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a Department of Cardiac Surgery Children's Hospital Boston, Harvard Medical School, Boston, Massachusetts
b Department of Cardiology, Children's Hospital Boston, Harvard Medical School, Boston, Massachusetts
Accepted for publication March 26, 2009.
* Address correspondence to Dr del Nido, Department of Cardiac Surgery, Children's Hospital Boston, 300 Longwood Ave, Boston, MA 02115 (Email: pedro.delnido{at}cardio.chboston.org).
Presented at the Forty-fifth Annual Meeting of The Society of Thoracic Surgeons, San Francisco, CA, Jan 26–28, 2009.
| PEDIATRIC CARDIAC SURGERY:
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| Abstract |
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Methods: The medical records of all Fontan patients evaluated for heart transplantation at a single institution from 1994 to 2008 were retrospectively reviewed. Demographic, hemodynamic, and laboratory data were collected. Patients were stratified into an IVF or PVF group by echocardiographic criteria. Descriptive statistics and Kaplan-Meier analysis were used for hypothesis testing.
Results: Thirty-four Fontan patients were evaluated for heart transplantation. According to echo description of systolic function, 18 were categorized as IVF and 16 as PVF. The IVF group had a significantly lower cardiac index and venous oxygen saturation, and significantly higher systemic vascular resistance vs the PVF group (p < 0.05). PLE or PB was present in 13 PVF patients and none in the IVF group. Twenty patients underwent transplantation, with similar rates amongst the IVF and PVF groups. Within 1 year from evaluation, 2 IVG patients and 7 PVF patients had died (p = 0.052).
Conclusions: Failing Fontan patients with PVF have decreased overall survival independent of whether they underwent transplantation. This trend indicates a need to improve the management and timing for transplantation amongst this population.
In 1968 Fontan and Baudet introduced total right heart bypass achieved with atriopulmonary connection in a patient with tricuspid atresia—the first Fontan [1, 2]. Since that time, palliation of functional single ventricles has undergone many revisions to improve survival and decrease long-term morbidity [3, 4].
Although survival has improved markedly since the first palliative operations, these patients are still at increased risk of late morbidity and death [5]. Late complications of Fontan palliation include progressive ventricular dysfunction, atrioventricular (AV) valve regurgitation, progressive cyanosis, thromboembolism, protein-losing enteropathy (PLE), plastic bronchitis, atrial tachyarrhythmias, and Fontan pathway obstruction [6–9]. If medical, surgical, and catheter-based interventions are unable to improve symptoms, cardiac transplantation may provide the only therapeutic treatment for many of these patients [5, 9–11].
The factors contributing to heart failure or failing Fontan physiology in patients with a Fontan repair remain poorly defined. Identifying which factors may contribute to death or increased risk of failure requiring medical or surgical intervention is difficult because Fontan patients are a heterogeneous group that differ in underlying anatomic malformation, type of Fontan operation, age at Fontan operation, and eras in which operations were performed. Understanding these factors will aid in the management decisions for these complex patients.
Amongst the failing Fontan patients, systolic ventricular dysfunction is a major indication for heart transplantation [12]. Other patients, however, have relatively preserved systolic ventricular function but present with complications of failed Fontan physiology, such refractory ascites, pleural effusions, PLE, and plastic bronchitis [8, 12, 13]. Because these conditions persist in the setting of relatively normal cardiac output, heart transplantation may not have an immediate effect on the course of the disease. Furthermore, the long-term consequences of malnutrition, immunosuppression, and pulmonary complications associated with PLE and plastic bronchitis may increase the risks of heart transplantation in these patients. Because of these findings we hypothesized that patients with failed Fontan physiology and preserved ventricular function are at increased risk of dying, both before and after cardiac transplantation.
| Patients and Methods |
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Patients were identified by search of the Children's Hospital cardiovascular program database for patients who had undergone a Fontan operation at any institution but were evaluated for heart transplantation at Children's Hospital Boston between January 1, 1994, and January 1, 2008. The criterion for referring the patient for heart transplant evaluation was physician-dependant. All patients had been discharged from the hospital, were more than 60 days from the time of last Fontan operation, and had at least 6 months of follow-up from the time of evaluation. The study excluded patients who had a previous Fontan takedown to a superior caval-pulmonary anastomosis (bidirectional Glenn).
A detailed retrospective review was conducted of all medical records. Demographic data, including inpatient, clinic, and operative notes, were collected. Laboratory, functional, and hemodynamic data, including cardiac catheterization and echocardiographic data, were analyzed. Patient survival and transplant status were also recorded. Because many patients underwent subsequent functional and hemodynamic testing after transplantation evaluation, only data available at the time of transplant evaluation were collected for analysis. The type of Fontan was classified as right atrium to pulmonary artery anastomosis, a lateral tunnel, or extracardiac conduit.
AV valve anatomy and systemic ventricular morphology were categorized according to previously defined nomenclature on the basis of preoperative studies and surgical findings. Cardiac function was evaluated by 2-dimensional (2D) echocardiography and cardiac catheterization. Ventricular dysfunction was defined qualitatively as none, mild, moderate, or severe by a clinician not involved in the care of the patient. AV valve regurgitation was graded by echocardiography as mild, moderate, or severe based on the width of the Doppler color flow jet and the extent of the regurgitation into the atrium.
Study Cohorts
The patient cohort was divided into two groups based on 2D echocardiographic findings of ventricular systolic function. Patients who were diagnosed with moderate to severe ventricular dysfunction were assigned to the impaired ventricular function (IVF) group. Patients with mild or no ventricular dysfunction were assigned to the preserved ventricular function (PVF) group. The diagnosis of PLE required the following criteria: hypoalbuminemia (
3.0 mg/dL) for 3 months or longer in the absence of liver or renal disease and accompanying ascites, pleural effusions, edema, diarrhea, or abdominal pain for 3 months or longer [7, 14]. Plastic bronchitis was diagnosed by recurrent formation of branching bronchial casts of the tracheobronchial tree [8, 15].
Statistical Analysis
The unpaired t test was used to compare the continuous variables of age at evaluation, time since Fontan operation, and pretransplantation laboratory values and hemodynamics, including cardiac index, systemic oxygen saturation, Fontan pathway pressures, pulmonary vascular resistance, and systemic vascular resistance. Continuous variables were expressed as mean ± standard deviation, unless otherwise stated. Categoric variables, including gender, anatomic classification, left vs right ventricle dominance, ventricular dysfunction, AV valve regurgitation, PLE, plastic bronchitis, arrhythmias, and use of pacemaker, were summarized as proportion ± standard deviation and compared using the Pearson
2 test and, where appropriate, the Fisher exact test. The Bonferroni correction was used to account for multiple comparisons.
To estimate proportional survival after evaluation for transplantation, a Kaplan-Meier analysis was performed in which patients with PVF were compared with individuals with IVF. Survival was further compared between patients who had and had not undergone transplantation to estimate the overall outcome in both groups, including death after transplantation. Statistical significance was inferred at a 2-sided value of p < 0.05. The statistical analyses were computed with STATA 10.1 software (StataCorp, College Station, TX).
| Results |
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Overall, there were 7 deaths (43.8%) in the PVF group compared with 2 deaths (12.5%) in the IVF group (p = 0.052) during a mean follow-up of 55.2 ± 50 months (Table 3). Overall survival determined by Kaplan-Meier analysis (Fig 2) demonstrated patients with PVF with failing Fontan physiology had significantly worse midterm survival than patients with IVF. All deaths occurred within 1 year after the transplant evaluation, demonstrating a 1-year actuarial survival of 88.9% in the IVF group and 56.2% in the PVF group (p = 0.042).
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| Comment |
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Because PLE and plastic bronchitis were only found in the PVF group, it is tempting to impugn these two conditions as likely contributors. PLE is a devastating complication of Fontan physiology, with 50% mortality within 5 years after diagnosis [13, 16]. Multiple treatment modalities exist that likely reflect the paucity of definitive management principles based on a clear understanding of its cause [17]. Bernstein and colleagues [9] reported that PLE symptoms improved in 100% of patients who survived the initial period after transplantation, making a compelling argument for use of transplantation as a final treatment modality for refractory PLE [9]. Others have also documented an improvement in PLE after transplantation [18]. However, a recent review of long-term survival in patients with Fontan operations found PLE was an increased risk factor for death [7]. We found 33% of patients with PLE died: 2 before transplantation and 1 after.
In our study, 5 patients evaluated for heart transplantation were diagnosed with plastic bronchitis, with 3 deaths overall—2 after transplantation—during the follow-up period. Plastic bronchitis is becoming an increasingly recognized complication of congenital heart disease and particularly Fontan patients. Little is known about the cause of this difficult condition, and multiple therapies have been advanced without a clear consensus on the best management [15, 19, 20]. Furthermore, there are few data examining its role in Fontan failure or contribution to death after transplantation. We are limited by the small sample size; however, the results are concerning and point to the need for further study into the natural history of plastic bronchitis, including possible resolution after heart transplantation.
Three patients with PVF lacked the diagnosis of plastic bronchitis or PLE but had significant complications of pleural effusions, edema, and refractory ascites. These patients did not meet the stringent criteria for diagnosis of PLE in this study but could represent a spectrum of disease with PLE as the extreme manifestation [13]. The validity of grouping these patients is yet to be proven, although PLE and plastic bronchitis may share a similar cause [12, 21, 22].
IVF is a well-recognized indication for transplantation [12, 18]. In our study, 47% of patients were classified as having IVF by echocardiography and confirmed by catheterization, consistent with other reported rates of ventricular dysfunction [12]. Prior studies have suggested that progressive ventricular dysfunction is more common with the right ventricle [23, 24]. The morphologic right ventricle was the systemic ventricle in approximate two thirds of all patients in our study, with equal distribution in both the PVF and IVF groups. By log-rank test, a systemic right ventricle was not significantly associated with decreased survival.
All deaths within our study occurred within 1 year from the time of referral for transplantation, indicating that these patients are very sick at the time of evaluation. Survivors from the early period had equivalent midterm survival, indicating the increased risk of dying for those with PVF and failed Fontan physiology is in the early time period. Earlier referral of these patients may limit the negative consequences of the noncardiac complications of failed Fontan physiology such as PLE and plastic bronchitis, which could contribute to the increased mortality rate.
Our study has several limitations. First, the small sample size in each subgroup may limit detection of statistically significant differences. In addition, the study is limited by its retrospective nature. In particular at our large institution, the criteria for referral for cardiac transplantation evaluation are not standardized. This may contribute to the differences in outcome between the two groups, because one group may have been referred later.
In addition, certain eligible patients may have been excluded because of practitioner bias. Possible considerations include those who are thought to be too sick or too high risk for transplantation, or those whose families are not interested in transplantation as a therapeutic option and therefore referral was not made. More standardized criteria for evaluation are needed in late Fontan patients before we can definitively answer those who benefit most or are at greatest risk during heart transplantation.
Finally, the study is limited by the use of echocardiographic estimates of systolic function in single-ventricle patients and the difficulty in estimating the contribution of diastolic function to the pathology.
As increasing numbers of patients are palliated with Fontan operations, the number of children, adolescents, and young adults requiring late rescue therapy with heart transplantation will increase [11]. The sparse availability of hearts for transplantation and the associated morbidities with immunosuppression make it imperative that it is used appropriately. Therefore, much benefit would be derived from identifying those patients with failing Fontan physiology who might benefit from other modes of therapy and optimizing the timing of transplantation to exact the greatest benefit from such a scarce resource. Further study of diastolic dysfunction after the Fontan procedure may further clarify high-risk patients. In addition, developing ventricular support devices that may bridge patients more successfully are needed. It may be possible to better prepare the Fontan pulmonary circulation over months with pulsatile flow to better select patients for improved transplant outcomes.
In conclusion, patients referred for transplant evaluation with failing Fontan circulation have two different modes of presentation and can be categorized on the basis of their ventricular systolic function. This method of categorization identifies a group at higher risk that also presents with sequelae of failed Fontan physiology including PLE, plastic bronchitis, refractory ascites, and edema. This high-risk group has a greater than threefold risk of death within 1 year compared with the group that presents with poor ventricular function. Earlier referral for transplantation or alternative medical or surgical interventions should be considered for the high-risk group.
| DISCUSSION |
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DR GRIFFITHS: The cause of death did not differ between the two groups. There were 3 posttransplant deaths total, all in the preserved function group. Two of those patients had plastic bronchitis and one had PLE. The cause of death was categorized as cardiac failure in 2 patients and multisystem failure in 1 patient. We did not follow the patients after transplantation for resolution of symptoms.
DR CARL L. BACKER (Chicago, IL): That was a very nice analysis. I have two questions. I think our experience with transplanting the patient with a failed Fontan is that one of the hardest things to do is to say "No" to the potential recipient. Typically, this is a patient that you have been caring for in your program for many years. The mortality that we have had in our series has been the very sick patient that finally gets referred for transplantation and then you just can't say "No." The question I have relates to that. It looks to me like you said "No" quite a bit, because 40% of the patients that came for evaluation you declined to list. What happened to those patients?
DR GRIFFITHS: In the impaired ventricular function group, 14 patients were listed, and 4 were not listed—3 were considered too well and 1 was considered too sick. And all of those patients survived. Of the 14 listed, 11 were transplanted, all of those survived. In the nontransplanted group, 2 were considered too sick and subsequently died, and 1 is awaiting transplantation. In the preserved function group, 6 were not listed—4 were considered too sick and subsequently died.
DR BACKER: How long did it take them to die?
DR GRIFFITHS: All deaths occurred within the first year. The mean time to death was 102 days, with a range from 6 to 252 days.
DR BACKER: The second thing that came out of our analysis was that the combination of a failed Fontan and renal failure was really a bad combination and that predicted a mortality in our series of 66%. Did you have any patients that had—because renal failure frequently goes along with a failed Fontan—did you have patients with renal failure and what happened in that group?
DR GRIFFITHS: We didn't have any with overt renal failure. The mean creatinine was 0.7 mg/dL and did not differ between the two groups. We didn't look at creatinine clearance, which is probably a better marker to get an indication of their renal function. Creatinine didn't fall out as a risk factor for death in the cohort.
DR EMRE BELLI (Le Plessis-Robinson, France): I have a comment and a question. Our experience is totally different. Probably we transplant very early the PLE or bronchitis patients and too late in failing Fontan patients who are having big problems postoperatively, notably renal failure. My question, did you consider or try surgical or percutaneous fenestration before listing for transplant this group of patients with PLE or plastic bronchitis?
DR GRIFFITHS: I am sorry. I don't have that information as to what the algorithm was in managing these patients. That was part of the difficulty is figuring out what to do with these patients with PLE and plastic bronchitis. I think it is easier when a patient has ventricular dysfunction and they are starting to fail. You have a better idea of when to refer them for a transplant. With these patients with PLE or plastic bronchitis, when are they sick enough that they need transplantation? At what point do we need to be sending these to transplant before they get too sick? The fact that all these died within the first year means that we were looking at a very sick population.
DR FRANK PIGULA (Boston, MA): In terms of trying to get at that question, as you know, there have been very conflicting results about relieving or fenestrating a Fontan in those circumstances, although that has been tried in many of these patients. Some have gone to the cath lab for fenestration and stenting, while others have gone to the operating room. The results have been unpredictable.
And the way I think about these data that he has presented is that there is almost two different disease processes. In the first, the failure is in the myocardium and in the heart, and in the second is a failure in the in the body. And I think we are very good at picking up systolic failure in the myocardium. I don't think we are very good at understanding when you reach a tipping point in the failure of the body to accept that physiology. And I think that is the striking thing, to me, about the data that he has presented.
That one slide that you showed back earlier where there was almost a clear-cut demarcation between the 2 groups. In patients with failing systolic function, there was no plastic bronchitis or PLE, while in patients with preserved systolic function, and a third to a half of these patients had this.
DR ANTHONY AZAKIE (San Francisco, CA): Does that refer to systolic and diastolic function?
DR GRIFFITHS: This is systolic function. This is echo data.
DR AZAKIE: So "preserved function" can include diastolic dysfunction, right?
DR GRIFFITHS: Correct. But by echo and cardiac catheterization these patients had good cardiac systolic function.
DR JOHN LAMBERTI (San Diego, CA): The fact that everybody is still here even though it is the last paper suggests that this topic is very important and of great interest to all of us. Can you go to the next slide? In Jack Rychik's unified theory of PLE, the cardiac index is low. In your cases, the cardiac index is preserved in the PLE patients. This finding contradicts the idea that all PLE patients have impaired cardiac output. Overall, it is a very confusing picture, at least in my mind.
Speaking anecdotally, we have had some patients with PLE that responded very well to creation of a fenestration in the cath lab. When their sats go up, they have more PLE; and when they get their fenestration dilated, they are a little bluer and they feel better. So fenestration is useful in some patients.
DR BELLI: I will just add an experience. We had a 15-year-old patient, who previously developed pulmonary AV [arteriovenous] fistula, after kind of a Kawashima connection. We tunneled first the hepatic veins to the systemic venous chamber, then she developed PLE and we did a redo with direct connection using an extracardiac conduit. She was postoperatively okay, but she restarted PLE and that stopped, surprisingly, with medical treatment by Viagra (sildenafil). We fixed her PLE and she is okay now.
| Acknowledgments |
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