HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

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): Ki-Bong Kim Hyuk Ahn Joon Ryang Rho Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kim, K.-B. Articles by Rho, J. R. Search for Related Content PubMed PubMed Citation Articles by Kim, K.-B. Articles by Rho, J. R.

Ann Thorac Surg 1999;68:799-803
© 1999 The Society of Thoracic Surgeons

---

Original Articles: Cardiovascular

The Cox-Maze III procedure for atrial fibrillation associated with rheumatic mitral valve disease

^a Department of Thoracic and Cardiovascular Surgery, College of Medicine, Seoul National University, Seoul, South Korea
^b Department of Internal Medicine, College of Medicine, Seoul National University, Seoul, South Korea

Address reprint requests to Dr Kim, Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital, 28 Yeun-Kun Dong, Chong-Ro Ku, Seoul 110-744, Korea

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. The surgical results of the Cox-Maze III procedure (CM-III) for atrial fibrillation (AF) associated with rheumatic mitral valve (MV) disease are not as good as the results from surgery for AF alone.

Methods. To assess the efficacy and safety of the CM-III in AF associated with rheumatic MV disease, we retrospectively analyzed 75 patients who underwent the CM-III combined with a rheumatic MV procedure between April 1994 and December 1997. Fourteen cases were reoperations because of prosthetic valve failure.

Results. Mean aortic cross-clamp (ACC) times and cardiopulmonary bypass (CPB) times were 151 ± 43 and 251 ± 73 min, respectively. Concomitant procedures were mitral valve replacement (MVR) in 25 patients, MVR and aortic valve replacement (AVR) in 14 patients, MV repair in 10 patients, MVR and tricuspid annuloplasty (TAP) in 6 patients, MVR and AV repair in 3 patients, MVR and coronary artery bypass grafting (CABG) in 2 patients, MVR and AVR and CABG in 1 patient, redo-MVR in 8 patients, redo-MVR and TAP in 4 patients, and redo-MVR and redo-AVR in 2 patients. There were two in-hospital mortalities (2 of 75, 2.7%). Seventy-three survivors were followed for a mean duration of 30 ± 13 months (12–56 months). Normal sinus rhythm was restored in 90.4% (66 of 73). Three patients remained in AF and 2 patients were in junctional rhythm. Permanent pacemakers were implanted in 2 patients due to sick sinus syndrome. Right atrial (RA) contractility was demonstrable in 100% (66 of 66) and left atrial (LA) contractility in 62.1% (41 of 66) of the patients in the latest follow-up echocardiography. RA and LA contractilities were restored a mean 69 ± 93 and 126 ± 136 days after the operation, respectively. LA contractility was restored significantly later at a lower rate than RA contractility in rheumatic MV disease. There were no differences in ACC time, CPB time, incidence of postoperative bleeding complications, and sinus conversion rates between nonredo and redo cases in spite of the significantly longer duration of preoperative AF in redo cases (p < 0.05).

Conclusions. The CM-III for AF associated with rheumatic MV disease demonstrated a high sinus conversion rate with acceptable operative risk even in cases of reoperation.

	Introduction

Top Abstract Introduction Patients and methods Results Comment References

 
About 40% to 60% of patients who undergo mitral valve (MV) surgery have been reported to be in atrial fibrillation (AF) at the time of operation, and more than 80% of these patients with preoperative chronic AF remained in AF after operations for underlying cardiac diseases [1, 2]. Taking into consideration the potential advantages of maintaining sinus rhythm postoperatively, such as restoration of atrioventricular synchrony and reduction in risk of thromboembolic complications, the decision to use combined procedures to control AF should be made in operations for underlying organic cardiac diseases. The Cox-Maze III procedure (CM-III), initially developed and modified by Cox and associates [3, 4], has become a safe and efficient surgical technique for medically refractory AF. Although the surgical results of the CM-III for lone AF have been proved to be excellent, those for AF associated with MV disease, especially rheumatic MV disease, have been reported to be less effective [5–7]. The aims of this study were: 1) to assess the efficacy of the CM-III for AF associated with rheumatic MV disease, and 2) to demonstrate the safety of the CM-III in a combined procedure including cases involving reoperation.

	Patients and methods

Top Abstract Introduction Patients and methods Results Comment References

 
Between April 1994 and December 1997, 75 patients underwent the CM-III for AF combined with procedures to correct rheumatic MV disease. There were 25 men (33.3%) and 50 women (66.7%), with a mean age of 48 ± 10 years (range 27 to 71 years). Fourteen cases were reoperations because of prosthetic valve failure. Our indications to perform the concomitant CM-III were chronic AF of more than 1 year duration before the operation, presence of left atrial (LA) thrombi, or medical history of previous thromboembolic events. We diagnosed the rheumatic MV disease based on past medical history of rheumatic fever, intraoperative findings of MV defects, or morphologic evaluation of operatively excised MV in case of mitral valve replacement (MVR). The duration of AF was defined as the months between the earliest date when AF was reliably documented in the medical records and the operation date, and the mean duration of AF before the operation was 67 ± 71 months (range 1 to 300 months). Fourteen patients had past medical history of thromboembolic complications, and LA thrombi were identified in 25 patients during the operation. The mean size of the LA on preoperative transthoracic echocardiography (TTE) was 58 ± 11 mm (range 30 to 107 mm). Informed consent was obtained from all patients, including the possible benefits and risks after the combined procedure.

Surgical procedure
The CM-III concomitant with valvular operation was performed under cardiopulmonary bypass (CPB) with moderate hypothermia (25°C–28°C). We performed the CM-III in the manner that Cox and associates [4] had described previously. We used antegrade blood cardioplegia for induction and maintenance of the cardiac arrest in 51 patients, both antegrade and retrograde blood cardioplegia in 21 patients, and retrograde cardioplegia only in 3 patients. We also used warm blood cardioplegia just before releasing the aortic cross-clamp (ACC) in all patients.

Postoperative follow-up
Electrocardiogram (ECG) was continuously monitored during the patient’s stay in the intensive care unit, and the standard 12-lead ECG was checked daily during the postoperative hospital stay, and in the 1st, 3rd, 6th, 12th, 18th, and 24th postoperative months thereafter. To evaluate cardiac function and the recovery of the atrial contraction, TTE was performed before discharge, and in the 1st, 3rd, 6th, 12th, 18th, and 24th postoperative months.

Statistical analysis
Statistical analysis was performed with the Statistical Analysis System software package (version 6.12; SAS Institute, Cary, NC). The predisposing factors associated with persisting AF and recovery of LA contractility were assessed by univariate (², t test) and multivariate analysis (logistic regression analysis). The significance of differences between the right and left atrial contractilities, and that between the nonredo and redo cases, were assessed by nonparametric t test and ² test. All results were expressed as mean ± standard deviation, and a value of p less than 0.05 was considered statistically significant.

	Results

Top Abstract Introduction Patients and methods Results Comment References

 
Operative data
Mean ACC times and CPB times were 151 ± 43 and 251 ± 73 min, respectively. Concomitant procedures were MVR in 25 patients, MVR and aortic valve replacement (AVR) in 14 patients, MV repair in 10 patients, MVR and tricuspid annuloplasty (TAP) in 6 patients, MVR and AV repair in 3 patients, MVR and coronary artery bypass grafting (CABG) in 2 patients, MVR and AVR and CABG in 1 patient, redo-MVR in 8 patients, redo-MVR and TAP in 4 patients, and redo-MVR and redo-AVR in 2 patients (Table 1). In most of the patients who underwent valve replacement, St. Jude mechanical valves (St. Jude Medical, St. Paul, MN) were used, and in elderly patients (> 65 years old) who underwent valve replacement, Carpentier-Edwards pericardial tissue valves (Carpentier-Edwards, Horw, Switzerland) were used.

	Comment

Top Abstract Introduction Patients and methods Results Comment References

The CM-III, the latest modification of the maze procedure, is currently regarded as the technique of choice for the management of medically refractory AF. Cox and associates [3, 8] demonstrated that the CM-III patients had revealed a higher incidence of postoperative sinus rhythm, less arrhythmia recurrence, and improved atrial transport function than patients who underwent either the maze I or maze II procedure in a series consisting mainly of patients with lone AF. They demonstrated that 75% of the patients were in normal sinus rhythm, 25% were atrially paced, and none were in AF postoperatively, resulting in a 100% restoration rate of atrioventricular synchrony. However, the surgical results for AF associated with MV disease, especially rheumatic MV disease, have been reported to be less effective [5–7]. Kosakai and associates [5] demonstrated that 83% of the patients with rheumatic MV disease regained atrial rhythm. Fukada and associates [6] showed that only 45% of the patients with rheumatic MV disease regained atrial rhythm, and they even suggested that the indications for the maze procedure for AF associated with rheumatic MV disease might be reconsidered. The lower sinus conversion rate is assumed to derive from rheumatic changes to the atrial wall or degeneration of atrial tissue resulting from pressure and volume overloading that occurs in valvular heart disease, rather than modification of the maze procedure [5, 9]. Two other probable explanations for failure of sinus conversion are sinus node dysfunction that requires atrial pacemaker implantation, and AF presumably resulting from a shorter atrial refractory time or microreentry [10]. Fukada and associates [6] even suggested that the indications for performing the maze procedure for AF associated with rheumatic MV disease might be reconsidered because of the procedure’s low rate of sinus conversion and atrial contractility. Our study showed that 90.4% of the patients were in normal sinus rhythm and only 4.1% were in AF when all the survivors were followed up more than 1 year. This result suggests that AF can be cured with a high rate of success even in AF associated with rheumatic MV disease. We analyzed the patient histories for predisposing factors for persisting AF, such as advanced age, long history of AF, and increased LA size. In 3 patients with persistent AF, however, no variables were found that would have negative effects on atrial defibrillation. This might result from the small sample size for persistent AF in our group, which could preclude valid statistical comparison.

One of the important advantages of the CM-III for AF is preservation of atrial transport function, thereby decreasing the vulnerability to thromboembolic complication. Cox and associates [3] demonstrated that preservation of atrial transport function was 93.6% in the RA and 85.1% in the LA after the CM-III when evaluated by TTE, although when additional evaluations such as transesophageal echocardiography, atrial versus ventricular pacing, or magnetic resonance imaging were performed, preservation of transport function was 98% in the RA and 94% in the LA after the CM-III. Considering that any of those tests could give a false-negative result, data for atrial transport function need to be carefully interpreted according to the modalities performed. Feinberg and associates [11] demonstrated that LA contraction was detected at a lower rate of 61% and was reduced in magnitude compared with RA contraction, and suggested that the reduced magnitude of LA contraction may be related to delayed interatrial conduction resulting in less than optimal left atrioventricular synchronization or a tethering effect of the posterior wall of the LA. The restoration rate of LA contractility has been reported to be lower and further reduced in patients with rheumatic MV disease than nonrheumatic disease, because the LA wall has been not only thickened or calcified by the influence of rheumatic disease, but also enlarged and degenerated by pressure and volume overloading in valvular disease [5, 6, 9]. Our study revealed that RA contractility was demonstrable in 100% and LA contractility in 62.1% of the patients in the latest follow-up TTE, showing a comparable result with Feinberg’s study performed in nonrheumatic patients. Our results suggested that comparable restoration of atrial contractility might be anticipated even in AF associated with rheumatic MV disease. We also analyzed the patient histories for predisposing factors associated with restoration of LA contractility, and showed that duration of AF shorter than 60 months and recovery of RA contractility within 60 days postoperatively were statistically significant factors that might predict the restoration of LA contractility. The recovery of atrial contractility has been demonstrated to occur later after atrial defibrillation, and recovery of LA contractility has been reported even later than that of RA contractility [12, 13]. The mechanisms of atrial dysfunction after cardioversion of AF have been suggested as postischemic stunning of atrial myocardium [14], or disuse atrophy or hypotrophy of atrial muscle in chronic AF of more than 5 years duration in rheumatic MV disease [15]. Considering the additional surgical factors, such as multiple atrial incisions, sutures, tissue edema, and subsequent scarring after the CM-III, the depression of atrial contractility in the early postoperative period may be anticipated. Shyu and associates [13] suggested that LA contractility recovered later than RA contractility because the LA was generally more influenced by the rheumatic inflammatory process and MV disease than the RA. Our study demonstrated that RA and LA contractilities were restored 69 and 126 days after the operation on an average, respectively, and suggested that the recovery of LA contractility occurred about 2 months later than that of RA contractility even though normal sinus rhythm was regained. As postoperative recurrence of AF was common and atrial contractilities might not be demonstrable during the first 2 months postoperatively, we recommended to our patients who had undergone MV repair or MVR using a bioprosthetic valve that anticoagulation be continued at least 3 or more months postoperatively even if the rhythm was sinus and there had been no thromboembolic events. Although the reduced magnitude of LA contractility was also demonstrated by our group [16], we expected the vulnerability of thromboembolic events to be minimized because the LA auricle, the main site of thrombi formation, was excised and synchronous contraction of the LA with the left ventricle was restored, regardless of the strength of the contraction [3]. We had no experience of late thromboembolic complications in 73 survivors, with a mean follow-up of 30 ± 13 months.

With increasing experience, the indications for the CM-III can be expanded to include redo operations. However, Kobayashi and associates [10] suggested that the maze procedure should be performed in selected patients with a high probability of sinus conversion during redo operations because of the lower sinus conversion rate and significantly longer ACC and CPB times. When we compared our nonredo with redo cases, there were no differences in ACC time, CPB time, incidence of postoperative bleeding complications, and sinus conversion rates in spite of the significantly longer duration of preoperative AF in redo cases. Because we have not found any predisposing factors for persisting AF after the CM-III, we are expanding the indications for the CM-III to include redo operations if patients are judged able to tolerate extended ACC and CPB times.

	References

Top Abstract Introduction Patients and methods Results Comment References

 

1. Chua Y.L., Schaff H.V., Orszulak T.A., Morris J.J. Outcome of mitral valve repair in patients with preoperative atrial fibrillation. J Thorac Cardiovasc Surg 1994;107:408-415.[Abstract/Free Full Text]
2. Kawaguchi A.T., Kosakai Y., Sasako Y., Eishi K., Nakano K., Kawashima Y. Risks and benefits of combined maze procedure for atrial fibrillation associated with organic heart disease. J Am Coll Cardiol 1996;28:985-990.[Abstract]
3. Cox J.L., Boineau J.P., Schuessler R.B., Jaquiss R.D.B., Lappas D.G. Modification of the maze procedure for atrial flutter and atrial fibrillation. I. Rationale and surgical results. J Thorac Cardiovasc Surg 1995;110:473-484.[Abstract/Free Full Text]
4. Cox J.L., Jaquiss R.D.B., 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]
5. Kosakai Y., Kawaguchi A.T., Isobe F., et al. Cox maze procedure for chronic atrial fibrillation associated with mitral valve disease. J Thorac Cardiovasc Surg 1994;108:1049-1055.[Abstract/Free Full Text]
6. 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]
7. Izumoto H., Kawazoe K., Kitahara H., Kamata J. Operative results after the Cox/Maze procedure combined with a mitral valve operation. Ann Thorac Surg 1998;66:800-804.[Abstract/Free Full Text]
8. Cox J.L., Schuessler R.B., Lappas D.G., Boineau J. An 8 -year clinical experience with surgery for atrial fibrillation. Ann Surg 1966;224:267-275.
9. 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]
10. Kobayashi J., Kosakai Y., Isobe F., et al. Rationale of the Cox maze procedure for atrial fibrillation during redo mitral valve operations. J Thorac Cardiovasc Surg 1996;112:1216-1222.[Abstract/Free Full Text]
11. Feinberg M.S., Waggoner A.D., Kater K.M., Cox J.L., Lindsay B.D., Perez J.E. Restoration of atrial function after the maze procedure for patients with atrial fibrillation. Circulation 1994;90(II):285-292.
12. Manning W.J., Leeman D.E., Gotch P.J., Come P.C. Pulsed Doppler evaluation of atrial mechanical function after electrical cardioversion of atrial fibrillation. J Am Coll Cardiol 1989;13:617-623.[Abstract]
13. Shyu K.-G., Cheng J.-J., Chen J.-J., et al. Recovery of atrial function after atrial compartment operation for chronic atrial fibrillation in mitral valve disease. J Am Coll Cardiol 1994;24:392-398.[Abstract]
14. Shapiro E.P., Effron M.B., Lima S., Ouyang P., Siu C.O., Bush D. Transient atrial dysfunction after conversion of chronic atrial fibrillation to sinus rhythm. Am J Cardiol 1988;62:1202-1207.[Medline]
15. Bailey G.W.H., Braniff B.A., Hancock E.W., Cohn K.E. Relation of left atrial pathology to atrial fibrillation in mitral valvular disease. Ann Int Med 1968;69:13-20.
16. 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]

This article has been cited by other articles:

				S. Lonnerholm, P. Blomstrom, L. Nilsson, and C. Blomstrom-Lundqvist Long-Term Effects of the Maze Procedure on Atrial Size and Mechanical Function Ann. Thorac. Surg., March 1, 2008; 85(3): 916 - 920. [Abstract] [Full Text] [PDF]

				K.-B. Kim Reply to Villa et al. Eur. J. Cardiothorac. Surg., August 1, 2007; 32(2): 399 - 399. [Full Text] [PDF]

				K. C. Kim, K. R. Cho, Y.-J. Kim, D.-W. Sohn, and K.-B. Kim Long-term results of the Cox-Maze III procedure for persistent atrial fibrillation associated with rheumatic mitral valve disease: 10-year experience Eur. J. Cardiothorac. Surg., February 1, 2007; 31(2): 261 - 266. [Abstract] [Full Text] [PDF]

				P. K.E.W. Ballaux, G. S.C. Geuzebroek, N. M. van Hemel, J. C. Kelder, K. M.E. Dossche, J. M.P.G. Ernst, L. V.A. Boersma, E. F.D. Wever, A. B. de la Riviere, and J. J.A.M.T. Defauw Freedom from atrial arrhythmias after classic maze III surgery: A 10-year experience J. Thorac. Cardiovasc. Surg., December 1, 2006; 132(6): 1433 - 1440. [Abstract] [Full Text] [PDF]

				S. D. Barnett and N. Ad Surgical ablation as treatment for the elimination of atrial fibrillation: A meta-analysis J. Thorac. Cardiovasc. Surg., May 1, 2006; 131(5): 1029 - 1035. [Abstract] [Full Text] [PDF]

				H.-K. Kim, Y.-J. Kim, K.-I. Kim, S.-H. Jo, K.-B. Kim, H. Ahn, D.-W. Sohn, B.-H. Oh, M.-M. Lee, Y.-B. Park, et al. Impact of the Maze Operation Combined With Left-Sided Valve Surgery on the Change in Tricuspid Regurgitation Over Time Circulation, August 30, 2005; 112(9_suppl): I-14 - I-19. [Abstract] [Full Text] [PDF]

				A. Vora, D. Karnad, V. Goyal, A. Naik, A. Gupta, Y. Lokhandwala, H. Kulkarni, and B. N. Singh Control of Heart Rate Versus Rhythm in Rheumatic Atrial Fibrillation: A Randomized Study Journal of Cardiovascular Pharmacology and Therapeutics, April 1, 2004; 9(2): 65 - 73. [Abstract] [PDF]

				H. T. Sie, W. P. Beukema, A. Elvan, and A. R. Ramdat Misier Long-term results of irrigated radiofrequency modified maze procedure in 200 patients with concomitant cardiac surgery: six years experience Ann. Thorac. Surg., February 1, 2004; 77(2): 512 - 517. [Abstract] [Full Text] [PDF]

				E. R. Jessurun, J. M. T. de Bakker, N. M. van Hemel, T. Opthof, A. C. Linnenbank, P. F. H. M. van Dessel, J. J. A. M. T. Defauw, and A. B. de la Riviere Right atrial modification of maze surgery does not affect refractoriness and conduction patterns of human lone atrial fibrillation Europace, January 1, 2003; 5(1): 39 - 46. [Abstract] [PDF]

				S. Benussi, S. Nascimbene, E. Agricola, G. Calori, S. Calvi, A. Caldarola, M. Oppizzi, V. Casati, C. Pappone, and O. Alfieri Surgical ablation of atrial fibrillation using the epicardial radiofrequency approach: mid-term results and risk analysis Ann. Thorac. Surg., October 1, 2002; 74(4): 1050 - 1057. [Abstract] [Full Text] [PDF]

				H. Nakajima, J. Kobayashi, K. Bando, K. Niwaya, O. Tagusari, Y. Sasako, T. Nakatani, and S. Kitamura The Effect of Cryo-Maze Procedure on Early and Intermediate Term Outcome in Mitral Valve Disease: Case Matched Study Circulation, September 24, 2002; 106(12_suppl_1): I-46 - I-50. [Abstract] [Full Text] [PDF]

				Y. Guang, C. Zhen-jie, L. Wei Yong, L. Tong, and L. Ying Evaluation of clinical treatment of atrial fibrillation associated with rheumatic mitral valve disease by radiofrequency ablation Eur. J. Cardiothorac. Surg., February 1, 2002; 21(2): 249 - 254. [Abstract] [Full Text] [PDF]

				S. Lonnerholm, P. Blomstrom, L. Nilsson, and C. Blomstrom-Lundqvist Atrial size and transport function after the Maze III procedure for paroxysmal atrial fibrillation Ann. Thorac. Surg., January 1, 2002; 73(1): 107 - 111. [Abstract] [Full Text] [PDF]

				S. S. Kabbani, H. Jamil, A. Hammoud, F. Nabhani, R. Hariri, N. Sabbagh, and D. N. Ross Use of the pulmonary autograft for mitral replacement: short- and medium-term experience Eur. J. Cardiothorac. Surg., August 1, 2001; 20(2): 257 - 261. [Abstract] [Full Text] [PDF]

				H. T. Sie, W. P. Beukema, A. R. R. Misier, A. Elvan, J. J. Ennema, M. M.P. Haalebos, and H. J.J. Wellens Radiofrequency modified maze in patients with atrial fibrillation undergoing concomitant cardiac surgery J. Thorac. Cardiovasc. Surg., August 1, 2001; 122(2): 249 - 256. [Abstract] [Full Text] [PDF]

				H. T. Sie, W. P. Beukema, A. R. Ramdat Misier, A. Elvan, J. J. Ennema, and H. J.J. Wellens The radiofrequency modified maze procedure. A less invasive surgical approach to atrial fibrillation during open-heart surgery Eur. J. Cardiothorac. Surg., April 1, 2001; 19(4): 443 - 447. [Abstract] [Full Text] [PDF]

				K.-B. Kim, J.-H. Huh, C. H. Kang, H. Ahn, and D.-W. Sohn Modifications of the Cox-Maze III procedure Ann. Thorac. Surg., March 1, 2001; 71(3): 816 - 822. [Abstract] [Full Text] [PDF]

				S. S. Kabbani Is an optimal mitral substitute within reach? Ann. Thorac. Surg., June 1, 2000; 69(6): 1651 - 1652. [Full Text] [PDF]

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): Ki-Bong Kim Hyuk Ahn Joon Ryang Rho Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kim, K.-B. Articles by Rho, J. R. Search for Related Content PubMed PubMed Citation Articles by Kim, K.-B. Articles by Rho, J. R.