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Ann Thorac Surg 2005;80:1445-1452
© 2005 The Society of Thoracic Surgeons
a Michael E. DeBakey Department of Surgery, Division of Congenital Heart Surgery, Texas Heart Institute, Baylor College of Medicine, Houston, Texas
b Department of Pediatrics, Division of Pediatric Cardiology, Texas Heart Institute, Baylor College of Medicine, Houston, Texas
c Section of Biostatistics and Epidemiology, Texas Heart Institute, Baylor College of Medicine, Houston, Texas
Accepted for publication March 28, 2005.
* Address reprint requests to Dr Morales, Division of Congenital Heart Surgery, Texas Children's Hospital, 6621 Fannin St, WT-19345H, Houston, TX 77030 (Email: dlmorale{at}texaschildrenshospital.org).
Presented at the Forty-first Annual Meeting of The Society of Thoracic Surgeons, Tampa, FL, Jan 24–26, 2005.
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Abstract |
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METHODS: Thirty-five Fontan revisions were performed (Jun 1997 to Dec 2004): 19 ECC (54%) and 16 LT. Preoperative variables were similar: New York Heart Association (NYHA) IV (LT = 4 vs ECC = 2, p = not significant [NS]), preoperative arrhythmias (LT = 13 vs ECC = 16, p = NS) and systemic right ventricle (LT = 4 vs ECC = 2, p = NS). Twenty-eight patients (80%) underwent a modified maze procedure (LT = 12 vs ECC = 16, p = NS) and 29 (83%) had pacemaker placement (LT = 11 vs ECC = 18, p < 0.05).
RESULTS: There were no hospital deaths and no arrhythmias at hospital discharge. There were no differences in mean duration of intubation (LT 0.6 vs ECC 0.9 days, p = NS), inotropic support (LT 1.5 vs ECC 2.1 days, p = NS), intensive care unit stay (LT 2.6 vs ECC 3.5 days, p = NS), hospital stay (LT 8.8 vs ECC 9.7 days, p = NS), or episodes of acute postoperative arrhythmias (LT = 2 vs ECC = 4, p = NS). On intermediate follow-up (29 ± 22 months), the overall cohort had 94% survival, 97% of survivors in NYHA class I/II, 91% freedom from late arrhythmias requiring medication, and no patient required cardiac transplantation. Follow-up revealed no differences in NYHA I/II (LT = 14 vs ECC = 18, p = NS), mortality (LT = 2 vs ECC = 0, p = NS), or late arrhythmia (LT = 4 vs ECC = 4, p = NS).
CONCLUSIONS: Both the LT and ECC revisions provide symptomatic benefit for a failing Fontan connection and have equivalent early and intermediate results including arrhythmia recurrence.
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Introduction |
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Over the past two decades, Fontan circulations, especially the earlier configurations (ie, atrio-pulmonary), have begun to fail secondary to a combination of conduit obstruction, arrhythmias, and systemic ventricular failure [2]. Until recently, medical therapy and transplant were the only options for failing Fontan patients, often resulting in disappointing outcomes. Experience and success with Fontan revision, as an alternative management strategy, has been increasing since the first reports in the late 1990s [3–13]. Most published data on Fontan revisions have involved conversion to the ECC configuration [5, 8, 9, 11]. This preference perhaps stems from data that suggest an advantage for the ECC over the LT configuration for primary TCPC, mostly related to postoperative arrhythmias [14]. In 1998, Mavroudis and colleagues [13] began to demonstrate that postoperative arrhythmia control was an essential part to the Fontan revision strategy. Therefore, many believe that using the ECC configuration is not only technically more straightforward, but may be superior in decreasing postoperative arrhythmias. A comparison between the ECC and LT configurations in Fontan revisions has never been completed. The utilization of the ECC and LT configurations in Fontan revisions is approximately equal at our institution, which presents the unique opportunity to study potential differences.
The purpose of this study is to review our overall experience with the Fontan revision strategy and to compare the results of the LT and the ECC connections in Fontan revisions with special emphasis on the incidence of acute and late postoperative arrhythmias.
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Material and Methods |
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Operative Technique
Mode of Fontan revision was chosen solely on surgeon preference. Much of this decision was based on whether there were any widely patent components of the existing Fontan configuration that could be incorporated into a lateral tunnel, and on the quality of right atrial tissue (eg, amount of scarring and thickness of the atrial wall). Direct aortobicaval cannulation was accomplished centrally in every case. Following the initiation of cardiopulmonary bypass and cardioplegic arrest, an extensive oblique right atriotomy was performed. The prior Fontan connection was taken down, if not incorporated into a LT. A wide-open atrial septectomy was assured, and an intraoperative modified maze was performed as described by Mavroudis and colleagues [5], but intraoperative mapping was not utilized. We used a combination of cryo (presently preferred energy source), radiofrequency, and surgical lesions to complete the modified maze procedure. Right atrial debulking was selectively employed at the time of atriotomy closure, based on the size of the native right atrium. The LT Fontan was constructed by leaving the coronary sinus to drain on the pulmonary venous side of the baffle and by incorporating the atriopulmonary connection from the primary Fontan if widely patent. The ECC connection was constructed with a 22 or 24 mm standard wall Gortex graft while the heart was beating and during rewarming. After separating from cardiopulmonary bypass, steroid-eluting epicardial leads were utilized for most pacemaker insertions. We employed routine intraoperative transesophageal echocardiography before repair to confirm the suspected anatomy and after to assure an unobstructed Fontan circuit and to assess cardiac function. All patients receive aspirin therapy postoperatively, regardless of LT or ECC configuration.
Statistical Analysis
Data were recorded on a Microsoft Excel spreadsheet (Microsoft, Redmond, WA) and transferred to the SAS statistical package (SAS Institute, Inc, Cary, NC) for analysis. All numerical data are listed as the mean ± standard deviation unless otherwise specified. Comparison of preoperative demographic and catheterization data, operative data, and outcome variables were performed for patients undergoing LT versus ECC Fontan revision. Associations between categorical data were tested and reported with Fisher's exact test (two-sided) or 
2. Associations involving continuous data were tested and reported with Student's t test (pooled, equal variance) or Wilcoxon rank sums test (two-sided). A p value of < 0.05 was required for statistical significance.
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Results |
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Ninety-seven percent of survivors are in NYHA functional class I or II. There were 2 late deaths, both in the LT group, for an overall mortality of 6%. One patient was admitted 11.3 months postrevision for work-up of severe cyanosis and died from a VF arrest 5 days after a cardiac catheterization demonstrated multiple intrapulmonary arteriovenous malformations. There was another late death at 7.4 months after Fontan revision in a 15-year-old boy readmitted for ascites and abdominal pain. Cardiac catheterization revealed a baffle thrombus resulting in elevated Fontan pressures. The child underwent balloon atrial septectomy but died of respiratory failure after a prolonged hospital course.
A late rhythm disturbance has been recorded for 8 patients (23%). One patient had atrial flutter responding to direct current cardioversion and atenolol with no further events. Five patients had IART; 3 are currently off medication with no further events, 1 remains controlled with sotalol, and one patient had IART with a brief episode of VT that required implantable cardioverter defibrillator (ICD) placement 34 months after revision with no further recurrences on amiodarone. Atrial tachycardia was detected in 2 patients, both of whom are not on medication and have not had recurrences. Seven of 33 survivors (21%) are currently on antiarrhythmic medication; the 3 patients listed above for late arrhythmias and 4 for acute postoperative arrhythmias. Of all the patients (14) who have had arrhythmias postrevision, 50% had brief episodes that have not reoccurred or required medicine, and no patient has had a second arrhythmia. All arrhythmias are controlled on no medication (7 patients) or one medication.
Failure of Fontan conversion was considered a death (early or late) or receiving an orthotopic heart transplant. As can be seen by the Kaplan-Meier curve (Fig 1), the freedom from Fontan failure was 93% at 1 year and at 3.5 years.
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Comment |
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Fontan conversion now offers these patients another and, for the majority, a preferred management strategy. Indications for conversion typically include an interrelated combination of increasing symptoms of heart failure, systemic ventricular failure, elements of anatomic obstruction, and refractory arrhythmias. As underscored by the recent literature on Fontan revision, avoiding arrhythmias and reestablishing atrioventricular synchrony has become a central element of the Fontan revision. Almost all recent series have included intraoperative ablative therapy and the routine practice of placing permanent pacemakers [5, 11]. This ensures a rate responsive, atrioventricular synchronized rhythm regardless of the incidence of sinus node dysfunction or recurrent atrial arrhythmias (10% to 30%) postoperatively [5, 11, 17]. Fontan conversion in some centers is now associated with a hospital mortality of 0% to 5%, almost uniform improvement in NYHA class and exercise endurance, and a greater than 80% freedom from late recurrence of arrhythmias [5, 11]. Our intermediate follow-up (29 ± 22 months) results overall (0% operative mortality, no arrhythmias at hospital discharge, 97% NYHA class I/II, 0 refractory arrhythmias, 89% freedom from late arrhythmias requiring medication, and 93% freedom from Fontan revision failure) are congruent with contemporary series.
The present forms of the Fontan operation include the LT or ECC. The ECC affords the surgeon the advantages of decreasing the suture load in the atrium (possible arrhythmogenic focus), excluding all atrial tissue so dilation is restricted and avoiding cardioplegic arrest (not realized in Fontan conversion) [18]. Advantages for the LT include growth potential and all of those associated with the avoidance of a conduit, particularly in the low pressure, right-sided circulation (ie, thrombosis, fixed size). Theoretically, these TCPCs will not have the same rate of Fontan failure as the earlier versions since they have better flow hydrodynamics [19, 20]. However, one must consider that the lack of failure thus far may simply be a matter of a shorter length of follow-up. Regardless, the LT and the ECC have been the configurations to which the failing Fontans have been converted. There is a strong inclination seen in the Fontan revision literature toward the ECC configuration [5, 8, 9, 11, 17]. This preference probably stems from the most recent data that suggest an advantage for the ECC over the LT configuration for primary TCPC, related principally to postoperative rhythm disturbance [21]. In a series of 107 primary Fontan connections, Azakie and colleagues [14] found the LT patients had a significantly higher incidence of postoperative sinus node dysfunction, supraventricular tachycardia, and need for temporary postoperative pacing than the ECC cohort. Furthermore, multivariate analysis identified the LT connection as an independent predictor of atrial arrhythmias in the acute postoperative and intermediate follow-up periods.
Despite these data, we were unable to show any outcome difference between the ECC and LT configurations in the Fontan revision of 35 patients. These groups were equivalently matched in all preoperative characteristics except age. The significance of this is unclear since the cohorts demonstrated no difference in weight, symptomatology (ie, NYHA class or arrhythmia status), or the preoperative hemodynamic data. Operative data demonstrated that these groups had similar procedures except that ECC creation required a longer cardiopulmonary bypass time. In several patients, construction of the lateral tunnel incorporated widely patent connections of the previous configuration, thus decreasing the number of anastomoses required and the number of connections that needed to be dismantled. This resulted in shorter cardiopulmonary bypass times that may explain this difference. The LT cohort also had fewer pacemakers placed, which is a result of there being a tendency toward using LT configurations in our earlier experience when we did not always place permanent pacemakers. However, since early 2001 all patients have undergone an intraoperative modified maze and pacemaker placement, which corresponds to the last 23 consecutive patients. There are no significant differences between the LT and ECC patients in the intensive care unit or hospital course end points such as length of stay, inotropic support, mechanical ventilation, or operative mortality (0 for both groups). Neither the incidence of acute nor late arrhythmias differed between the two configurations. More specifically, IART recurrence or late arrhythmias requiring chronic antiarrhythmia medication did not significantly differ. Most importantly, LT and ECC cohorts did not differ during intermediate follow-up in their functional results, number of orthotopic heart transplants, or late mortality.
More important than the choice of TCPC configuration is the choice of an appropriate candidate for Fontan conversion. Some purport a direct correlation between hemodynamic and symptomatic results of Fontan revision with the number of preoperative Fontan related issues (ie, baffle obstruction, arrhythmia, etc) [8, 9]. Patients with isolated decreased systemic ventricular function and/or class IV heart failure tend to benefit from Fontan conversion less dramatically and consistently, leading to death or their transition to orthotopic heart transplant more often and more rapidly [4–6, 8]. The largest series to date reported 60% of class IV patients required orthotopic heart transplant after Fontan conversion [5]. In our series, the only two failures of Fontan conversion were patients in NYHA class IV preoperatively (a 33% mortality for our class IV patients). Earlier Fontan revision, especially for atriopulmonary Fontan patients, seems to be critical in improving upon these results; as demonstrated by the more favorable outcomes in the literature with patients that have less systemic ventricular failure, less chronic nonconverted atrial arrhythmias, and less left-sided focused arrhythmias [5, 11]. At our institution, the timing of referral for Fontan conversion has changed over the past 7 years. We now assertively move toward Fontan revision in any Fontan patient who has any atrial arrhythmia that accompanies any clinical, physiologic, or anatomic findings consistent with Fontan failure or impending Fontan failure. In the last three years, almost all patients put forward for Fontan revision have had difficult to control arrhythmias as their primary diagnosis and have been in NYHA class I or II. Since the middle of 2002, no patient has progressed to NYHA class IV before undergoing Fontan revision.
There is a growing body of data to support the belief that Fontan conversion can be accomplished safely and with a high expectation for significant hemodynamic and symptomatic improvement. At intermediate follow-up, the choice of TCPC configuration (ECC or LT) used for Fontan conversion does not seem to affect these encouraging results. Whether the long-term result of Fontan revision will be as a destination therapy or as a bridge to transplant or permanent mechanical support is yet unknown, but present results advocate early Fontan conversion as an effective primary therapy for the failing Fontan patient.
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Discussion |
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You did not show how many patients you had with atrial fibrillation. It would be interesting to know how many patients were operated with atrial fibrillation and whether, in fact, you used a Maze-Cox III procedure for ablation.
In our experience, we've shown that patients who present relatively early have atrial reentry tachycardia. Waiting on those patients without an operation usually results in arrhythmia degeneration to atrial fibrillation. And in that group, at least in our hands, we have a higher incidence of acute renal failure, some of whom don't recover and require a kidney transplant. In our series of 80 patients one had a kidney transplant, another is awaiting one now. I wonder if you can share with us something about your patients who have had atrial fibrillation, and also how many patients postoperatively had renal failure. Judging by your mortality, I'm sure it's going to be low. Our experience is based on 80 patients, many of whom, about 35%, had atrial fibrillation. Those patients tend to be a little sicker and they give us the most trouble.
Apropos to your lateral tunnel versus extracardiac Fontan, of course we do an extracardiac Fontan for a number of reasons. One, I think it's easier to do; it's a simpler operation. The other has to do with the arrhythmia surgery. As you know, we're not removing hot spots, we're not removing an area in the atrium that's giving off these electrical charges. What we're doing is getting rid of areas of the atrium that have slow conduction. It's the areas of slow conduction that set up the atrial reentry tachycardia and eventual atrial fibrillation. So if one leaves extant suture lines as part of your reconstruction, one doesn't get rid of those areas. And so although I can't really duplicate your comparative study involving lateral tunnel versus extracardiac Fontan, which is beautifully done, it would seem to us that it would be better to remove all those anastomotic hookups and connections and convert them to an extracardiac Fontan.
This is a terrific paper. I would love to go on and on with it, because we share a lot of philosophies about how to do this, but I'd love to hear your answers to the questions.
DR MORALES: In terms of your first question, we fortunately have only had 3 patients who have had atrial fibrillation. All these patients presented to us before 2001, which is prior to your work showing the benefit of left-sided Mazes in these patients. So none of those patients received a left-sided Maze, and fortunately none of those patients have had a recurrence of any arrhythmia. I think though now, if we did have a patient who presented with atrial fibrillation, we would definitely do a left-sided Maze.
I think part of the reason we're not seeing those patients presently is because we are moving to doing patients earlier who are NYHA class I or II or who have any atrial arrhythmia, before they start to degenerate to atrial fibrillation.
We have also been very fortunate; we have had no patients who have had renal failure, if you define it as needing hemodialysis or any type of dialysis. There's been acute tubular necrosis (ATN), but no need for dialysis in our patients.
DR JOHN E. MAYER, JR (Boston, MA): I agree and would congratulate you and your colleagues in Houston on an excellent series.
These are procedure-related outcomes, and I think all of us know that there are other patients who aren't offered this procedure. So could you give us any information on if there were any patients who were excluded, offered other treatments, such as transplant or something, during the same time interval. And if so, what distinguished those patients from this group who underwent this procedure?
DR MORALES: Having reviewed our transplant data recently—we have done about 159 transplants—and looking back, we could only find 6 patients who actually had had previous Fontans who went on to transplant. I think most of those patients were before we were doing Fontan revisions. And I don't have any data on patients who were not offered Fontan revision or transplant. But I would assume if they did not get a revision, they would have had a transplant. But again, I didn't find many of those patients in our database.
DR CARL L. BACKER (Chicago, IL): Along those lines, did any of these patients have protein losing enteropathy (PLE) and what do you think about that as an indication for conversion versus heart transplantation?
DR MORALES: I think in our series there're only 2 patients that had PLE. One of those patients, the PLE resolved and that patient has gone back to work. The other patient has had recurrent episodes and admission for her PLE.
I do not think it's a contraindication, but I think your discussion with the patient should definitely be different in that those patients tend to do worse and I don't think you can expect the same type of outcomes. But I think they still are candidates for Fontan revision since even after Fontan revision transplant is still an option.
DR KIRK R. KANTER (Atlanta, GA): You said in your more recent cohort you routinely put a pacemaker in everybody. What percentage of the patients actually use the pacemaker or need the pacemaker?
DR MORALES: I'm sorry, I don't have that data. But I do believe that probably a fair amount do not.
DR KANTER: So you don't routinely ablate the AV (atrioventricular) node?
DR MORALES: We do not.
DR MAVROUDIS: I can add something to that. Our posture is that we pace everybody whether they need it or not. So if we atrially pace everybody, then they don't have an opportunity to put themselves into some kind of an arrhythmia by premature atrial beats.
I just rose just to mention that because it's an important part of a procedure. So we atrially pace everybody and sometimes it's atrioventricular, depending on the circumstances.
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  C. Mavroudis, B. J. Deal, C. L. Backer, R. D. Stewart, W. H. Franklin, S. Tsao, K. M. Ward, and R. A. DeFreitas 111 Fontan Conversions with Arrhythmia Surgery: Surgical Lessons and Outcomes Ann. Thorac. Surg., November 1, 2007; 84(5): 1457 - 1466. [Abstract] [Full Text] [PDF]
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 P. Khairy, N. Poirier, and L.-A. Mercier Univentricular Heart Circulation, February 13, 2007; 115(6): 800 - 812. [Abstract] [Full Text] [PDF]
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