered in the present study. The atrial transport function after the RIA is unlikely to decrease in the long-term period after the surgery, because the atrial transport function has been shown to improve gradually in patients after the maze procedure [14]. Development of adhesions around the atrial incisions may restrict the mechanical motion of the atria in the long-term postoperative period. In fact, the atrial reservoir function has been shown to decrease after the maze procedure and RIA in the canine study [5]. The patients should be carefully followed for years to find the serial change in the atrial mechanical function and determine whether the superior atrial transport function after the RIA is sustained in the long-term postoperative period as well.

In the present study, atrial transport function was evaluated by the diastolic flow-velocity spectra determined by Doppler echocardiography. Diastolic function of the left ventricle also affects the diastolic filling of the ventricle. In this study, there were no significant differences between the groups in age, functional class of heart failure, or aortic cross-clamp time, which might affect the diastolic function. Therefore, the difference in the diastolic function between the groups might be insignificant. In fact, the mitral deceleration time, which is the best single measurement of chamber stiffness [15], did not differ significantly between the procedures. Thus, the difference in the atrial transport function between the procedures may be the result of the difference in the mechanical atrial contraction between the procedures.

The mechanism involved in the superior left atrial transport function of the RIA has been examined in the experimental study using normal canines [5]. Because the atrial incisions of the RIA parallel the major directions of activation wavefronts and atrial coronary arteries, the procedure preserves a more synchronized left atrial activation sequence and the blood supply to most atrial segments. In addition, the posterior left atrium, which the maze procedure isolates, was preserved in the RIA. Although a postoperative mapping study or atrial coronary arteriography was not performed in this clinical study, the mechanism for the superior left atrial transport function may be the same as observed in the canine study.

Both the RIA and maze procedure equally cured AF in the majority of the patients. The success rate for conversion of AF by the maze procedure was similar to the success rate previously described in patients with valvular heart disease [2]. The rationale for surgery for AF is that the lines of conduction block interrupt all the potential macroreentrant pathways and block the fibrillatory wavelets by narrowing the atrial tissue [16]. Left atrial size has been shown to be the most important factor in predisposing patients to persistent AF after the maze procedure [17]. Also, in this study, the patients who did not resume sinus rhythm after the RIA or maze procedure had a larger atrium than the patients who resumed sinus rhythm postoperatively. The RIA recruits the posterior left atrium as a contractile atrial component, resulting in a larger area of atrial tissue in the posterior left atrium to be activated than the maze procedure. Theoretically, the patients after the RIA should be more prone to AF recurrence postoperatively than after the maze procedure. Patients with a severely dilated left atrium are more prone to AF recurrence after the RIA, because the activation wavelets may reciprocate within the dilated posterior left atrium between the pulmonary vein orifices. In 1 patient who was not cured of AF by the RIA, the preoperative LAD was 70 mm measured by echocardiography preoperatively. A severely dilated left atrium with a broad space between the pulmonary vein orifices was confirmed intraoperatively in this patient. Application of an additional incision or a cryolesion to the posterior left atrium may be helpful in preventing AF recurrence in patients with a severely dilated left atrium.

Recently, microreentry and automatic activity arising from one pulmonary vein orifice have been shown to be potential sources for AF in certain patients [6]. Therefore, the procedure was modified from the original RIA procedure for normal canines in order to block the activation propagating from the pulmonary vein orifices in patients. Each pulmonary vein orifice was cryoablated circumferentially as described in "Patients and Methods." This modification confines any reentrant or automatic activity to the pulmonary veins distal to the cryolesions. Although intraoperative mapping was not performed in this study, we believe it is extremely important to eliminate all the possible mechanisms or sources for AF in the surgery for AF. Ablation of pulmonary vein orifices by radiofrequency energy delivered through a catheter has been shown to activate endogenous thrombotic mechanisms [18]. In the present study, 90% of the patients after the RIA were placed on an anticoagulation regimen with coumadin, and none of the patients presented with thrombosis complications involving the left atrium or the pulmonary veins or systemic thromboembolism. Thrombogenicity of endocardial cryothermia in the long-term postoperative period has not been examined in detail. Therefore, patients after circumferential cryothermia of the pulmonary vein orifices should be carefully followed, particularly by echocardiography to find any complications related to the procedure.

One of the goals of the surgery for AF is to alleviate the risk of systemic thromboembolism by preventing blood stasis in the left atrium that leads to the development of mural thrombi. A lower velocity of the blood flow in the left atrial appendage or the posterior left atrium has been shown to increase the risk of thrombus formation and the incidence of stroke [19, 20]. One of the major morbidities after mitral valve replacement involves thromboembolic complications, and the patients with AF have been shown to have a higher incidence of this complication [21]. Restoration of concordant mechanical atrial contraction may prevent the development of mural thrombi. Long-term follow-up of a large number of patients after the RIA is required to reach this conclusion.

Although the aortic cross-clamp time did not show a significant difference between the procedures, the time for cryoablation of all the pulmonary vein orifices extended the aortic cross-clamp time. Since we started to use two cryoprobes and ablate two regions simultaneously, the aortic cross-clamping time significantly decreased during the RIA. We believe that surgery for AF should be performed in most AF patients with or without structural heart disease so that the patients can benefit from the restoration of sinus rhythm and atrial transport function. The RIA is more universally applicable to most patients and provides a greater atrial transport function, and thus can prevent thromboembolism and may represent a physiological alternative to the maze procedure as a surgical procedure for AF. (Fig. 5)

View larger version (55K): [in this window] [in a new window]   Fig 5. The Doppler flow spectra recorded at the left ventricular inflow in patients after the RIA (left) and maze procedure (right). E represents the flow spectrum during the early diastolic filling period and A represents the flow spectrum during atrial filling. Note that large A waves are clearly recognized in the patient after the RIA. Both the patients had undergone mitral valve replacement.

	Footnotes

	References

Top Abstract Introduction Patients and methods Results Comment References

 

1. Cox J.L., Schuessler R.B., Lappas D.G., Boineau J.P. An 8-year clinical experience with surgery for atrial fibrillation. Ann Surg 1996;224:267-273.[Medline]
2. Isobe F., Kawashima Y. The outcome and indications of the Cox maze III procedure for chronic atrial fibrillation with mitral valve disease. J Thorac Cardiovasc Surg 1998;116:220-227.[Abstract/Free Full Text]
3. Feinberg M.S., Waggoner A.D., Kater K.M., Cox J.L., Lindsay B.D., Pèrez J.E. Restoration of atrial function after the maze procedure for patients with atrial fibrillation. Assessment by Doppler echocardiography. Circulation 1994;90(Suppl II):285-292.
4. Nitta T., Lee R., Schuessler R.B., Boineau J.P., Cox J.L. Radial approach. Ann Thorac Surg 1999;67:27-35.[Abstract/Free Full Text]
5. Nitta T., Lee R., Watanabe H., et al. Radial approach. Ann Thorac Surg 1999;67:36-50.[Abstract/Free Full Text]
6. Jaïs P., Haïssaguerre M., Shah D.C., et al. A focal source of atrial fibrillation treated by discrete radiofrequency ablation. Circulation 1997;95:572-576.[Abstract/Free Full Text]
7. Cox J.L., Jaquiss R.D., Schuessler R.B., Boineau J.P. Modification of the 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]
8. Kuo L.C., Quinones M.A., Rokey R., Sartori M., Abinader E.G., Zoghbi W.A. Quantification of atrial contribution to left ventricular filling by pulsed Doppler echocardiography and the effect of age in normal and diseased hearts. Am J Cardiol 1987;59:1174-1178.[Medline]
9. Hartford M., Wikstrand J., Wallentin I., Ljungman S., Wilhelmsen L., Berglund G. Diastolic function of the heart in untreated primary hypertension. Hypertension 1984;6:329-338.[Abstract/Free Full Text]
10. Bonow R.O., Bacharach S.L., Green M.V., et al. Impaired left ventricular diastolic filling in patients with coronary artery disease. Circulation 1981;64:315-323.[Abstract/Free Full Text]
11. Appleton C.P., Hatle L.K., Popp R.L. Relation of transmitral flow velocity patterns to left ventricular diastolic function. J Am Coll Cardiol 1988;12:426-440.[Abstract]
12. Vanoverschelde J.L., Raphael D.A., Robert A.R., Cosyns J.R. Left ventricular filling in dilated cardiomyopathy. J Am Coll Cardiol 1990;15:1288-1295.[Abstract]
13. Klein A.L., Tajik A.J. Doppler assessment of pulmonary venous flow in healthy subjects and in patients with heart disease. J Am Soc Echocardiography 1991;4:379-392.[Medline]
14. 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]
15. Thomas J.D., Newell J.B., Choong C.Y., Weyman A.E. Physical and physiological determinants of transmitral velocity. Am J Physiol 1991;260:H1718-H1731.[Abstract/Free Full Text]
16. Cox J.L., Schuessler R.B., D’Agostino H.J., et al. The surgical treatment of atrial fibrillation. III. Development of a definitive surgical procedure. J Thorac Cardiovasc Surg 1991;101:569-583.[Abstract]
17. Kawaguchi A.T., Kosakai Y., Isobe F., Sasako Y., Eishi K., Nakano K., Takahashi N., Kawashima Y. Factors affecting rhythm after the maze procedure for atrial fibrillation. Circulation 1996;94(Suppl II):139-142.
18. Manolis A.S., Melita-Manolis H., Vassilikos V., Maounis T., Chiladakis J., Christopoulou-Cokkinou V., Cokkinos D.V. Thrombogenicity of radiofrequency lesions. J Am Coll Cardiol 1996;28:1257-1261.[Abstract]
19. Garcia-Fernandez M.A., Torrecilla E.G., San Roman D., et al. Left atrial appendage Doppler flow patterns. Am Heart J 1992;124:955-961.[Medline]
20. Shively B.K., Gelgand E.A., Crawford M.H. Regional left atrial stasis during atrial fibrillation and flutter. J Am Coll Cardiol 1996;27:1722-1729.[Abstract]
21. Edmunds L.H., Jr Thrombotic and bleeding complications of prosthetic heart valves. Ann Thorac Surg 1987;44:430-445.[Abstract]

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