Reversal of protein-losing enteropathy in a child with Fontan circulation is correlated with central venous pressure after heart transplantation

Transplantation of the failing Fontan

Half a century has passed since the original Fontan palliation. In the interim, surgical and medical advancements have allowed more single ventricle patients to reach Fontan and long-term survival for Fontan patients to improve significantly. However, the risk for Fontan failure and need for heart transplantation remains. In this article we discuss mechanisms of Fontan failure, risk factors and special considerations for Fontan patients in both medical and surgical management around heart transplantation and provide an updated review of survival for Fontan patients after heart transplantation.

Characterization of Flow Efficiency, Pulsatility, and Respiratory Variability in Different Types of Fontan Circuits Using Quantitative Parameters

PURPOSE

Details on the hemodynamic differences among Fontan operations remain unclear according to respiratory and cardiac cycles. This study was undertaken to investigate hemodynamic characteristics in different types of Fontan circulation by quantification of blood flow with the combined influence of cardiac and respiratory cycles.

MATERIALS AND METHODS

Thirty-five patients [10 atriopulmonary connections (APC), 13 lateral tunnels (LT), and 12 extracardiac conduits (ECC)] were evaluated, and parameters were measured in the superior vena cava, inferior vena cava (IVC), hepatic vein (HV), baffles, conduits, and left and right pulmonary artery. Pulsatility index (PIx), respiratory variability index (RVI), net antegrade flow integral (NAFI), and inspiratory/expiratory blood flow (IQ/EQ) were measured by intravascular Doppler echocardiography.

RESULTS

The PIx between APC and total cavopulmonary connection (TCPC; LT and ECC) showed significant differences at all interrogation points regardless of respiratory cycles. The PIxs of HVs and IVCs in APC significantly increased, compared with that in LT and ECC, and the RVI between APC and TCPC showed significant differences at all interrogation points (p<0.05). The NAFI and IQ/EQ between APC and TCPC showed significant differences at some interrogation points (p<0.05).

CONCLUSION

Patients with different types of Fontan circulation show different hemodynamic characteristics in various areas of the Fontan tract, which may lead to different risks causing long-term complications. We believe the novel parameters developed in this study may be used to determine flow characteristics and may serve as a clinical basis of management in patients after Fontan operations.

Heart Transplantation in Children after a Fontan Procedure: Better than People Think

Previous studies have reported that children with a prior Fontan procedure have decreased survival after heart transplantation. We examined 273 primary pediatric heart transplants. Since 1988, 33 (12.1%) of 273 children <18 years old undergoing primary heart transplantation had a Fontan procedure 3.7 ± 4.3 years before transplantation. Compared with 240 (87.9%) non-Fontan primary transplants, the Fontan patients were older (8.8 ± 5.2 vs 6.6 ± 5.9 years; P = .023), but were similar in presensitization and pre-transplant clinical status. More Fontan patients had prior operations (100% vs 51.7%; P < .0001) and needed pulmonary artery reconstruction (100% vs 21.7%; P < .0001). Thirteen (39%) had protein-losing enteropathy. Donor ischemic times (213 ± 73 vs 177 ± 57 minutes; P = .0013) and cardiopulmonary bypass times (199 ± 86 vs 125 ± 53 minutes; P < .0001) were greater in the Fontan group, as were durations of ventilator support (4.4 ± 6.0 vs 2.5 ± 4.3 days; P = .035) and hospital stay (18.6 ± 16.1 vs 14.7 ± 13.1 days; P = NS). The Fontan group had one 30-day mortality. One-year actuarial survival (84.8% vs 86.9%, Fontan vs non-Fontan) and 5-year actuarial survival (70.8% vs 70.3%, Fontan vs non-Fontan) were similar, as was rejection incidence at 1 year (2.0 ± 2.0 vs 1.7 ± 1.9 episodes/patient; P = .3972). Five Fontan patients (18.5%) required retransplantation 4.9 ± 3.6 years post-transplant, compared with 22 non-Fontan patients (9.2%) retransplanted 5.2 ± 3.4 years post-transplant. Contrary to prior reports, we did not identify any early or mid-term disadvantage for children undergoing heart transplantation after a previous Fontan procedure, despite more complex transplant operations. We contend that carefully selected children with a failing Fontan circulation can do as well as other children with heart transplantation.

Treatment of children with protein - losing enteropathy after fontan and other complex congenital heart disease procedures in condition with limited human and technical resources

BACKGROUND

Protein-losing enteropathy (PLE) is a disorder characterized by abnormal and often profound enteric protein loss. It's relatively uncommon complication of Fontan and other complex congenital heart disease (CCHD) procedures. Because of the complexity and rarity of this disease process, the pathogenesis and pathophysiology of protein-losing enteropathy remain poorly understood, and attempts at treatment seldom yield long-term success.

AIM OF PRESENTATION

is to describe single centre experience in diagnosis, evaluation, management and treatment of children with protein-losing enteropathy after Fontan and other CCHD procedures in the current era and in centre with limited human and technical resources, follows with a comprehensive review of protein-losing enteropathy publications, and concludes with suggestions for prevention and treatment.

MATERIAL AND METHODOLOGY

Retrospectively we analyzed patients with CCHD and protein-losing enteropathy in our institution, starting from January 2000 to December 2012. The including criteria were age between two and 17 years, to have a complex congenital heart disease and available complete documentation of cardiac surgery under cardiopulmonary bypass.

RESULTS

Of all patients we evaluated 18 cases with protein-losing enteropathy, aged 6 to 19 years (mean 14±9); there were three children who had undergone screening procedure for D-transposition, one Tetralogy of Fallot, and remaining 14 patients had undergone Fontan procedures; (anatomic diagnosis are: six with tricuspid atresia, seven with d-transposition, double outlet right ventricle and pulmonary atresia and two with hypoplastic left heart syndrome). The diagnosis of protein-losing enteropathy was made at median age of 5.6 years, ranging from 13 months to 15 years. Diagnosis was made using alpha 1-antitrypsin as a gold marker in stool. By physical examination in 14 patients edema was found, in three ascites, and six patients had pleural effusion. Laboratory findings at the time of diagnosis are: abnormal enteric protein loss was documented at the time of diagnosis in all 18 patients. At the time of diagnosis all patients receiving some form of anticoagulation, 17 patients receiving other medication: 17 - diuretics and ACE inhibitors, 12 digoxin, 9 antiarrhytmics. Cross-sectional echocardiography was performed for all patients and different abnormalities were registered. In 14 patients also magnetic resonance was performed. Therapeutic approach was based on the non-specific medication (diet, diuretics, digoxin, ACE inhibitors, and anticoagulants), heparin and corticosteroids therapy. Long-term response to this type of therapy was registered in three patients. Nine patients underwent treatment with heparin and corticosteroids and no one experienced long term benefit. Despite of needs for catheter therapy or surgical intervention in our study, in the absent of technical and human resources now any one had underwent those procedures. Six patients has been transferred abroad and in five of them surgical intervention was perform.

CONCLUSION

Protein-losing enteropathy remains a devastating complication of Fontan procedure and despite in advantages in surgical and medical therapy there is no evidence that protein-losing enteropathy is less common in the current area.

Simulation of the Fontan circulation during rest and exercise

The Fontan palliation was introduced as surgical repair method for tricuspid atresia, creating a univentricular serial circulation. However, it is used as treatment for other life threatening complex congenital heart diseases as well. The variation of underlying pathologies treated with this palliation makes optimization difficult. To assist the optimization process, we adjusted a lumped parameter computational model of the biventricular circulation (CircAdapt) and evaluated the univentricular circulation. The model simulates beat-to-beat dynamics of the two cardiac chambers, the valves, and the systemic and pulmonary circulations. The univentricular circulation in rest and exercise was simulated. Exercise resulted in increased stroke volume, heart rate, pulse pressure, and stressed blood volume. Central venous pressure rose as a result of the constant pulmonary resistance, reducing systemic pressure drop. Reduced systemic pressure drop implies either reduction of systemic flow or further decrease of systemic resistance. Based on our simulation results, we conclude that exercise capacity in Fontan patients is limited due to increase of central venous pressure and the impossibility to reduce systemic resistance further, restricting systemic flow.

Protein-losing enteropathy: integrating a new disease paradigm into recommendations for prevention and treatment

Protein-losing enteropathy is a relatively uncommon complication of Fontan procedures for palliation of complex congenital cardiac disease. However, the relative infrequency of protein-losing enteropathy belies the tremendous medical, psychosocial and financial burdens it places upon afflicted patients, their families and the healthcare system that supports them. Unfortunately, because of the complexity and rarity of this disease process, the pathogenesis and pathophysiology of protein-losing enteropathy remain poorly understood, and attempts at treatment seldom yield long-term success. The most comprehensive analyses of protein-losing enteropathy in this patient population are now over a decade old, and re-evaluation of the prevalence and progress in treatment of this disease is needed. This report describes a single institution experience with the evaluation, management, and treatment of protein-losing enteropathy in patients with congenital cardiac disease in the current era, follows with a comprehensive review of protein-losing enteropathy, focused upon what is known and not known about the pathophysiology of protein-losing enteropathy in this patient population, and concludes with suggestions for prevention and treatment.

The Fontan pathway: What's down the road?

The Fontan circulation results from routing of the systemic venous blood to the pulmonary circulation without a hydraulic source of a ventricle. Although a hypertrophied right atrium was thought to be essential for this circulation, the current form of the operation has neither the right atrium nor any valves in the venous circulation that is connected to the pulmonary arteries directly. Modifications in the operative model was one of the early steps in improving outcome. Use of fenestration, staging of Fontan completion and better perioperative management have led to a significant drop in mortality rates in the current era. Despite this, there is late attrition of patients with complications such as arrhythmias, ventricular dysfunction, and unusual clinical syndromes of protein-losing enteropathy (PLE) and plastic bronchitis. Management of failing Fontan includes a detailed hemodynamic and imaging assessment to treat any correctable lesions such as obstruction within the Fontan circuit, early control of arrhythmia and maintenance of sinus rhythm, symptomatic treatment for PLE and plastic bronchitis, manipulation of systemic and pulmonary vascular resistance, and Fontan conversion of less favorable atriopulmonary connection to extra-cardiac total cavopulmonary connection with arrythmia surgery. Cardiac transplantation remains the only successful definitive palliation in the failing Fontan patients.

Protein-losing enteropathy after Fontan operation

Protein-losing enteropathy (PLE) is a poorly understood and enigmatic disease process affecting patients with single ventricle after Fontan operation. In those afflicted, PLE after Fontan operation results in significant morbidity and mortality. The pathophysiology of the disease is unknown; however, a proposed mechanism incorporates a combination of phenomena including: (1) altered hemodynamics, specifically low cardiac output; (2) increased mesenteric vascular resistance; (3) systemic inflammation; and (4) altered enterocyte basal membrane glycosaminoglycan make-up. A paradigm for the clinical management of PLE after Fontan operation is proposed.

Results of transcatheter Fontan fenestration to treat protein losing enteropathy

Transcatheter fenestration to create an interatrial communication has been used to treat patients with protein losing enteropathy (PLE) after Fontan operation. No systematic data have been reported assessing the results of this procedure. Our institutional database was queried to identify patients after Fontan operation who had transcatheter fenestration to treat PLE. Clinical notes, laboratory data, echocardiograms, and cardiac catheterization data were reviewed. From 1995 to 2005, 16 transcatheter fenestration procedures were performed in seven patients. Median age at fenestration was 18 years (range 13-41 years). Median duration of follow-up was 3.6 years (range 0.2-10.4 years). Techniques for fenestration included blade/balloon septostomy, stent placement, Amplatzer-fenestrated ASD device, and balloon dilation of previous stent. Size of the fenestration created was 5.2 +/- 1.1 mm. Systemic venous pressure remained unchanged after fenestration. Cardiac index increased significantly. Reduction of ascites and edema was noted after 9 of the 16 procedures. Ten of 16 (63%) of fenestrations spontaneously occluded. Three patients are free of ascites although recurrence of PLE occurred in all. One patient with a patent fenestration continues to have ascites. Two patients had Fontan takedown. One patient had conversion to a fenestrated extracardiac conduit Fontan and died postoperatively. The results of transcatheter Fontan fenestration are often disappointing. Maintaining fenestration patency is difficult. Even after "successful" fenestration, resolution of PLE may be incomplete and recurrences have occurred in all. Early consideration should be given to Fontan takedown or cardiac transplant in severely symptomatic patients with PLE who do not respond to fenestration. Transcatheter fenestration may be a bridge to a definitive procedure.

Outcome of listing for cardiac transplantation for failed Fontan: a multi-institutional study

BACKGROUND

The Fontan procedure is a successful palliation for children with single-ventricle physiology; however, many will eventually require heart transplantation. The purpose of this study was to determine risk factors for death awaiting transplantation and to examine results after transplantation in Fontan patients.

METHODS AND RESULTS

A retrospective, multi-institutional review was performed of 97 Fontan patients <18 years of age listed at 17 Pediatric Heart Transplant Study centers from 1993 to 2001. Mean age at listing was 9.7 years (0.5 to 17.9 years); 25% were <4 years old; 53% were United Network for Organ Sharing status 1; 18% required ventilator support. Pretransplantation survival was 78% at 6 months and 74% at 12 months and was similar to 243 children with other congenital heart disease (CHD) and 747 children without congenital heart disease (No-CHD), who were also awaiting transplantation. Patients who were younger, status 1, had shorter interval since Fontan, or were on a ventilator were more likely to die while waiting. At 6 months, the probability of receiving a transplant was similar for status 1 and 2 (65% versus 68%); however, the probability of death was higher for status 1 (22% versus 5%). Seventy patients underwent transplantation. Survival was 76% at 1 year, 70% at 3 years, and 68% at 5 years, slightly less than CHD and No-CHD patients. Causes of death included infection (30%), graft failure (17%), rejection (13%), sudden death (13%), and graft coronary artery disease (9%). Protein-losing enteropathy (present in 34 patients) resolved in all who survived >30 days after transplantation.

CONCLUSIONS

Heart transplantation is an effective therapy for pediatric patients with a failed Fontan. Although early posttransplantation survival is slightly lower than other patients with CHD, long-term results are encouraging, and protein-losing enteropathy can be expected to resolve.

Applied glycoproteomics—approaches to study genetic-environmental collisions causing protein-losing enteropathy

Protein-losing enteropathy (PLE), the loss of plasma proteins through the intestine, is a life-threatening symptom associated with seemingly unrelated conditions including Crohn's disease, congenital disorder of glycosylation, or Fontan surgery to correct univentricular hearts. Emerging commonalities between these and other disorders led us to hypothesize that PLE develops when genetic insufficiencies collide with simultaneous or sequential environmental insults. Most intriguing is the loss of heparan sulfate (HS) proteoglycans (HSPG) specifically from the basolateral surface of intestinal epithelial cells only during PLE episodes suggesting a direct link to protein leakage. Reasons for HSPG loss are unknown, but genetic insufficiencies affecting HSPG biosynthesis, trafficking, or degradation may be involved. Here, we describe cell-based assays we devised to identify key players contributing to protein leakage. Results from these assays confirm that HS loss directly causes protein leakage, but more importantly, it amplifies the effects of other factors, e.g., cytokines and increased pressure. Thus, HS loss appears to play a central role for PLE. To transfer our in vitro results back to the in vivo situation, we established methods to assess enteric protein leakage in mice and present several genetically deficient strains mimicking intestinal HS loss observed in PLE patients. Preliminary results indicate that mice with haploinsufficient genes involved in HS biosynthesis or HSPG trafficking develop intestinal protein leakage upon additional environmental stress. Our goal is to model PLE in vitro and in vivo to unravel the pathomechanisms underlying PLE, identify patients at risk, and provide them with a safe and effective therapy.

Heparan Sulfate Plays a Central Role in a Dynamic in Vitro Model of Protein-losing Enteropathy

Protein-losing enteropathy (PLE), the loss of plasma proteins through the intestine, is a symptom in ostensibly unrelated diseases. Emerging commonalities indicate that genetic insufficiencies predispose for PLE and environmental insults, e.g. viral infections and inflammation, trigger PLE onset. The specific loss of heparan sulfate (HS) from the basolateral surface of intestinal epithelial cells only during episodes of PLE suggests a possible mechanistic link. In the first tissue culture model of PLE using a monolayer of intestinal epithelial HT29 cells, we proved that HS loss directly causes protein leakage and amplifies the effects of the proinflammatory cytokine tumor necrosis factor alpha (TNFalpha). Here, we extend our in vitro model to assess the individual and combined effects of HS loss, interferon gamma (IFNgamma), TNFalpha, and increased pressure, and find that HS plays a central role in the patho-mechanisms underlying PLE. Increased pressure, mimicking venous hypertension seen in post-Fontan PLE patients, substantially increased protein leakage, but HS loss, IFNgamma, or TNFalpha alone had only minor effects. However, IFNgamma up-regulated TNFR1 expression and amplified TNFalpha-induced protein leakage. IFNgamma and TNFalpha compromised the integrity of the HT29 monolayer and made it more susceptible to increased pressure. HS loss itself compromises the integrity of the monolayer, amplifying the effects of pressure, but also amplifies the effects of both cytokines. In the absence of HS a combination of increased pressure, IFNgamma, and TNFalpha caused maximum protein leakage. Soluble heparin fully compensated for HS loss, providing a reasonable explanation for patient favorable response to heparin therapy.

Resolution of protein-losing enteropathy after radiofrequency perforation and subsequent stent implantation for relief of complete occlusion of a redirected left superior vena cava

The application of radiofrequency (RF) technologies in the treatment of congenital heart defects has provided a safe and effective alternative to conventional therapies in the restoration of vascular patency for a variety of arterial and venous occlusions. This report concerns an 8-year old girl that developed protein-losing enteropathy and elevated central venous pressure after occlusion of a surgically redirected anomalous draining left superior vena cava (SVC). Cardiac catheterization revealed complete obstruction of the anastomosis of the SVC into the coronary sinus. Transcatheter recanalization by RF perforation and subsequent stent implantation led to the restoration of upper venous blood flow and the resolution of her symptoms.

Heart transplantation in patients with previous Fontan operations

OBJECTIVE

The clinical features and outcomes of patients undergoing heart transplantation after a failed Fontan operation are still debated. The aim of this study was to retrospectively evaluate our experience in 14 patients undergoing heart transplantation after previous Fontan-type operations.

METHODS

From 1990 to 2002, 14 patients underwent heart transplantation in our institution after a previous Fontan procedure. The mean age at the time of the Fontan operation and at transplantation was 7.3 +/- 2.8 and 17.2 +/- 6.3 years, respectively. The indication for transplantation was protein-losing enteropathy in 7 patients, arrhythmia with ventricular dysfunction in 5 patients, and heart failure in 2 patients. All patients received basic immunosuppressive therapy with cyclosporine (INN: ciclosporin) and azathioprine without induction therapy or maintenance steroids.

RESULTS

Two hospital deaths occurred: one patient died on the fifth postoperative day of graft failure, and the second died on the 17th postoperative day after an acute neurologic event. Two patients died later, one 23 months after transplantation of acute rejection and the other after 90 months of chronic rejection and endocarditis. One patient underwent successful reintervention 2 years after heart transplantation for pulmonary vein obstruction. The 10 surviving patients are in New York Heart Association class I, with a mean follow-up of 64.5 +/- 42 months. One of them was delivered of a healthy baby 5 years after transplantation. Patients with protein-losing enteropathy reached a normal protein level within a mean of 10 months (range, 6-18 months) after transplantation. Four patients required a temporary administration (3-6 months) of oral steroid therapy for recurrent rejection episodes. Currently, 7 patients are taking cyclosporine, and 3 are taking cyclosporine and azathioprine. The actuarial survival at 1, 5, and 10 years was 86% +/- 9%, 77% +/- 12%, and 62% +/- 17%, respectively.

CONCLUSION

Heart transplantation is a good option for patients with a failing Fontan operation. We documented the reversibility of protein-losing enteropathy in all patients. No mortality caused by surgical complications was observed.

Protein-losing enteropathy after Fontan surgery: resolution after cardiac transplantation

Protein-losing enteropathy (PLE), defined as severe loss of serum protein into the intestine, occurs in 4% to 13% of patients after the Fontan procedure. We report a case of PLE reversal after heart transplantation in a 14-year-old boy with Fontan circulation who previously was treated unsuccessfully with medical therapy. The protein loss continued after heart transplantation. We administered total parenteral nutrition to rest the bowel. After 16 months, we observed a gradual decrease in protein loss. The patient is doing well 5 years after heart transplantation and had has a normal serum albumin level.