- Email: [email protected]
Prevalence of Arrhythmias Late After the Fontan Operation
Prevalence of Arrhythmias Late After the Fontan Operation Javier J. Lasa, MDa,*, Andrew C. Glatz, MD, MSCEa, Ankana Daga, MDb, and Maully Shah, MBBSa The extracardiac conduit (ECC) modification of the Fontan procedure has been theorized to reduce the risk of sinus node dysfunction and atrial arrhythmia compared with the intraatrial lateral tunnel (ILT) Fontan. This study aimed to compare the prevalence of early and late arrhythmias in patients who underwent ECC and ILT Fontan from a similar era with long-term follow-up at a single institution. A retrospective cohort study was conducted of all patients who underwent ECC or ILT Fontan from 1995 to 2005 at The Children’s Hospital of Philadelphia. Bradyarrhythmias (including sinus node dysfunction), tachyarrhythmias, and pacemaker burden prevalence was determined throughout early (<30 days) and late (>30 days) postoperative periods. Of 434 patients undergoing the Fontan procedure during the study period, a total of 87 and 106 patients who underwent ECC and ILT Fontan, respectively, met the inclusion criteria. There were no significant differences in risk of sinus node dysfunction or tachyarrhythmia in both early and late postoperative periods. Although the overall risk of late postoperative pacemaker therapy was lower for the ECC cohort (4.9% vs 15.7%, p [ 0.03), when adjusting for follow-up time, no significant difference was observed (odds ratio 3.1, 95% confidence interval 0.6 to 15.2, p [ 0.16). In conclusion, the overall prevalence of late postoperative arrhythmias observed after contemporary Fontan modifications is low. Intra-atrial reentrant tachycardia, a potentially fatal complication of the atriopulmonary Fontan operation was infrequently encountered in both ECC and ILT Fontan cohorts. Pacemaker use was higher in the ILT group, although this difference may be explained by differences in follow-up time. Despite the low prevalence of arrhythmias after contemporary Fontan modifications, ongoing surveillance is warranted as the onset of arrhythmias may emerge after longer follow-up time. Ó 2014 Elsevier Inc. All rights reserved. (Am J Cardiol 2014;113:1184e1188)
Postoperative arrhythmias after the Fontan operation have been described since the procedure was introduced in 1971.1,2 Currently, the 2 most commonly employed surgical forms of the total cavopulmonary connection are the intra-atrial lateral tunnel (ILT) and the extracardiac conduit (ECC). For more than a decade, the ECC connection has been the preferred Fontan modification in several institutions,3e5 yet comparative data on the incidence of arrhythmias after ILT and ECC have been limited and controversial.6e10 The ECC Fontan procedure has been theorized to reduce the risk of sinus node dysfunction (SND) and atrial arrhythmia compared with ILT Fontan because of the avoidance of extensive atrial suture lines and exclusion of the atrial chamber from elevated systemic venous pressure. Yet previous injury of the crista terminalis, large atrial wall incisions at the time of intracardiac procedures, and multiple-stage operations may predispose patients to atrial arrhythmias after the ECC Fontan procedure as well. Recent attempts to define rhythm status in this population have included patients with the traditional atriopulmonary form of the Fontan procedure. Yet results a
Division of Cardiology, The Children’s Hospital of Philadelphia, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania and b Department of Pediatric and Adolescent Medicine, Einstein Medical Center, Philadelphia, Pennsylvania. Manuscript received September 19, 2013; revised manuscript received and accepted December 18, 2013. See page 1188 for disclosure information. *Corresponding author: Tel: (215) 590-7430; fax: (215) 590-5825. E-mail address: [email protected] (J.J. Lasa). 0002-9149/14/$ - see front matter Ó 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.amjcard.2013.12.025
from studies such as the Pediatric Heart Network Fontan Cross-Sectional Study demonstrate a disproportionate arrhythmia burden for this older subset of patients who underwent the Fontan procedure, thereby making results difficult to interpret in the current era.6,8 Although additional investigations have excluded patients who underwent traditional atriopulmonary Fontan, these studies are also limited in their lack of sufficient follow-up time and insufficient statistical power for identification of arrhythmia predictors.1,9e12 From 1995 to 2005, The Children’s Hospital of Philadelphia cardiothoracic surgical experience evolved to include an overall balance of ECC and ILT modifications, performed in parallel, without using the traditional atriopulmonary Fontan procedures. We sought to better define the prevalence of arrhythmias in this population while comparing differences in arrhythmias and pacemaker burden between the 2 most commonly employed modifications of the Fontan procedure in the current era. Methods The medical and surgical records of all patients undergoing Fontan palliation from January 1, 1995 to December 31, 2005 at The Children’s Hospital of Philadelphia were reviewed retrospectively. The Institutional Review Board approved this study. Inclusion criteria for this study included (1) presence of the ILT or ECC Fontan procedure, (2) follow-up at The Children’s Hospital of Philadelphia, and (3) electrocardiographic testing within 2 years before www.ajconline.org
Arrhythmias and Conduction Disturbances/Arrhythmias After Fontan Operation
the termination of data collection. Additionally, patients were required to have at least one 15-lead electrocardiogram before Fontan procedure, 1 in the early postoperative period (<30 days) and 1 in the late postoperative period (>30 days). Supporting electrocardiographic data in the form of Holter monitoring was additive; Holter monitoring was not an inclusion requirement. Exclusion criteria included (1) presence of arrhythmia before ECC or ILT Fontan, (2) previous atriopulmonary Fontan procedure, (3) concomitant arrhythmia surgery at the time of ECC or ILT Fontan procedure, and (4) any patient undergoing transplantation during the follow-up period. Age at Fontan procedure and time from Fontan to the most recent outpatient clinical appointment were evaluated. Additional clinical variables obtained from chart review included ventricular morphology (e.g., right ventricle dominant vs noneright ventricle dominant) and presence of fenestration at the time of Fontan procedure. All available electrocardiographic records and 24- or 48-hour ambulatory Holter monitor recordings were analyzed retrospectively. Any impairment of rhythm origin or conduction was assessed as an arrhythmia. The following groups of rhythm disturbances were defined as bradyarrhythmias: (1) SND, which includes sinus bradycardia, ectopic atrial rhythm or bradycardia, predominant junctional rhythm, or sinus pauses exceeding 2 seconds, and (2) complete heart block. The following groups of rhythm disturbances were defined as tachyarrhythmias: (1) supraventricular tachycardia, which included atrial fibrillation, atrial flutter, ectopic atrial tachycardia, junctional ectopic tachycardia, or atrioventricular (AV) reciprocating tachycardia, and (2) ventricular arrhythmias including ventricular tachycardia and ventricular fibrillation. Rhythm disturbances documented during the early postoperative period (<30 days) were defined as early-onset postoperative arrhythmias, and rhythm disturbances documented during the late postoperative period (>30 days) after Fontan operation were considered late arrhythmias. Data are expressed as mean SD for normally distributed continuous variables, median (range) for skewed continuous variables, and count (percentage of total) for categorical variables. Testing of differences in demographic and clinical data based on Fontan type (ECC vs ILT) was accomplished with either unpaired student t test or Wilcoxon rank sum test for continuous variables and with either Pearson’s chi-square test or Fisher’s exact test for categorical variables, as appropriate. Measures of association between potential predictor variables and the primary outcome variables were determined first by univariate logistic regression. Covariates with p <0.2 in univariate testing were considered for inclusion in a multivariate model to identify factors independently associated with outcomes. Covariates were retained in the final multivariate model if the p value was <0.05 or if they showed evidence for significant confounding or effect modification. Kaplan-Meier event-free analysis was used to compare freedom from important arrhythmia outcomes between Fontan types. Statistical significance was established using a 2-tailed p value of <0.05. All statistical analyses were performed using Stata v10 (StataCorp., College Station, Texas).
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Table 1 Clinical and demographic characteristics of the cohort Characteristic (n ¼ 193)
ECC (n ¼ 87)
ILT (n ¼ 106)
p Value
Men 51 (59) 67 (63) Age at Fontan (yrs) 2.4 (1.0e10.95) 1.9 (1.1e12.4) Follow-up after Fontan (yrs) 7.1 (1.1e15) 10.5 (1.7e15.8) Ventricular morphology Left ventricular 32 (37) 23 (22) Right ventricular 52 (60) 78 (74) Mixed 3 (4) 5 (5)
0.52 0.0002 0.0001 0.07
Data are reported as median (range) or count (% of total).
Results From January 1, 1995 to December 31, 2005, a total of 434 patients underwent Fontan palliation at our institution, with 193 patients (44%) meeting study inclusion criteria (87 ECC [45%] vs 106 ILT [55%]). Patients excluded from this study were those not monitored by our institution (n ¼ 192, 44%), those who underwent Fontan revision (n ¼ 28, 6.4%), those deceased at the time of data collection (n ¼ 11, 2.5%), those with preoperative arrhythmias or pacemakers (n ¼ 9, 2.1%), and those who underwent cardiac transplantation (n ¼ 1). Differences in demographic and clinical variables based on Fontan type are summarized in Table 1. There were no major differences in the lead surgeons for the 2 Fontan groups. Patients who underwent ILT and ECC Fontan underwent Fontan completion at early ages during the 1995 to 2000 era (n ¼ 109): ILT (n ¼ 76) median age 1.81 years (range 1.14 to 12.36) and ECC (n ¼ 33) median age 2.06 years (1.01 to 10.95), p ¼ 0.03. In comparison, age at Fontan procedure during the 2001 to 2005 era (n ¼ 84) was later for both ILT (n ¼ 30, median 2.27 years [1.5 to 3.84]) and ECC (n ¼ 54, median 2.47 [1.48 to 4.66]), p ¼ 0.24. The prevalence of early postoperative arrhythmia and differences based on Fontan type are summarized in Table 2. The prevalence of SND in the early postoperative period was 5.2% (10 of 193) for the entire cohort with no statistically significant difference observed between ECC and ILT groups (4.6% ECC vs 5.7% ILT, p ¼ 0.7). Early tachycardias were observed in 4.7% (9 of 193) of the overall cohort with a greater prevalence in the ECC group, although this difference did not attain statistical significance (8% ECC vs 1.9% ILT, p ¼ 0.06). Junctional ectopic tachycardia was the most common tachycardia observed in the early postoperative period with 83% of all episodes of junctional ectopic tachycardia occurring in the ECC Fontan cohort. Only 2 patients required pacemaker implantation during the early postoperative period (1 ECC vs 1 ILT, p ¼ 0.89). The prevalence of late postoperative arrhythmias and differences based on Fontan type are summarized in Table 2. Univariate analysis revealed a higher risk of late pacemaker implantation in the ILT group compared with the ECC Fontan group (2.3% ECC vs 11.3% ILT, p ¼ 0.03). Two patients underwent early pacemaker placement at 7 and 17 days after Fontan procedure with an additional 14 patients requiring pacemaker during the late postoperative period. Of those patients undergoing late pacemaker implantation, the median time from Fontan procedure to
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Table 2 Prevalence of arrhythmias and pacemaker implantation rates in the early (<30 days) and late (>30 days) postoperative period based on Fontan type Variable
Overall, n ¼ 193 (%)
ECC, n ¼ 87 (%)
ILT, n ¼ 106 (%)
ILT vs ECC, OR (95% CI)
p Value
21 (11) 12 (6) 10 2 9 (5) 1 1 6 1 2 (1)
11 (13) 4 (5) 4 — 7 (8) — 1 5 1 1 (1)
10 (10) 8 (8) 6 2 2 (2) 1 — 1 — 1 (1)
0.72 (0.29e1.8) 1.69 (0.49e5.8) 1.25 (0.4e4.2)
0.48 0.40 0.7
0.22 (0.04e1.09)
0.06
0.82 (0.05e13.3)
0.89
60 (31) 58 (30) 58 1 7 (4) 2 5 1 14 (7)
26 (30) 25 (29) 25 — 3 (3) 1 2 — 2 (2)
34 (32) 33 (31) 32 1 4 (4) 1 3 1 12 (11)
1.11 (0.6e2.1) 1.12 (0.63e2.17)
0.74 0.72
Early arrhythmia or pacemaker All arrhythmia Bradyarrhythmia SND Complete heart block Tachyarrhythmia AV nodal reentrant tachycardia Ectopic atrial tachycardia Junctional ectopic tachycardia Ventricular tachycardia Pacemaker Late arrhythmia or pacemaker Any arrhythmia Bradyarrhythmia* SND Complete heart block Tachyarrhythmia* AV nodal reentrant tachycardia Intra-atrial reentrant tachycardia Junctional ectopic tachycardia Pacemaker
1.1 (0.24e5)
0.9
5.4 (1.2e24.9)
0.03
CI ¼ confidence interval; OR ¼ odds ratio. * Some patients were found to have >1 type of arrhythmia. Table 3 Factors associated with late arrhythmia and pacemaker implantation Variable
Univariate Analysis OR (95% CI)
Late arrhythmia Age at Fontan (yrs) Follow-up from Fontan (yrs) Fontan type (ILT vs ECC) Ventricular morphology (noneright ventricular vs right ventricular) Fenestration Late pacemaker implantation Age at Fontan (yrs) Follow-up from Fontan (yrs) Fontan type (ILT vs ECC) Ventricular morphology (noneright ventricular vs right ventricular) Fenestration
Multivariate Analysis
p Value
1.02 1.14 1.1 1.07 0.5
(0.8e1.3) (1.04e1.24) (0.6e2.1) (0.6e1.8) (0.16e1.6)
0.86 0.004 0.74 0.8 0.23
1.04 1.35 5.4 0.8 0.9
(0.7e1.5) (1.1e1.6) (1.2e24.9) (0.24e2.7) (0.1e7.8)
0.86 0.002 0.03 0.74 0.95
OR (95% CI)
p Value
1.29 (1.06e1.57) 3.1 (0.6e15.2)
0.01 0.16
CI ¼ confidence interval; OR ¼ odds ratio.
pacemaker placement was 2.01 years (range 0.4 to 11.52) with SND as the most common indication for pacemaker implantation. Potential risk factors for arrhythmias and pacemaker implantation in the late postoperative period were identified by univariate logistic regression (see Table 3). Although duration of follow-up from Fontan operation and Fontan type were identifiable risk factors for pacemaker implantation in the late postoperative period on univariate logistic regression, only duration of follow-up (odds ratio 1.29, 95% confidence interval 1.06 to 1.57, for every year of follow-up, p ¼ 0.01) remained an independent predictor of late pacemaker utilization on multivariate testing. Figure 1 shows Kaplan-Meier curves for freedom from pacemaker implantation for both Fontan groups.
Discussion In an effort to expand our current understanding of postoperative arrhythmias in the growing single-ventricle population who have undergone Fontan palliation, our investigation yielded a relatively low prevalence of both SND and tachyarrhythmias at a median follow-up of at least 7 years after Fontan operation. There were no identifiable differences in prevalence of SND or tachyarrhythmia between Fontan groups throughout the late postoperative period. Although patients who underwent ECC Fontan demonstrated lower rates of device implantation on initial univariate analysis, this difference appears to be largely explained by the differential follow-up time, as Fontan type was not significantly associated with odds of pacemaker
Arrhythmias and Conduction Disturbances/Arrhythmias After Fontan Operation
Figure 1. Kaplan-Meier curves demonstrating impact of Fontan type on freedom from pacemaker.
utilization after adjusting for duration of follow-up in a multivariate regression model. Previously published reports have included small Fontan cohorts (ranging from 35 to 165 patients), short duration of follow-up, unequal distribution of Fontan types, or insufficient statistical power for identification of arrhythmia predictors.4,10,12e15 Nurnberg et al9 studied 29 patients with ILT and compared them with 45 patients with ECC. They found a greater likelihood of pacemaker implantation and propensity to develop supraventricular tachyarrhythmias in patients who underwent ILT compared with ECC Fontan.9 In one of the larger studies to date, Fiore et al12 evaluated 162 patients with Fontan modifications (49 ECC vs 113 ILT). The frequency of postoperative nonsinus rhythm (ECC 15% vs ILT 18%) and the need for permanent pacemaker insertion (ECC 9% vs ILT 10%) were similar in both groups. However, in a study involving similar patient numbers, Lee et al16 reported that patients who underwent ILT had a greater incidence of nonsinus rhythm compared with ECC (ECC 11% vs ILT 22%). Surprisingly, a smaller study consisting of 54 patients by Dilawar et al10 reported an increase in the incidence of SND in the ECC group compared with the ILT group (ECC 59% vs 21%). Recently, the Pediatric Heart Network investigators published 2 reports on a large cohort of patients who underwent Fontan operation describing the functional status, heart rate, and rhythm abnormalities in 521 patients ranging in age from 6 to 18 years.6,8 Despite the large cohorts analyzed, these studies did not address the question of difference in arrhythmia prevalence or pacemaker burden between the ILT and ECC subsets of patients with the Fontan procedure. As in our study, these investigators also found a preponderance of patients who underwent ILT compared with ECC Fontan (24% ECC vs 59% ILT), whereas the remainder of the patients had an atriopulmonary type of Fontan procedure. Furthermore, it is unclear from these studies as to the postoperative follow-up period for the patients who underwent ECC and ILT and the time period during which rhythm assessment was performed. These studies also addressed myocardial function and AV valve regurgitation as potential confounding variables in arrhythmogenesis in the Fontan population. The initial evaluation
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published in 2008 found that moderate to severe AV valve regurgitation was more common in children with Fontan performed at >3 years (23% to 26%) compared with children with Fontan performed at <2 or at 2 to <3 years (13% to 16%).8 Most patients in our report underwent Fontan palliation at <3 years of age. Furthermore, the 2010 analysis of arrhythmias in the Fontan population found no significant association between degree of regurgitation and arrhythmias throughout the cohort.6 The postoperative pacemaker burden in the Fontan population has also been described in the literature with pacemaker implantation rates ranging from 0.0% to 7.7%.17e22 These studies have significant limitations including selection bias in those studies focusing on Fontan conversions with concomitant surgical ablation procedures,23,24 institutional preference for single Fontan type,17,20e22 and short follow-up duration.19 The prevalence of tachyarrhythmias we observed is lower than previously published reports and was found to be associated with only duration of follow-up and not the specific type of Fontan modification. Specifically, the absence of any patients who underwent classic atriopulmonary Fontan in this analysis has allowed us to reevaluate the single-ventricle population after Fontan palliation with an improved understanding of arrhythmias in the late term. Patients who have undergone atriopulmonary Fontan have made up a substantial portion of the atrial tachyarrhythmia or intra-atrial reentrant tachycardia burden in historic Fontan cohorts, including the large Pediatric Heart Network studies mentioned previously,6,8 as well as earlier studies evaluating Fontan conversion with combined surgical ablation.23,24 Yet, an overall rate of tachyarrhythmia of 31% is cause for concern and increased vigilance for practitioners caring for patients who undergo Fontan procedure. Strategies to prevent and manage these arrhythmias will assume critical importance for this group of complex patients in the future. In evaluating a more contemporary generation of patients who underwent Fontan operation, we also observed similar rates of SND and tachyarrhythmias between the Fontan modifications employed at our institution over the past 15 years. This was the first study to have similarly distributed cohorts from the same era with consistent operators. Although these factors cannot be measured between institutions in a retrospective fashion, they likely impacted studies that analyzed cohorts of either ECC or ILT Fontan type. Differences in age at Fontan were observed to be significantly different in our analysis. Despite the statistically significant difference in age between ILT and ECC groups, age at Fontan was not a significant predictor of arrhythmias in the regression analysis. It is possible that longer follow-up period may potentially affect our results. Our study has several limitations. Given the retrospective nature of this investigation, the surgical strategy for Fontan palliation reflects the individual operator’s preference as well as patient’s anatomic substrate. In addition, subjects were not randomly allocated to either ECC or ILT Fontan. Therefore, inferences from this study are subject to both selection and survivor bias. Furthermore, the relatively low prevalence of arrhythmias and pacemakers in each Fontan
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group and the relatively small sample size limited further statistical analysis. As outlined in the study design, our analysis was restricted to data from patients with follow-up at our institution only, and comparison with patients who underwent Fontan procedure with postoperative follow-up at other institutions was beyond the scope of this study. Lastly, confounding variables such as ventricular function and presence of AV valve regurgitation may have influenced the prevalence of arrhythmias in our population and were not fully evaluated in this analysis.
Disclosures The authors have no conflicts of interest to disclose. 1. Fontan F, Baudet E. Surgical repair of tricuspid atresia. Thorax 1971;26:240e248. 2. Sharratt GP, Johnson AM, Monro JL. Persistence and effects of sinus rhythm after Fontan procedure for tricuspid atresia. Br Heart J 1979;42: 74e80. 3. Ocello S, Salviato N, Marcelletti CF. Results of 100 consecutive extracardiac conduit Fontan operations. Pediatr Cardiol 2007;28: 433e437. 4. Brown JW, Ruzmetov M, Deschner BW, Rodefeld MD, Turrentine MW. Lateral tunnel Fontan in the current era: is it still a good option? Ann Thorac Surg 2010;89:556e563. 5. Vouhé PR. Fontan completion: intracardiac tunnel or extracardiac conduit? Thorac Cardiovasc Surg 2001;49:27e29. 6. Stephenson EA, Lu M, Berul CI, Etheridge SP, Idriss SF, Margossian R, Reed JH, Prakash A, Sleeper LA, Vetter VL, Blaufox AD, Pediatric Heart Network Investigators. Arrhythmias in a contemporary Fontan cohort. J Am Coll Cardiol 2010;56:890e896. 7. Anderson P, Sleeper L, Mahony L, Colan S, Atz A, Breitbart R, Gerson W, Gallagher D, Geva T, Margossian R. Contemporary outcomes after the Fontan procedure: a Pediatric Heart Network multicenter study. J Am Coll Cardiol 2008;52:85e98. 8. Blaufox AD, Sleeper LA, Bradley DJ, Breitbart RE, Hordof A, Kanter RJ, Stephenson EA, Stylianou M, Vetter VL, Saul JP. Functional status, heart rate, and rhythm abnormalities in 521 Fontan patients 6 to 18 years of age. J Thorac Cardiovasc Surg 2008;136:100e107 (e1). 9. Nurnberg J, Ovroutski S, Aleximeskishvili V, Ewert P, Hetzer R, Lange P. New onset arrhythmias after the extracardiac conduit Fontan operation compared with the intraatrial lateral tunnel procedure: early and midterm results. Ann Thorac Surg 2004;78:1979e1988.
10. Dilawar M, Bradley SM, Saul JP, Stroud MR, Balaji S. Sinus node dysfunction after intraatrial lateral tunnel and extracardiac conduit Fontan procedures. Pediatr Cardiol 2003;24:284e288. 11. Azakie A, McCrindle BW, Van Arsdell G, Benson LN, Coles J, Hamilton R, Freedom RM, Williams WG. Extracardiac conduit versus lateral tunnel cavopulmonary connections at a single institution: impact on outcomes. J Thorac Cardiovasc Surg 2001;122:1219e1228. 12. Fiore A, Turrentine M, Rodefeld M, Vijay P, Schwartz T, Virgo K, Fischer L, Brown J. Fontan operation: a comparison of lateral tunnel with extracardiac conduit. Ann Thorac Surg 2007;83:622e630. 13. Van Son J, Mohr F, Hambsch J. Conversion of atriopulmonary or lateral atrial tunnel cavopulmonary anastomosis to extracardiac conduit Fontan modification. Eur J Cardiothorac Surg 1999;15:150e158. 14. Marcelletti C, Corno A, Giannico S, Marino B. Inferior vena cavapulmonary artery extracardiac conduit. A new form of right heart bypass. J Thorac Cardiovasc Surg 1990;100:228e232. 15. Rodefeld MD, Bromberg BI, Schuessler RB, Boineau JP, Cox JL, Huddleston CB. Atrial flutter after lateral tunnel construction in the modified Fontan operation: a canine model. J Thorac Cardiovasc Surg 1996;111:514e526. 16. Lee JR, Kwak J, Kim KC, Min SK, Kim W, Kim YJ, Rho JR. Comparison of lateral tunnel and extracardiac conduit Fontan procedure. Interact Cardiovasc Thorac Surg 2007;6:328e330. 17. Hasaniya NW, Razzouk AJ, Mulla NF, Larsen RL, Bailey LL. In situ pericardial extracardiac lateral tunnel Fontan operation: fifteen-year experience. J Thorac Cardiovasc Surg 2010;140:1076e1083. 18. Kwak JG, Kim W-H, Lee JR, Kim YJ. Surgical therapy of arrhythmias in single-ventricle patients undergoing Fontan or Fontan conversion. J Card Surg 2009;24:738e741. 19. Tweddell JS, Nersesian M, Mussatto KA, Nugent M, Simpson P, Mitchell ME, Ghanayem NS, Pelech AN, Marla R, Hoffman GM. Fontan palliation in the modern era: factors impacting mortality and morbidity. Ann Thorac Surg 2009;88:1291e1299. 20. Hirsch JC, Goldberg C, Bove EL, Salehian S, Lee T, Ohye R, Devaney EJ. Fontan operation in the current era. Ann Surg 2008;126:52e60. 21. Nakano T, Kado H, Tachibana T, Hinokiyama K, Shiose A, Kajimoto M, Ando Y. Excellent midterm outcome of extracardiac conduit total cavopulmonary connection: results of 126 cases. Ann Thorac Surg 2007;84:1619e1626. 22. Giannico S, Hammad F, Amodeo A, Michielon G, Drago F, Turchetta A, Di Donato R, Sanders SP. Clinical outcome of 193 extracardiac Fontan patients. J Am Coll Cardiol 2006;47:2065e2073. 23. Tsao S, Deal BJ, Backer CL, Ward K, Franklin WH, Mavroudis C. Device management of arrhythmias after Fontan conversion. J Thorac Cardiovasc Surg 2009;138:937e940. 24. Mavroudis C, Deal BJ, Backer CL, Steward RD, Franklin WH, Tsao S, Ward KM, Defreitas RA. 111 Fontan conversions with arrhythmia surgery: surgical lessons and outcomes. Ann Thorac Surg 2007:1457e1466.
Postoperative arrhythmias after the Fontan operation have been described since the procedure was introduced in 1971.1,2 Currently, the 2 most commonly employed surgical forms of the total cavopulmonary connection are the intra-atrial lateral tunnel (ILT) and the extracardiac conduit (ECC). For more than a decade, the ECC connection has been the preferred Fontan modification in several institutions,3e5 yet comparative data on the incidence of arrhythmias after ILT and ECC have been limited and controversial.6e10 The ECC Fontan procedure has been theorized to reduce the risk of sinus node dysfunction (SND) and atrial arrhythmia compared with ILT Fontan because of the avoidance of extensive atrial suture lines and exclusion of the atrial chamber from elevated systemic venous pressure. Yet previous injury of the crista terminalis, large atrial wall incisions at the time of intracardiac procedures, and multiple-stage operations may predispose patients to atrial arrhythmias after the ECC Fontan procedure as well. Recent attempts to define rhythm status in this population have included patients with the traditional atriopulmonary form of the Fontan procedure. Yet results a
Division of Cardiology, The Children’s Hospital of Philadelphia, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania and b Department of Pediatric and Adolescent Medicine, Einstein Medical Center, Philadelphia, Pennsylvania. Manuscript received September 19, 2013; revised manuscript received and accepted December 18, 2013. See page 1188 for disclosure information. *Corresponding author: Tel: (215) 590-7430; fax: (215) 590-5825. E-mail address: [email protected] (J.J. Lasa). 0002-9149/14/$ - see front matter Ó 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.amjcard.2013.12.025
from studies such as the Pediatric Heart Network Fontan Cross-Sectional Study demonstrate a disproportionate arrhythmia burden for this older subset of patients who underwent the Fontan procedure, thereby making results difficult to interpret in the current era.6,8 Although additional investigations have excluded patients who underwent traditional atriopulmonary Fontan, these studies are also limited in their lack of sufficient follow-up time and insufficient statistical power for identification of arrhythmia predictors.1,9e12 From 1995 to 2005, The Children’s Hospital of Philadelphia cardiothoracic surgical experience evolved to include an overall balance of ECC and ILT modifications, performed in parallel, without using the traditional atriopulmonary Fontan procedures. We sought to better define the prevalence of arrhythmias in this population while comparing differences in arrhythmias and pacemaker burden between the 2 most commonly employed modifications of the Fontan procedure in the current era. Methods The medical and surgical records of all patients undergoing Fontan palliation from January 1, 1995 to December 31, 2005 at The Children’s Hospital of Philadelphia were reviewed retrospectively. The Institutional Review Board approved this study. Inclusion criteria for this study included (1) presence of the ILT or ECC Fontan procedure, (2) follow-up at The Children’s Hospital of Philadelphia, and (3) electrocardiographic testing within 2 years before www.ajconline.org
Arrhythmias and Conduction Disturbances/Arrhythmias After Fontan Operation
the termination of data collection. Additionally, patients were required to have at least one 15-lead electrocardiogram before Fontan procedure, 1 in the early postoperative period (<30 days) and 1 in the late postoperative period (>30 days). Supporting electrocardiographic data in the form of Holter monitoring was additive; Holter monitoring was not an inclusion requirement. Exclusion criteria included (1) presence of arrhythmia before ECC or ILT Fontan, (2) previous atriopulmonary Fontan procedure, (3) concomitant arrhythmia surgery at the time of ECC or ILT Fontan procedure, and (4) any patient undergoing transplantation during the follow-up period. Age at Fontan procedure and time from Fontan to the most recent outpatient clinical appointment were evaluated. Additional clinical variables obtained from chart review included ventricular morphology (e.g., right ventricle dominant vs noneright ventricle dominant) and presence of fenestration at the time of Fontan procedure. All available electrocardiographic records and 24- or 48-hour ambulatory Holter monitor recordings were analyzed retrospectively. Any impairment of rhythm origin or conduction was assessed as an arrhythmia. The following groups of rhythm disturbances were defined as bradyarrhythmias: (1) SND, which includes sinus bradycardia, ectopic atrial rhythm or bradycardia, predominant junctional rhythm, or sinus pauses exceeding 2 seconds, and (2) complete heart block. The following groups of rhythm disturbances were defined as tachyarrhythmias: (1) supraventricular tachycardia, which included atrial fibrillation, atrial flutter, ectopic atrial tachycardia, junctional ectopic tachycardia, or atrioventricular (AV) reciprocating tachycardia, and (2) ventricular arrhythmias including ventricular tachycardia and ventricular fibrillation. Rhythm disturbances documented during the early postoperative period (<30 days) were defined as early-onset postoperative arrhythmias, and rhythm disturbances documented during the late postoperative period (>30 days) after Fontan operation were considered late arrhythmias. Data are expressed as mean SD for normally distributed continuous variables, median (range) for skewed continuous variables, and count (percentage of total) for categorical variables. Testing of differences in demographic and clinical data based on Fontan type (ECC vs ILT) was accomplished with either unpaired student t test or Wilcoxon rank sum test for continuous variables and with either Pearson’s chi-square test or Fisher’s exact test for categorical variables, as appropriate. Measures of association between potential predictor variables and the primary outcome variables were determined first by univariate logistic regression. Covariates with p <0.2 in univariate testing were considered for inclusion in a multivariate model to identify factors independently associated with outcomes. Covariates were retained in the final multivariate model if the p value was <0.05 or if they showed evidence for significant confounding or effect modification. Kaplan-Meier event-free analysis was used to compare freedom from important arrhythmia outcomes between Fontan types. Statistical significance was established using a 2-tailed p value of <0.05. All statistical analyses were performed using Stata v10 (StataCorp., College Station, Texas).
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Table 1 Clinical and demographic characteristics of the cohort Characteristic (n ¼ 193)
ECC (n ¼ 87)
ILT (n ¼ 106)
p Value
Men 51 (59) 67 (63) Age at Fontan (yrs) 2.4 (1.0e10.95) 1.9 (1.1e12.4) Follow-up after Fontan (yrs) 7.1 (1.1e15) 10.5 (1.7e15.8) Ventricular morphology Left ventricular 32 (37) 23 (22) Right ventricular 52 (60) 78 (74) Mixed 3 (4) 5 (5)
0.52 0.0002 0.0001 0.07
Data are reported as median (range) or count (% of total).
Results From January 1, 1995 to December 31, 2005, a total of 434 patients underwent Fontan palliation at our institution, with 193 patients (44%) meeting study inclusion criteria (87 ECC [45%] vs 106 ILT [55%]). Patients excluded from this study were those not monitored by our institution (n ¼ 192, 44%), those who underwent Fontan revision (n ¼ 28, 6.4%), those deceased at the time of data collection (n ¼ 11, 2.5%), those with preoperative arrhythmias or pacemakers (n ¼ 9, 2.1%), and those who underwent cardiac transplantation (n ¼ 1). Differences in demographic and clinical variables based on Fontan type are summarized in Table 1. There were no major differences in the lead surgeons for the 2 Fontan groups. Patients who underwent ILT and ECC Fontan underwent Fontan completion at early ages during the 1995 to 2000 era (n ¼ 109): ILT (n ¼ 76) median age 1.81 years (range 1.14 to 12.36) and ECC (n ¼ 33) median age 2.06 years (1.01 to 10.95), p ¼ 0.03. In comparison, age at Fontan procedure during the 2001 to 2005 era (n ¼ 84) was later for both ILT (n ¼ 30, median 2.27 years [1.5 to 3.84]) and ECC (n ¼ 54, median 2.47 [1.48 to 4.66]), p ¼ 0.24. The prevalence of early postoperative arrhythmia and differences based on Fontan type are summarized in Table 2. The prevalence of SND in the early postoperative period was 5.2% (10 of 193) for the entire cohort with no statistically significant difference observed between ECC and ILT groups (4.6% ECC vs 5.7% ILT, p ¼ 0.7). Early tachycardias were observed in 4.7% (9 of 193) of the overall cohort with a greater prevalence in the ECC group, although this difference did not attain statistical significance (8% ECC vs 1.9% ILT, p ¼ 0.06). Junctional ectopic tachycardia was the most common tachycardia observed in the early postoperative period with 83% of all episodes of junctional ectopic tachycardia occurring in the ECC Fontan cohort. Only 2 patients required pacemaker implantation during the early postoperative period (1 ECC vs 1 ILT, p ¼ 0.89). The prevalence of late postoperative arrhythmias and differences based on Fontan type are summarized in Table 2. Univariate analysis revealed a higher risk of late pacemaker implantation in the ILT group compared with the ECC Fontan group (2.3% ECC vs 11.3% ILT, p ¼ 0.03). Two patients underwent early pacemaker placement at 7 and 17 days after Fontan procedure with an additional 14 patients requiring pacemaker during the late postoperative period. Of those patients undergoing late pacemaker implantation, the median time from Fontan procedure to
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Table 2 Prevalence of arrhythmias and pacemaker implantation rates in the early (<30 days) and late (>30 days) postoperative period based on Fontan type Variable
Overall, n ¼ 193 (%)
ECC, n ¼ 87 (%)
ILT, n ¼ 106 (%)
ILT vs ECC, OR (95% CI)
p Value
21 (11) 12 (6) 10 2 9 (5) 1 1 6 1 2 (1)
11 (13) 4 (5) 4 — 7 (8) — 1 5 1 1 (1)
10 (10) 8 (8) 6 2 2 (2) 1 — 1 — 1 (1)
0.72 (0.29e1.8) 1.69 (0.49e5.8) 1.25 (0.4e4.2)
0.48 0.40 0.7
0.22 (0.04e1.09)
0.06
0.82 (0.05e13.3)
0.89
60 (31) 58 (30) 58 1 7 (4) 2 5 1 14 (7)
26 (30) 25 (29) 25 — 3 (3) 1 2 — 2 (2)
34 (32) 33 (31) 32 1 4 (4) 1 3 1 12 (11)
1.11 (0.6e2.1) 1.12 (0.63e2.17)
0.74 0.72
Early arrhythmia or pacemaker All arrhythmia Bradyarrhythmia SND Complete heart block Tachyarrhythmia AV nodal reentrant tachycardia Ectopic atrial tachycardia Junctional ectopic tachycardia Ventricular tachycardia Pacemaker Late arrhythmia or pacemaker Any arrhythmia Bradyarrhythmia* SND Complete heart block Tachyarrhythmia* AV nodal reentrant tachycardia Intra-atrial reentrant tachycardia Junctional ectopic tachycardia Pacemaker
1.1 (0.24e5)
0.9
5.4 (1.2e24.9)
0.03
CI ¼ confidence interval; OR ¼ odds ratio. * Some patients were found to have >1 type of arrhythmia. Table 3 Factors associated with late arrhythmia and pacemaker implantation Variable
Univariate Analysis OR (95% CI)
Late arrhythmia Age at Fontan (yrs) Follow-up from Fontan (yrs) Fontan type (ILT vs ECC) Ventricular morphology (noneright ventricular vs right ventricular) Fenestration Late pacemaker implantation Age at Fontan (yrs) Follow-up from Fontan (yrs) Fontan type (ILT vs ECC) Ventricular morphology (noneright ventricular vs right ventricular) Fenestration
Multivariate Analysis
p Value
1.02 1.14 1.1 1.07 0.5
(0.8e1.3) (1.04e1.24) (0.6e2.1) (0.6e1.8) (0.16e1.6)
0.86 0.004 0.74 0.8 0.23
1.04 1.35 5.4 0.8 0.9
(0.7e1.5) (1.1e1.6) (1.2e24.9) (0.24e2.7) (0.1e7.8)
0.86 0.002 0.03 0.74 0.95
OR (95% CI)
p Value
1.29 (1.06e1.57) 3.1 (0.6e15.2)
0.01 0.16
CI ¼ confidence interval; OR ¼ odds ratio.
pacemaker placement was 2.01 years (range 0.4 to 11.52) with SND as the most common indication for pacemaker implantation. Potential risk factors for arrhythmias and pacemaker implantation in the late postoperative period were identified by univariate logistic regression (see Table 3). Although duration of follow-up from Fontan operation and Fontan type were identifiable risk factors for pacemaker implantation in the late postoperative period on univariate logistic regression, only duration of follow-up (odds ratio 1.29, 95% confidence interval 1.06 to 1.57, for every year of follow-up, p ¼ 0.01) remained an independent predictor of late pacemaker utilization on multivariate testing. Figure 1 shows Kaplan-Meier curves for freedom from pacemaker implantation for both Fontan groups.
Discussion In an effort to expand our current understanding of postoperative arrhythmias in the growing single-ventricle population who have undergone Fontan palliation, our investigation yielded a relatively low prevalence of both SND and tachyarrhythmias at a median follow-up of at least 7 years after Fontan operation. There were no identifiable differences in prevalence of SND or tachyarrhythmia between Fontan groups throughout the late postoperative period. Although patients who underwent ECC Fontan demonstrated lower rates of device implantation on initial univariate analysis, this difference appears to be largely explained by the differential follow-up time, as Fontan type was not significantly associated with odds of pacemaker
Arrhythmias and Conduction Disturbances/Arrhythmias After Fontan Operation
Figure 1. Kaplan-Meier curves demonstrating impact of Fontan type on freedom from pacemaker.
utilization after adjusting for duration of follow-up in a multivariate regression model. Previously published reports have included small Fontan cohorts (ranging from 35 to 165 patients), short duration of follow-up, unequal distribution of Fontan types, or insufficient statistical power for identification of arrhythmia predictors.4,10,12e15 Nurnberg et al9 studied 29 patients with ILT and compared them with 45 patients with ECC. They found a greater likelihood of pacemaker implantation and propensity to develop supraventricular tachyarrhythmias in patients who underwent ILT compared with ECC Fontan.9 In one of the larger studies to date, Fiore et al12 evaluated 162 patients with Fontan modifications (49 ECC vs 113 ILT). The frequency of postoperative nonsinus rhythm (ECC 15% vs ILT 18%) and the need for permanent pacemaker insertion (ECC 9% vs ILT 10%) were similar in both groups. However, in a study involving similar patient numbers, Lee et al16 reported that patients who underwent ILT had a greater incidence of nonsinus rhythm compared with ECC (ECC 11% vs ILT 22%). Surprisingly, a smaller study consisting of 54 patients by Dilawar et al10 reported an increase in the incidence of SND in the ECC group compared with the ILT group (ECC 59% vs 21%). Recently, the Pediatric Heart Network investigators published 2 reports on a large cohort of patients who underwent Fontan operation describing the functional status, heart rate, and rhythm abnormalities in 521 patients ranging in age from 6 to 18 years.6,8 Despite the large cohorts analyzed, these studies did not address the question of difference in arrhythmia prevalence or pacemaker burden between the ILT and ECC subsets of patients with the Fontan procedure. As in our study, these investigators also found a preponderance of patients who underwent ILT compared with ECC Fontan (24% ECC vs 59% ILT), whereas the remainder of the patients had an atriopulmonary type of Fontan procedure. Furthermore, it is unclear from these studies as to the postoperative follow-up period for the patients who underwent ECC and ILT and the time period during which rhythm assessment was performed. These studies also addressed myocardial function and AV valve regurgitation as potential confounding variables in arrhythmogenesis in the Fontan population. The initial evaluation
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published in 2008 found that moderate to severe AV valve regurgitation was more common in children with Fontan performed at >3 years (23% to 26%) compared with children with Fontan performed at <2 or at 2 to <3 years (13% to 16%).8 Most patients in our report underwent Fontan palliation at <3 years of age. Furthermore, the 2010 analysis of arrhythmias in the Fontan population found no significant association between degree of regurgitation and arrhythmias throughout the cohort.6 The postoperative pacemaker burden in the Fontan population has also been described in the literature with pacemaker implantation rates ranging from 0.0% to 7.7%.17e22 These studies have significant limitations including selection bias in those studies focusing on Fontan conversions with concomitant surgical ablation procedures,23,24 institutional preference for single Fontan type,17,20e22 and short follow-up duration.19 The prevalence of tachyarrhythmias we observed is lower than previously published reports and was found to be associated with only duration of follow-up and not the specific type of Fontan modification. Specifically, the absence of any patients who underwent classic atriopulmonary Fontan in this analysis has allowed us to reevaluate the single-ventricle population after Fontan palliation with an improved understanding of arrhythmias in the late term. Patients who have undergone atriopulmonary Fontan have made up a substantial portion of the atrial tachyarrhythmia or intra-atrial reentrant tachycardia burden in historic Fontan cohorts, including the large Pediatric Heart Network studies mentioned previously,6,8 as well as earlier studies evaluating Fontan conversion with combined surgical ablation.23,24 Yet, an overall rate of tachyarrhythmia of 31% is cause for concern and increased vigilance for practitioners caring for patients who undergo Fontan procedure. Strategies to prevent and manage these arrhythmias will assume critical importance for this group of complex patients in the future. In evaluating a more contemporary generation of patients who underwent Fontan operation, we also observed similar rates of SND and tachyarrhythmias between the Fontan modifications employed at our institution over the past 15 years. This was the first study to have similarly distributed cohorts from the same era with consistent operators. Although these factors cannot be measured between institutions in a retrospective fashion, they likely impacted studies that analyzed cohorts of either ECC or ILT Fontan type. Differences in age at Fontan were observed to be significantly different in our analysis. Despite the statistically significant difference in age between ILT and ECC groups, age at Fontan was not a significant predictor of arrhythmias in the regression analysis. It is possible that longer follow-up period may potentially affect our results. Our study has several limitations. Given the retrospective nature of this investigation, the surgical strategy for Fontan palliation reflects the individual operator’s preference as well as patient’s anatomic substrate. In addition, subjects were not randomly allocated to either ECC or ILT Fontan. Therefore, inferences from this study are subject to both selection and survivor bias. Furthermore, the relatively low prevalence of arrhythmias and pacemakers in each Fontan
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group and the relatively small sample size limited further statistical analysis. As outlined in the study design, our analysis was restricted to data from patients with follow-up at our institution only, and comparison with patients who underwent Fontan procedure with postoperative follow-up at other institutions was beyond the scope of this study. Lastly, confounding variables such as ventricular function and presence of AV valve regurgitation may have influenced the prevalence of arrhythmias in our population and were not fully evaluated in this analysis.
Disclosures The authors have no conflicts of interest to disclose. 1. Fontan F, Baudet E. Surgical repair of tricuspid atresia. Thorax 1971;26:240e248. 2. Sharratt GP, Johnson AM, Monro JL. Persistence and effects of sinus rhythm after Fontan procedure for tricuspid atresia. Br Heart J 1979;42: 74e80. 3. Ocello S, Salviato N, Marcelletti CF. Results of 100 consecutive extracardiac conduit Fontan operations. Pediatr Cardiol 2007;28: 433e437. 4. Brown JW, Ruzmetov M, Deschner BW, Rodefeld MD, Turrentine MW. Lateral tunnel Fontan in the current era: is it still a good option? Ann Thorac Surg 2010;89:556e563. 5. Vouhé PR. Fontan completion: intracardiac tunnel or extracardiac conduit? Thorac Cardiovasc Surg 2001;49:27e29. 6. Stephenson EA, Lu M, Berul CI, Etheridge SP, Idriss SF, Margossian R, Reed JH, Prakash A, Sleeper LA, Vetter VL, Blaufox AD, Pediatric Heart Network Investigators. Arrhythmias in a contemporary Fontan cohort. J Am Coll Cardiol 2010;56:890e896. 7. Anderson P, Sleeper L, Mahony L, Colan S, Atz A, Breitbart R, Gerson W, Gallagher D, Geva T, Margossian R. Contemporary outcomes after the Fontan procedure: a Pediatric Heart Network multicenter study. J Am Coll Cardiol 2008;52:85e98. 8. Blaufox AD, Sleeper LA, Bradley DJ, Breitbart RE, Hordof A, Kanter RJ, Stephenson EA, Stylianou M, Vetter VL, Saul JP. Functional status, heart rate, and rhythm abnormalities in 521 Fontan patients 6 to 18 years of age. J Thorac Cardiovasc Surg 2008;136:100e107 (e1). 9. Nurnberg J, Ovroutski S, Aleximeskishvili V, Ewert P, Hetzer R, Lange P. New onset arrhythmias after the extracardiac conduit Fontan operation compared with the intraatrial lateral tunnel procedure: early and midterm results. Ann Thorac Surg 2004;78:1979e1988.
10. Dilawar M, Bradley SM, Saul JP, Stroud MR, Balaji S. Sinus node dysfunction after intraatrial lateral tunnel and extracardiac conduit Fontan procedures. Pediatr Cardiol 2003;24:284e288. 11. Azakie A, McCrindle BW, Van Arsdell G, Benson LN, Coles J, Hamilton R, Freedom RM, Williams WG. Extracardiac conduit versus lateral tunnel cavopulmonary connections at a single institution: impact on outcomes. J Thorac Cardiovasc Surg 2001;122:1219e1228. 12. Fiore A, Turrentine M, Rodefeld M, Vijay P, Schwartz T, Virgo K, Fischer L, Brown J. Fontan operation: a comparison of lateral tunnel with extracardiac conduit. Ann Thorac Surg 2007;83:622e630. 13. Van Son J, Mohr F, Hambsch J. Conversion of atriopulmonary or lateral atrial tunnel cavopulmonary anastomosis to extracardiac conduit Fontan modification. Eur J Cardiothorac Surg 1999;15:150e158. 14. Marcelletti C, Corno A, Giannico S, Marino B. Inferior vena cavapulmonary artery extracardiac conduit. A new form of right heart bypass. J Thorac Cardiovasc Surg 1990;100:228e232. 15. Rodefeld MD, Bromberg BI, Schuessler RB, Boineau JP, Cox JL, Huddleston CB. Atrial flutter after lateral tunnel construction in the modified Fontan operation: a canine model. J Thorac Cardiovasc Surg 1996;111:514e526. 16. Lee JR, Kwak J, Kim KC, Min SK, Kim W, Kim YJ, Rho JR. Comparison of lateral tunnel and extracardiac conduit Fontan procedure. Interact Cardiovasc Thorac Surg 2007;6:328e330. 17. Hasaniya NW, Razzouk AJ, Mulla NF, Larsen RL, Bailey LL. In situ pericardial extracardiac lateral tunnel Fontan operation: fifteen-year experience. J Thorac Cardiovasc Surg 2010;140:1076e1083. 18. Kwak JG, Kim W-H, Lee JR, Kim YJ. Surgical therapy of arrhythmias in single-ventricle patients undergoing Fontan or Fontan conversion. J Card Surg 2009;24:738e741. 19. Tweddell JS, Nersesian M, Mussatto KA, Nugent M, Simpson P, Mitchell ME, Ghanayem NS, Pelech AN, Marla R, Hoffman GM. Fontan palliation in the modern era: factors impacting mortality and morbidity. Ann Thorac Surg 2009;88:1291e1299. 20. Hirsch JC, Goldberg C, Bove EL, Salehian S, Lee T, Ohye R, Devaney EJ. Fontan operation in the current era. Ann Surg 2008;126:52e60. 21. Nakano T, Kado H, Tachibana T, Hinokiyama K, Shiose A, Kajimoto M, Ando Y. Excellent midterm outcome of extracardiac conduit total cavopulmonary connection: results of 126 cases. Ann Thorac Surg 2007;84:1619e1626. 22. Giannico S, Hammad F, Amodeo A, Michielon G, Drago F, Turchetta A, Di Donato R, Sanders SP. Clinical outcome of 193 extracardiac Fontan patients. J Am Coll Cardiol 2006;47:2065e2073. 23. Tsao S, Deal BJ, Backer CL, Ward K, Franklin WH, Mavroudis C. Device management of arrhythmias after Fontan conversion. J Thorac Cardiovasc Surg 2009;138:937e940. 24. Mavroudis C, Deal BJ, Backer CL, Steward RD, Franklin WH, Tsao S, Ward KM, Defreitas RA. 111 Fontan conversions with arrhythmia surgery: surgical lessons and outcomes. Ann Thorac Surg 2007:1457e1466.