The Fontan immunophenotype and post-transplant outcomes in children: A multi-institutional study.

BACKGROUND: Patients after Fontan palliation represent a growing pediatric population requiring heart transplant (HTx) and often have lymphopenia (L) and/or hypogammaglobinemia that may be exacerbated by protein-losing enteropathy (PLE, P). The post-HTx effects of this altered immune phenotype are not well studied. METHODS: In this study of the Pediatric Heart Transplant Society Registry, 106 Fontan patients who underwent HTx between 2005 and 2018 were analyzed. The impact of lymphopenia and PLE on graft survival, infection, rejection, and malignancy was analyzed at 1 and 5 years post-HTx. RESULTS: The following combinations of lymphopenia and PLE were noted: +L+P, n = 37; +L-P, n = 23; -L+P, n = 10; and -L-P, n = 36. Graft survival between the groups was similar within the first year after transplant (+L+P: 86%, +L-P: 86%, -L+P: 87%, -L-P: 89%, p = .9). Freedom from first infection post-HTx was greatest among -L-P patients compared to patients with either PLE, lymphopenia, or both; with a 22.1% infection incidence in the -L-P group and 41.4% in all others. These patients had a significantly lower infection rate in the first year after HTx (+L+P: 1.03, +L-P: 1, -L+P: 1.3, -L-P: 0.3 infections/year, p < .001) and were similar to a non-single ventricle CHD control group (0.4 infections/year). Neither freedom from rejection nor freedom from malignancy 1 and 5 years post-HTx, differed among the groups. CONCLUSIONS: Fontan patients with altered immunophenotype, with lymphopenia and/or PLE, are at increased risk of infection post-HTx, although have similar early survival and freedom from rejection and malignancy. These data may encourage alternative immunosuppression strategies and enhanced monitoring for this growing subset of patients.

Pediatric heart transplant from an incompletely treated influenza A-positive donor.

There is a shortage of pediatric donor hearts for waitlisted children, and yet nearly 50% of organs offered are not transplanted. Donor quality is often cited as a reason for declining organs offered from donors infected with influenza, presumably due to concern about disease transmission at transplant leading to severe disease. We previously described an excellent outcome after heart transplant from a donor infected with influenza B that had been treated with a complete course of oseltamivir. In this report, we describe a similar outcome after transplantation of an organ from an influenza A-positive donor with symptomatic disease incompletely treated with oseltamivir. Due to the availability of effective antiviral treatment, we suggest that influenza A is also a manageable donor infection that need not preclude heart placement.

Trajectory of right ventricular indices is an early predictor of outcomes in hypoplastic left heart syndrome.

BACKGROUND: Children with hypoplastic left heart syndrome (HLHS) have risk for mortality and/or transplantation. Previous studies have associated right ventricular (RV) indices in a single echocardiogram with survival, but none have related serial measurements to outcomes. This study sought to determine whether the trajectory of RV indices in the first year of life was associated with transplant-free survival to stage 3 palliation (S3P). METHODS: HLHS patients at a single center who underwent stage 1 palliation (S1P) between 2000 and 2015 were reviewed. Echocardiographic indices of RV size and function were obtained before and following S1P and stage 2 palliation (S2P). The association between these indices and transplant-free survival to S3P was examined. RESULTS: There were 61 patients enrolled in the study with 51 undergoing S2P, 20 S3P, and 18 awaiting S3P. In the stage 1 perioperative period, indexed RV end-systolic area increased in patients who died or needed transplant following S2P, and changed little in those surviving to S3P (3.37 vs -0.04 cm2 /m2 , P = .017). Increased indexed RV end-systolic area was associated with worse transplant-free survival. (OR = 0.815, P = .042). In the interstage period, indexed RV end-diastolic area increased less in those surviving to S3P (3.6 vs 9.2, P = .03). CONCLUSION: Change in indexed RV end-systolic area through the stage 1 perioperative period was associated with transplant-free survival to S3P. Neither the prestage nor poststage 1 indexed RV end-systolic area was associated with transplant-free survival to S3P. Patients with death or transplant before S3P had a greater increase in indexed RV end-diastolic area during the interstage period. This suggests earlier serial changes in RV size which may provide prognostic information beyond RV indices in a single study.

Pediatric heart transplantation from an influenza B-positive donor.

As heart transplantation demand is increasing without subsequent growth of the donor pool, need for expansion of acceptance criteria is paramount, particularly when considering critically ill, highly sensitized patients. We present a case report of a pediatric heart transplant recipient of an organ refused by 197 prior potential recipients due to the donor being infected with influenza virus. We perform a literature review of recent solid organ transplant cases from influenza-positive donors and conclude that the donor pool may be expandable by allowing donors with treatable infections to be included.

Gain-of-function mutations in SMAD4 cause a distinctive repertoire of cardiovascular phenotypes in patients with Myhre syndrome.

Myhre syndrome is a rare, distinctive syndrome due to specific gain-of-function mutations in SMAD4. The characteristic phenotype includes short stature, dysmorphic facial features, hearing loss, laryngotracheal anomalies, arthropathy, radiographic defects, intellectual disability, and a more recently appreciated spectrum of cardiovascular defects with a striking fibroproliferative response to surgical intervention. We report four newly described patients with typical features of Myhre syndrome who had (i) a mildly narrow descending aorta and restrictive cardiomyopathy; (ii) recurrent pericardial and pleural effusions; (iii) a large persistent ductus arteriosus with juxtaductal aortic coarctation; and (iv) restrictive pericardial disease requiring pericardiectomy. Additional information is provided about a fifth previously reported patient with fatal pericardial disease. A literature review of the cardiovascular features of Myhre syndrome was performed on 54 total patients, all with a SMAD4 mutation. Seventy percent had a cardiovascular abnormality including congenital heart defects (63%), pericardial disease (17%), restrictive cardiomyopathy (9%), and systemic hypertension (15%). Pericarditis and restrictive cardiomyopathy are associated with high mortality (three patients each among 10 deaths); one patient with restrictive cardiomyopathy also had epicarditis. Cardiomyopathy and pericardial abnormalities distinguish Myhre syndrome from other disorders caused by mutations in the TGF-ß signaling cascade (Marfan, Loeys-Dietz, or Shprintzen-Goldberg syndromes). We hypothesize that the expanded spectrum of cardiovascular abnormalities relates to the ability of the SMAD4 protein to integrate diverse signaling pathways, including canonical TGF-ß, BMP, and Activin signaling. The co-occurrence of congenital and acquired phenotypes demonstrates that the gene product of SMAD4 is required for both developmental and postnatal cardiovascular homeostasis. © 2016 Wiley Periodicals, Inc.

Bortezomib use in a pediatric cardiac transplant center.

Data are limited on the efficacy and safety of bortezomib for the treatment of AMR following OHT for pediatric acquired or CHD. Retrospective chart review identified patients who received bortezomib for acute (n = 3, within two wk of diagnosis) and chronic (n = 1, three months after diagnosis) AMR or as part of a desensitization regimen (n = 1). Bortezomib was associated with a 3-66% reduction in class I DSA and a 7-82% reduction in class II DSA. Two of the three acute AMR cases resolved by the first follow-up biopsy. Two patients with AMR resolution are currently well. One patient developed a second episode of AMR, which was unresponsive to bortezomib therapy and required retransplantation for progressive coronary allograft vasculopathy. One patient died shortly after the third cycle from multi-organ failure. The desensitization patient showed transient HLA reduction with two cycles, but died five months after transplant from sepsis. Complications included infection (3/5), peripheral neuropathy (2/5), AKI (2/5), and thrombocytopenia (3/5). Adverse events appear more common in critically ill patients. Bortezomib therapy resulted in variable DSA reduction and AMR resolution in AMR in OHT secondary to pediatric acquired or CHD.

Predictors of cardiac allograft vasculopathy in pediatric heart transplant recipients.

CAV remains a leading cause of late graft loss and mortality among survivors of pediatric heart transplantation. We sought to define the incidence of CAV and identify its predictors in pediatric heart transplant recipients. The OPTN/UNOS database was analyzed for pediatric recipients who underwent heart transplant between 1987 and 2011. The primary end-point is time from heart transplantation to development of CAV (CAV-free survival). To identify predictors of CAV-free survival, demographic and transplant data were analyzed by the Kaplan-Meier survival method and Cox proportional hazards regression. Of 5211 pediatric heart transplant recipients with at least one-yr follow-up, the incidence of CAV at five, 10, and 15 yr was 13%, 25%, and 54%, respectively. Multivariate analysis found that risk of CAV was associated with the following variables: Recipient age 1-4 yr (HR 1.25), 5-9 yr (1.45), 10-18 yr (1.83), donor age >18 yr (1.34), re-transplantation (2.14), recipient black race (1.55), and donor cigarette use (1.54). Older recipient and donor age, recipient black race, donor cigarette use, and re-transplantation were highly associated with shorter CAV-free survival.

Orthotopic heart transplant: a therapeutic option for unresectable cardiac fibroma in infants.

Primary cardiac tumors are rare lesions in childhood, with the two most common being rhabdomyoma and fibroma. We report two infants who successfully underwent orthotopic heart transplant for massive interventricular septal cardiac fibromas. For unresectable infantile cardiac fibroma, orthotopic heart transplant may be considered a therapeutic option.

Recurrent protein-losing enteropathy and tricuspid valve insufficiency in a transplanted heart: a causal relationship?

This case report describes a toddler who developed a protein-losing enteropathy (PLE) 4 years after orthotopic heart transplantation (OHT). He was born with a hypoplastic left heart syndrome for which he underwent a successful Norwood procedure, a Hemi-Fontan palliation, and a Fontan palliation at 18 months of age. Fifteen months following the Fontan operation, he developed a PLE and Fontan failure requiring OHT. Four years after OHT, he developed a severe tricuspid regurgitation and a PLE. His PLE improved after tricuspid valve replacement. It is now 2 years since his tricuspid valve replacement and he remains clinically free of ascites and peripheral edema with a normal serum albumin level. His prosthetic tricuspid valve is functioning normally.

Effect of hypothermia on doxorubicin-induced cardiac myoblast signaling and cell death.

BACKGROUND: Anthracyclines (AC) are useful chemotherapeutic agents whose principal limitation is cardiac toxicity, which may progress to heart failure, transplantation or even death. We have shown that this toxicity involves oxidative stress-induced activation of the DNA damage pathway. Hypothermia has been shown to be protective against other diseases involving oxidative stress but has not been studied in models of AC toxicity. METHODS: In the current experiments, H9C2 cardiac myoblasts were treated with varying concentrations of the AC doxorubicin (DOX) during normothermia (37°C) or mild hypothermia (35°C). Total cell death was assayed using trypan blue exclusion and apoptosis by terminal deoxynucleotidyl transferase-mediated deoxyuridine-biotin nick end labeling (TUNEL) staining. Oxidative stress was assayed using the fluorescent indicator 2'7'-dichlorofluorescein diacetate. DNA damage pathway activation was assayed by immunostaining for H2AX and p53. Mitochondrial membrane potential was assayed by JC-1 staining. RESULTS: At all concentrations of DOX examined (1, 2.5 and 5 µM), hypothermia reduced oxidative stress, activation of H2AX and p53, loss of mitochondrial membrane potential and total and apoptotic cell death (P=.001-.03 for each observation). CONCLUSIONS: The reduction of oxidative stress-induced activation of the DNA damage pathway and consequent cell death by mild hypothermia supports a possible protective role to reduce the clinical impact of DOX-induced cardiac toxicity. Such an approach may allow expanded use of these effective chemotherapeutic agents to increase cancer cure rates.

Perioperative renal failure in pediatric heart transplant recipients: outcome and risk factors.

PRF is encountered in 10-13% of adult heart transplants. Only one study of a single center's experience with PRF has been reported in pediatric patients. This study examines the effect of PRF on pediatric heart transplant outcome using the UNOS database. A total of 3598 patients met inclusion criteria, of whom 254 (7%) had PRF. The PRF group comprised 31 recipients requiring PRE and 223 recipients requiring POST. Compared with No-PRF patients, PRE patients had similar survival rate and POST patients had decreased survival rate at 30 days, one, five, and 10-yr post-transplant (p < 0.001). PRF patients also had significantly lower graft survival at one, five, and 10 yr (p < 0.001). Risk factors for developing PRF included ECMO, ventilator, and inotropic support at listing and CHD as the listing diagnosis. PRF increased the duration of hospital stay and the incidence of chronic severe renal dysfunction. PRF that requires POST (whether or not it began pretransplant) has a significant negative impact on pediatric heart transplant outcome. Specific characteristics identify patients at particular high risk of developing PRF.

Low donor-to-recipient weight ratio does not negatively impact survival of pediatric heart transplant patients.

A major limitation to success in pediatric heart transplantation is donor organ shortage. While the use of allografts from donors larger than the recipient is accepted, the use of undersized donor grafts is generally discouraged. Using the UNOS database, we wanted to evaluate whether using smaller donor hearts affects the short- and long-term survival of pediatric heart transplant patients. A retrospective analysis of data entered into the UNOS database from April 1994 to May 2008 was performed. Pediatric heart transplant recipients (ages 0-18 yr) with DRWR <2.0 were identified and divided into two groups: Low-DRWR (<0.8) and Ideal-DRWR (0.8-2.0). Patients' demographics, pretransplant diagnoses, age at transplantation, severity of pretransplant condition, and rate of complications prior to hospital discharge after transplantation were noted. Fisher's exact, chi-square, and Wilcoxon rank sum tests were used to compare patients' baseline characteristics. Kaplan-Meier curves and Cox proportional hazard regression were used to compare patients' survival and to identify independent risk factors for outcomes. There were 3048 patients (204 with Low- and 2844 with Ideal-DRWR). The Low-ratio group patients were older (8.3 vs. 6.9 yr; p = 0.001), there was a slight male predominance in the Low-DRWR group (p = 0.055). The Low-DRWR group had longer transplant wait time than the Ideal-DRWR group (97 vs. 85 days; p = 0.04). The groups did not differ in race, primary diagnoses, severity of pretransplant condition (medical urgency status, need for ventilation, inotropic support, ECMO, nitric oxide, or dialysis, the PVR for those with bi-ventricular anatomy), or post-transplant complications (length of stay, need for inotropic support, dialysis, and rate of infections). The Low-DRWR patients had less episodes of acute rejection during the first-post-transplant month. Infants with DRWR 0.5-0.59 had lower 30-day survival rate (p = 0.045). There was no difference in short- and long-term survival between the patients with DRWR 0.6-0.79 and DRWR 0.8-2.0. Use of smaller allografts (DRWR 0.6-0.8) has no negative impact on the short- and long-term survival of pediatric heart transplant patients.

Identification and cloning of a new protein that binds the 3(') untranslated region of alpha-striated tropomyosin.

The 3' untranslated region of muscle tropomyosin (TM UTR) induces muscle differentiation when transcribed in primary fibroblasts. This sequence binds protein in extracts from cell types that differentiate upon TM UTR transcription. To identify the protein(s) bound by the TM UTR, an avian embryo fibroblast library was induced to express protein in solution and extracts from these pools were screened with electromobility shift assays using a TM UTR RNA probe. Positive pools were progressively fractionated until a pool containing a single positive clone was obtained. The TM UTR-binding protein (UBP) clone thus isolated contains 751 nt, 618 of which represent a single open reading frame. UBP is related to a human autoantigen, Sjogren's syndrome antigen B (SSB) beginning with the start of the UBP open reading frame. This homology is to the 5' end of SSB in a region containing an RNA-binding motif of 70 amino acids. The deduced amino acid sequence of UBP predicts phosphorylation sites for protein kinase C, casein kinase 2, and cAMP-dependent protein kinase and asparginine glycosylation sites. The observed size of UBP by UV cross-linking with a TM UTR probe is of the same size as the protein bound in fibroblast extract. UBP is expressed in primary fibroblasts, but not in fibroblast or myogenic cell lines, suggesting that its expression is restricted. The full-length UBP mRNA is approximately 3 kB, suggesting a long 5' untranslated region. Transient transfection of cultured cells with UBP directs production of a protein that binds the TM UTR, confirming that these sequences interact in vivo. These observations suggest that we have identified a novel protein that binds to the TM UTR in vitro and in vivo. Determining the function of this protein will facilitate determining the mechanism by which the TM UTR induces differentiation.