Practice variation in the diagnosis of acute rejection among pediatric heart transplant centers: An analysis of the pediatric heart transplant society (PHTS) registry.

BACKGROUND: Freedom from rejection in pediatric heart transplant recipients is highly variable across centers. This study aimed to assess the center variation in methods used to diagnose rejection in the first-year post-transplant and determine the impact of this variation on patient outcomes. METHODS: The PHTS registry was queried for all rejection episodes in the first-year post-transplant (2010-2019). The primary method for rejection diagnosis was determined for each event as surveillance biopsy, echo diagnosis, or clinical. The percentage of first-year rejection events diagnosed by surveillance biopsy was used to approximate the surveillance strategy across centers. Methods of rejection diagnosis were described and patient outcomes were assessed based on surveillance biopsy utilization among centers. RESULTS: A total of 3985 patients from 56 centers were included. Of this group, 873 (22%) developed rejection within the first-year post-transplant. Surveillance biopsy was the most common method of rejection diagnosis (71.7%), but practices were highly variable across centers. The majority (73.6%) of first rejection events occurred within 3-months of transplantation. Diagnosis modality in the first-year was not independently associated with freedom from rejection, freedom from rejection with hemodynamic compromise, or overall graft survival. CONCLUSIONS: Rejection in the first-year after pediatric heart transplant occurs in 22% of patients and most commonly in the first 3 months post-transplant. Significant variation exists across centers in the methods used to diagnose rejection in pediatric heart transplant recipients, however, these variable strategies are not independently associated with freedom from rejection, rejection with hemodynamic compromise, or overall graft survival.

Bronchiolitis obliterans is not the primary cause of death in pediatric living donor lobar lung transplant recipients.

BACKGROUND: Obliterative bronchiolitis (OB) is the chief cause of mortality in cadaveric lung transplant patients (CL). But, is OB the primary cause of mortality for living donor lobar recipients? To answer this question, we reviewed the causes of mortality in our pediatric patients who underwent living donor lobar lung transplantation (LD) and compared them with our pediatric patients who received whole cadaveric lungs (CL). METHODS: Data collected included demographics, transplant type, hospital days, immunosuppression regimen, and cause of death. Statistical analysis was done using Fisher's Exact test and Student's t-test (mean +/- SD). RESULTS: From May 1993 to December 1999, 53 patients underwent lung transplantation (21 males, 32 females; mean age 12.4 +/- 5.4 years). Twenty-nine patients had LD procedures (12 males, 17 females; mean age 14.4 +/- 3.6 years) and 24 patients had CL surgery (9 males, 15 females; p = .78 [not significant]; mean age 9.8 +/- 6.3 years; p =.001). All patients received triple immunosuppression without induction. During the study period, 9 LD (6 males, 3 females; mean age 15.7 +/- 5.0 years) and 14 CL (3 males, 11 females; mean age 11.3 +/- 6.9 years) patients died. There was no significant difference between patients in the LD and CL groups who died with regard to gender (p = .08), age at the time of death (p = .12), mortality rate (p = .06), number of hospital days (p = .09), immunosuppressive medications (p > .08), incidence of non-specific graft failure (p = .26), or incidence of infection (p = .18). However, there was a significant difference in the incidence of OB between LD and CL recipients (p = .002). CONCLUSIONS: OB was not found to be the chief cause of mortality in pediatric LD recipients. We speculate that prevention of infections, possibly by a modest reduction in immunosuppressive therapy and aggressive antimicrobial therapy, may improve long-term survival in pediatric living donor lobar lung transplant recipients.

Cardiac and great vessel injuries in children after blunt trauma: an institutional review.

PURPOSE: The purpose of this study was to review the incidence of cardiac and great vessel injury after blunt trauma in children. METHOD: A retrospective review of 2,744 patients with injuries from blunt mechanisms was performed. RESULTS: Eleven patients sustained cardiac injury. Four patients had clinically evident cardiac contusions. All recovered. Four patients who died from central nervous system injury were found to have cardiac contusions at autopsy. None had clinical evidence of contusion before demise. One patient had a traumatic ventricular septal defect (VSD) that required operative repair. Autopsy findings showed a VSD in another patient, and a third patient was found to have a ventricular septal aneurysm that was treated medically. Two patients had great vessel injuries. One patient had a contained disruption of the superior vena cava that was managed nonoperatively. Another patient had a midthoracic periaortic hematoma without intimal disruption found at autopsy. One patient had cardiac and great vessel injuries. Discrete aneurysms of 2 coronary artery branches and the pulmonary outflow tract were identified by cardiac catheterization. This patient was treated nonoperatively. CONCLUSIONS: Cardiac and great vessel injury after blunt trauma are uncommon in children. Cardiac contusion was the most common injury encountered but had minimal clinical significance. Noncontusion cardiac injury is rare. No patient with aortic transection was identified.

DNA-liposome versus adenoviral mediated gene transfer of transforming growth factor beta1 in vascularized cardiac allografts: differential sensitivity of CD4+ and CD8+ T cells to transforming growth factor beta1.

We have developed a model of transforming growth factor (TGF)beta1 gene transfer into mouse vascularized cardiac allografts to study the use of gene transfer as an immunosuppressive therapy in transplantation. Donor hearts were perfused with either DNA-liposome complexes or adenoviral vectors that encode the active form of human TGFbeta1. DNA-liposome mediated transfection prolonged allograft survival in approximately two-thirds of transplant recipients, while adenoviral delivery of TGFbeta1 was not protective. Protective TGFbeta1 gene transfer was associated with reduced Th1 responses and an inhibition of the alloantibody isotype switch. The protective effects of TGFbeta1 gene transfer were overridden by exogenous interleukin-12 administration. Interestingly, alloreactive CD4+ and CD8+ cells exhibited distinct sensitivities to TGFbeta1 gene transfer: CD4+ Th1 function was abrogated by this modality, although CD8+ Th1 function was not. Transient depletion of recipient CD8+ cells markedly prolonged the survival of grafts transfected with either DNA-liposome complexes or adenoviral vectors. Transgene expression persisted for at least 60 days, and Th1 responses were not detectable until CD8+ T cells repopulated the periphery. However, long-term transfected allografts appeared to exhibit exacerbated fibrosis and neointimal development. These manifestations of chronic rejection were absent in long-term transfected isografts, suggesting that long-term expression of active TGFbeta1 alone is not sufficient to induce fibrosis of the grafts. Collectively, these data illustrate the utility of immunosuppressive gene therapy as a treatment for transplantation when combined with additional conditioning regimens. Further, they illustrate that alloreactive CD4+ and CD8+ cells may be differentially influenced by cytokine manipulation strategies.