Long-term results of triple-drug-based immunosuppression in nonneonatal pediatric heart transplant recipients

Pediatric heart transplantation-indications and outcomes in the current era

Pediatric heart transplantation (HTx) remains an important treatment option in the care of children with end-stage heart disease, whether it is secondary to cardiomyopathy or congenital heart disease (CHD). As surgical outcomes for CHD have improved, the indications for pediatric HTx have had to be dynamic, not only for children with CHD but also for the growing population of adults with CHD. As the field of pediatric HTx has evolved, the outcomes for children undergoing HTx have improved. This is undoubtedly due to the continued research efforts of both single-center studies, as well as research collaboratives such as the International Society for Heart and Lung Transplantation (ISHLT) and the Pediatric Heart Transplant Study (PHTS) group. Research collaboratives are increasingly important in pediatric HTx as single center studies for a limited patient population may not elicit strong enough evidence for practice evolution. Similarly, complications that limit the long term graft survival may occur in a minority of patients thus pooled experience is essential. This review focuses on the indications and outcomes for pediatric HTx, with a special emphasis on studies generated by these research collaboratives.

Pediatric heart transplantation-indications and outcomes in the current era

Pediatric heart transplantation (HTx) remains an important treatment option in the care of children with end-stage heart disease, whether it is secondary to cardiomyopathy or congenital heart disease (CHD). As surgical outcomes for CHD have improved, the indications for pediatric HTx have had to be dynamic, not only for children with CHD but also for the growing population of adults with CHD. As the field of pediatric HTx has evolved, the outcomes for children undergoing HTx have improved. This is undoubtedly due to the continued research efforts of both single-center studies, as well as research collaboratives such as the International Society for Heart and Lung Transplantation (ISHLT) and the Pediatric Heart Transplant Study (PHTS) group. Research collaboratives are increasingly important in pediatric HTx as single center studies for a limited patient population may not elicit strong enough evidence for practice evolution. Similarly, complications that limit the long term graft survival may occur in a minority of patients thus pooled experience is essential. This review focuses on the indications and outcomes for pediatric HTx, with a special emphasis on studies generated by these research collaboratives.

Postoperative care of the transplanted patient

The successful delivery of optimal peri-operative care to pediatric heart transplant recipients is a vital determinant of their overall outcomes. The practitioner caring for these patients must be familiar with and treat multiple simultaneous issues in a patient who may have been critically ill preoperatively. In addition to the complexities involved in treating any child following cardiac surgery, caretakers of newly transplanted patients encounter multiple transplant-specific issues. This chapter details peri-operative management strategies, frequently encountered early morbidities, initiation of immunosuppression including induction, and short-term outcomes.

Infectious, malignant, and autoimmune complications in pediatric heart transplant recipients

OBJECTIVE

To review clinical courses of pediatric heart transplant survivors after 5 years from transplantation for infections, lymphoproliferative, and autoimmune diseases.

STUDY DESIGN

A total of 71 patients were examined in 2 groups, infant recipients (underwent transplant <1 year of age, n = 38) and older recipients (underwent transplant >1 year, n = 33). All patients received comparable immunosuppression. Calculated occurrence rates were reported as means per 10 years of follow-up with SEs. Differences were examined by using Poisson regression.

RESULTS

Infant recipients had significantly higher (P < .001) occurrence rates of severe (mean, 2.04 +/- 0.5) and chronic infections (mean, 4.58 +/- 0.67) compared with older recipients (means, 0.37 +/- 0.19 and 1.87 +/- 0.70, respectively). Types of infections were similar to those in the general population with extremely rare opportunistic infections; however, they were more severe and resistant to treatment. Autoimmune disorders occurred at a frequency comparable with lymphoproliferative diseases and were observed in 7 of 38 infants (18%). Most common were autoimmune cytopenias.

CONCLUSIONS

Infant heart transplant recipients who survive in the long term have higher occurrence rates of infections compared with older recipients. Autoimmune disorders are a previously unrecognized morbidity in pediatric heart transplantation.

Immunosuppression and transplant vascular disease: benefits and adverse effects

Cardiac allograft vasculopathy (CAV) occurs within 5 years of transplantation surgery and represents the main cause of death in long-term heart transplant survivors. The detailed pathogenesis of CAV is unknown, but there are strong indications that immunologic mechanisms, which are regulated by nonimmunologic factors, are the major cause of this phenomenon. Cyclosporine A (CsA) is a frequently used immunosuppressive agent in transplant medicine to prevent rejection. The mechanism of action of CsA involves initial binding to cyclophilin to form a complex that then inhibits calcineurin (CN), leading to reduced interleukin (IL)-2 production as part of the signal transduction pathway for the activation of B-lymphocytes and T-lymphocytes. Based on this proposed mechanism, it was expected that CsA should be an effective strategy in attenuating the host immune response against transplanted allograft tissue; however, CsA has not changed the outcome of CAV. Several mechanisms have been suggested for the ineffectiveness of CsA in long-term prevention of CAV. For example, routine therapeutic doses of CsA may block CN incompletely (50%), whereas complete blockade requires doses that are not clinically tolerable. Another explanation is the possible activation of T-cell receptors directly (CN independent) by the immune response, which induces protein kinase C theta (PKCtheta) and leads to IL-2 production and immune rejection. Moreover, there may be a role for nonimmunologic mechanisms, such as complement, which cannot be controlled by CsA, or CsA may cause hypercholesterolemia or induce overexpression of transforming growth factor-beta (TGF-beta). This review also compares the effect of CsA with other immunosuppressants in allograft artery preservation and their clinical efficacy.

Transplantation immunology 2003: simplified approach

Transplantation has been performed clinically for four decades and has become the standard of care for end-stage organ failure. Understanding of the immunobiology of transplantation has made tremendous advances, but knowledge still lags behind the clinical use. As a result, nonspecific immunosuppression remains the standard therapy. This article presents an overview of current knowledge of the immunobiology of solid organ transplantation, with emphasis on T-cell activation (antigen presentation, CoS) and cellular allograft (transplantation) immunity. The molecular events of T-cell activation, with some emphasis on the sites of action of modern immunosuppression, are reviewed. A simplified approach to understanding the immunobiology and strategy of maintenance immunosuppression is discussed. Key early and late steps in T-cell activation and the sites of action of immunosuppressive agents are reviewed. The required cellular interactions for the alloresponse and the targets of biologic agents used in transplants are reviewed. Special considerations for the immunology in neonates, infants, and children as recipients are provided. Understanding the immunobiology of transplantation is key to making decisions about children with transplants, developing better protocols, and creating tolerance in the future.

Pediatric cardiac transplant: results using a steroid-free maintenance regimen

We report on survival, rejection, lymphoma and renal function following cardiac transplant using a steroid-free maintenance immunosuppressive regimen. We have performed 73 cardiac transplants in 71 children under 16 yr of age in the last 12 yr. There were eight perioperative and four late deaths giving actuarial survival of 88, 88, 85 and 70% at 1, 2, 5 and 10 yr, respectively. A total of 11 (15.3%) children had one episode of rejection (grade 3) in the first 6 months; one died and one was re-transplanted because of rejection. There was only one episode of late rejection (8 yr post-transplant) because of low drug levels in a patient with lymphoma and sepsis. This patient did not survive. Three other children (5.6%) also developed lymphoma and recovered but one died subsequently of graft failure. Four children have developed severe renal failure (glomerular filtration rate GFR <30 mL/min/m2). Two have not survived and one is expected to commence dialysis soon. The remainder have mild to moderate renal impairment. We report excellent survival and low rejection rates without use of long-term steroids. However the doses of cyclosporin used have had a significant effect on renal function in many cases.

Long-term outcomes after cardiac transplantation: an experience based on different eras of immunosuppressive therapy

BACKGROUND

Constantly changing practices in heart transplantation have improved posttransplant survival in patients with end-stage heart disease. The objective of this study was to evaluate long-term outcomes in different eras of immunosuppressive therapy after cardiac transplantation at a single center during a two-decade period.

METHODS

A retrospective review of 1,086 consecutive cardiac allograft recipients who underwent transplantation between 1977 to 1999 was performed. Patients were divided into four eras based on type of immunosuppressive therapy: era 1 = steroids, azathioprine (n = 26, February 1977 to March 1983), era II = steroids, cyclosporine (n = 43, April 1983 to April 1985), era III = cyclosporine, steroids, azathioprine (n = 752, April 1985 to December 1995), era IV = cyclosporine, steroids, mycophenolate mofetil (n = 315, January 1996 to October 1999).

RESULTS

The actuarial survival of the entire cohort of 1,086 patients undergoing cardiac transplantation was 79%, 66%, and 49% at 1, 5, and 10 years, respectively. There were significant trends in recipient age and gender distribution among the four eras with increasing proportion of older age (> 60 years) and female recipients in eras III and IV (p = 0.001 and 0.02). Early mortality and long-term survival improved significantly over all eras (p < 0.001). Rejection as a cause of death decreased over time (era I, 24%; era II, 21%; era III, 15%; era IV, 9%; p = 0.02), whereas the contribution of transplant coronary artery disease as a cause of death remained unchanged.

CONCLUSIONS

Cardiac transplantation provides satisfactory long-term survival for patients with end-stage heart failure. The improving outcomes in survival correlate with improved immunosuppressive therapy in each era. Although the reasons for improvement in survival over time are multifactorial, we believe that changes in immunosuppressive therapy have had a major impact on survival as evidenced by the decreasing number of deaths due to rejection.

Friedreich's ataxia presenting after cardiac transplantation

A 4 year old boy underwent cardiac transplantation because of cardiomyopathy with ischaemia. Following transplantation he developed neurological signs of Friedreich's ataxia and the diagnosis was confirmed with genetic testing. Cardiomyopathy is a rare presentation of Friedreich's ataxia and to our knowledge this is the first reported transplant operation for the cardiomyopathy associated with this condition.

Heart transplantation in children in foreign countries with reference to medical, transportation, and financial issues

Heart transplantation is increasingly becoming accepted worldwide as therapy for end-stage heart failure not only in adult patients but also in pediatric practice. The new law in Japan for organ transplantation from brain-dead patients was established on 16 October 1998, but there is no definite law or protocol for brain death in children under the age of 6 years and children less than 15 years of age cannot become donors. These facts make organ transplantation from the cadavers of neonates, infants and young children almost impossible in Japan, even though there are children who need heart or heart-lung transplantation. The present authors have to date transferred 8 patients to the USA or Germany for heart transplantation: 4 successfully underwent heart transplantation, but 4 died during the waiting period overseas. There are many things to consider; not only the medical problems involved in transportation, but also the financial issues when transferring patients to other countries. This report details the experience with the 8 cases that were transferred overseas for heart transplantation, and highlights the problems that need to be considered.

Immunosuppression for pediatric cardiac transplantation in the modern era

With the advent of the T cell activation inhibitors such as cyclosporine, heart transplant success rates for pediatric patients have improved to the point that the initially restricted ages and indications have expanded considerably. Currently the half-life (50% still alive) for children transplanted in the early 1980s is approximately 12-14 years. Decades-long survival seems likely. Components and functions of the immune system are naïve and change during postnatal development. Maturation occurs not only in the first years of life, but well through adolescence and even into adult life. These age-dependent changes within the immune system greatly complicate any attempt to assess immune implications for the use of immunosuppression in children. Since the introduction of cyclosporine, immunosuppression regimens have been virtually unchanged through the 1990s. Recently, there have been significant new immune pharmacological agents which are now commercially available, or still in investigational stages of development. The new maintenance immunosuppressive drugs are either inhibitors of de novo synthesis of nucleotides (purines or pyrimidines), or are immunophilin-binding drugs that inhibit signal transduction in lymphocytes. The newer inhibitors of de novo nucleotide synthesis include mycophenolate mofetil, mizoribine, brequinar and leflunomide. The immunophilin-binding drugs are cyclosporine, tacrolimus and rapamycin. Antibody preparations such as ATG, ATGAM and OKT3, as well as the newer biological agents, which specifically bind to the IL-2 receptor, basiliximab and daclizumab, are discussed. The potential for biologicals which inhibit co-stimulation are also discussed. There may be dramatic changes in protocols used clinically as a result of these new agents over the next decade. The increasing understanding of the alloimmune response as well as the clinical use of these newer drugs promise even better long-term results.

Clinical outcome 10 years after infant heart transplantation

The feasibility of heart transplantation for infants has now been established. Clinical outcome data is necessary to assist in targeting areas for improvement and for counseling families considering this option. This report describes clinical outcome in 29 infant heart transplant recipients who have survived at least 10 years. A query of the transplant database, referring physicians and parental questionnaire was performed. Patient survival for the overall infant population is 64% at 13 years. Parents of 19/29 (55%) children described them as developmentally normal. Three children have had a severe developmental outcome. Sixteen of 29 children are in mainstream school environments. Four have repeated one grade in school. Speech delay was present in 10/26 (38%). Somatic growth is normal in 88%. All children are NYHA class I. Renal function shows only modest insufficiency with most recent BUN (mean+/-S.D.)=25+/-7 mg/dl and serum creatinine=0.8+/-0.2 mg/dl. Only four children have creatinine levels >1 mg/dl. No child requires dialysis. No children have developed post-transplant lymphoproliferative disease beyond 10 years. Four children have experienced rejection beyond 10 years with one mortality due to rejection and transplant coronary artery disease. Conclusion: Heart transplantation during infancy is technically feasible and results in good survival. Many children have some degree of learning disability but most are mild and the children function well in society. Improvements in surgical techniques may improve developmental outcome. Other side-effects of immunosuppression are manageable and most survivors have a good functional outcome.

Neoral use in the pediatric transplant recipient

This review and critical analysis of current trends of immunosuppression management in pediatric transplantation provides evidence and support for the continued role of Neoral as an indispensable part of immunosuppressive protocols. CyA formulation influences clinical outcomes such as acute rejection, as confirmed by two studies. The CyA microemulsion formulation provides more reliable and effective absorption. An advanced TDM strategy to determine CyA bioavailability can improve the effectiveness and safety of immunosuppression in de novo liver transplant patients. especially in the younger de novo patient. Neoral is an indispensable part of combination protocols in pediatric transplantation.

Current results with pediatric heart transplantation

BACKGROUND

Cardiac transplantation is an accepted treatment for children with end-stage heart failure or complex or inoperable congenital defects.

METHODS

Since 1988, 95 transplants have been performed in 89 children aged 4 days to 18 years (median 6.9 years, 42 patients 0-5 years). Fifty-eight (61%) had congenital or acquired heart disease, 31 (33%) had idiopathic cardiomyopathy, and 6 (6%) were retransplants. Fifty-seven of the patients had prior cardiac surgery with a range of one to eight procedures (mean 3.4 procedures/patient). At the time of transplantation, 53 (56%) were United Network for Organ Sharing (UNOS) status I, including 23 children on mechanical ventilation and 4 with mechanical circulatory support.

RESULTS

Thirty-day survival in this group was 96%. Posttransplant results showed a median time of ventilation of 1 day (mean 3.0+/-5.7 days), median duration of inotropic support of 2 days (mean 2.7+/-2.3 days), median intensive care unit (ICU) stay of 4 days (mean 6.9+/-9.6 days), and median hospitalization of 9 days (mean 14.3+/-13.9 days). Follow-up from 1 month to 10.3 years (mean 3.1 years) has demonstrated a 1-year actuarial survival of 79% and a 5-year actuarial survival of 69%. Rejection, both acute and chronic, accounted for the vast majority of deaths.

CONCLUSIONS

Pediatric heart transplantation can be accomplished with excellent early survival despite multiple prior cardiac operations and relative severity of illness. Parameters such as postoperative ventilation, inotropic support, ICU stay, and hospitalization can be kept at reasonable levels with acceptable long-term results, although rejection remains a serious problem.