Current challenges in pediatric heart transplantation for congenital heart disease

Assessing Donor-Recipient Size Mismatch in Pediatric Heart Transplantation: Lessons Learned From Over 7,500 Transplants

BACKGROUND

To date, no studies have identified an optimal metric to match donor-recipient (D-R) pairs in pediatric heart transplantation (HT).

OBJECTIVES

This study sought to identify size mismatch metrics that predicted graft survival post-HT.

METHODS

D-R pairs undergoing HT in Pediatric Heart Transplant Society database from 1993 to 2021 were included. Effects of size mismatch by height, weight, body mass index, body surface area, predicted heart mass, and total cardiac volume (TCV) on 1- and 5-year graft survival and morbidity outcomes (rejection and cardiac allograft vasculopathy) were evaluated. Cox models with stepwise selection identified size metrics that independently predicted graft survival.

RESULTS

Of 7,715 D-R pairs, 36.0% were well matched (D-R ratio: -20% to +20%) by weight, 39.0% by predicted heart mass, 50.0% by body surface area, 57.0% by body mass index, 71.0% by height, and 93.0% by TCV. Of all size metrics, only D-R mismatch by height and TCV predicted graft survival at 1 and 5 years. Effects of D-R size mismatch on graft survival were nonlinear. At both 1 and 5 years post-HT, D-R undersizing and oversizing by height led to increased graft loss, with graft loss observed more frequently with undersizing. Moderately undersized donors by height (D-R ratio: <-30%) frequently experienced rejection post-HT (P < 0.001). Assessing D-R size matching by TCV, minimal donor undersizing was protective, while oversizing up to 25% was not associated with increased graft loss.

CONCLUSIONS

In pediatric HT, D-R appear most optimally matched using TCV. Only D-R size mismatch by TCV and height independently predicts graft survival. Standardizing size matching across centers may reduce donor discard.

Morbidity and Mortality of Heterotopic Partial Heart Transplantation in Rodent Models

Unrepairable congenital heart valve disease is an unsolved problem in pediatric cardiac surgery because there are no growing heart valve implants. Partial heart transplantation is a new type of transplant that aims to solve this problem. In order to study the unique transplant biology of partial heart transplantation, animal models are necessary. This study aimed to assess the morbidity and mortality of heterotopic partial heart transplantation in rodent models. This study assessed two models. The first model involved transplanting heart valves from donor animals into the abdominal aortic position in the recipient animals. The second model involved transplanting heart valve leaflets into the renal subcapsular position of the recipient animals. A total of 33 animals underwent heterotopic partial heart transplantation in the abdominal aortic position. The results of this model found a 60.61% (n = 20/33) intraoperative mortality rate and a 39.39% (n = 13/33) perioperative mortality rate. Intraoperative mortality was due to vascular complications from the procedure, and perioperative mortality was due to graft thrombosis. A total of 33 animals underwent heterotopic partial heart transplantation in the renal subcapsular position. The results of this model found a 3.03% (n = 1/33) intraoperative mortality rate, and the remaining 96.97% survived (n = 32/33). We conclude that the renal subcapsular model has a lower mortality rate and is technically more accessible than the abdominal aortic model. While the heterotopic transplantation of valves into the abdominal aortic position had significant morbidity and mortality in the rodent model, the renal subcapsular model provided evidence for successful heterotopic transplantation.

Systemic Venous Reconstructions During Pediatric Heart Transplantation

BACKGROUND

Congenital heart disease continues to be an important indication for pediatric heart transplantation (HT) and is often complicated by systemic venous anomalies. The need for reconstruction, surgical technique used, as well as the outcomes of these have limited documentation.

METHODS

Descriptive, retrospective study of patients transplanted at Emory University between 2006 and 2017. We reviewed surgical data, follow-up, and interventions for patients necessitating venous reconstruction during transplantation.

RESULTS

A total of 179 transplants were performed during the time period of which 74 (41%) required systemic venous reconstruction. Mean age at transplant was 6.3 (±6.16) years, and 74.3% of these patients carried a diagnosis of single ventricle; 51 (68.9%) of 74 patients required pulmonary artery reconstruction at the time of HT. Forty patients required superior vena caval reconstruction, while 22 patients required inferior vena caval reconstruction due to prior palliation or anomaly. Venous anomalies along with other anatomic features necessitated biatrial transplantation in four patients. Posttransplant evaluation revealed systemic venous stenosis in 14 (18.9%) of 74 patients. Eight (10.8%) patients required 12 interventions for the systemic veins. Patients with bilateral Glenn anastomosis prior to transplant were at high risk for the development of stenosis and needing interventions. Systemic venous complications were uncommon in those with native systemic veins without Glenn or Fontan procedure.

CONCLUSION

Systemic venous reconstruction needs are high in pediatric HT. Posttransplant stenosis and the need for interventions are relatively common. Current techniques for systemic venous reconstruction for complex congenital heart disease patients may deserve further review to optimize these outcomes.

Outcomes From Three Decades of Infant and Pediatric Heart Transplantation

Infants are a unique transplant population due to a suspected immunologic advantage, in addition to differences in size and physiology. Consequently, we expect infants to have significantly different diagnoses, comorbidities, and outcomes than pediatric transplant recipients. In this study, we compare patterns and trends in pediatric and infant heart transplantation during three decades. The United Network for Organ Sharing (UNOS) database was queried for transplants occurring between January 1990 and December 2018. Patients were categorized as pediatric (1-17) or infant (0-1). Congenital heart disease (CHD) primary diagnoses have increased from 37% to 42% in pediatric patients (p = 0.001) and decreased from 80% to 61% in infants during the 1990s and 2010s (p < 0.001). Those with CHD had worse outcomes in both age groups (p < 0.001). Infants who underwent ABO-incompatible transplants had similar survival as compared to those with compatible transplants (p = 0.18). Overall, infants had better long-term survival and long-term graft survival than pediatric patients; however, they had worse short-term survival (p < 0.001). Death due to rejection or graft failure was less likely in infants (p = 0.034). However, death from infection was over twice as common (p < 0.001). In summary, pediatric and infant heart transplant recipients differ in diagnoses, comorbidities, and outcomes, necessitating different care for these populations.

Pediatric heart transplantation in the current era

PURPOSE OF REVIEW

To provide an international perspective and current review of pediatric heart transplantation (PHTx).

RECENT FINDINGS

Waitlist survival and long-term outcomes in PHTx continue to improve. Strategies to maximize donor pool utilization include ABO incompatible listing for infants and expanded donor-to-recipient weight ranges. However, there is a high degree of practice variation internationally, from listing strategies and donor acceptance practices to chronic immunosuppression regimens, long-term graft surveillance, and consideration for retransplantation.

SUMMARY

Common indications for PHTx include end-stage congenital heart disease and cardiomyopathy. Current median graft survival among PHTx recipients ranges from 13 to 22 years. Common morbidities include infection, rejection, renal dysfunction, coronary allograft vasculopathy, and posttransplant lymphoproliferative disease. International registry data, collaborative initiatives to standardize management, and multicenter studies continue to improve knowledge and advancement of the field.

Exploring the developmental tasks of emerging adults after paediatric heart transplantation: a cross-sectional case control study

OBJECTIVE

Paediatric heart transplantation (PHTX) comprises 12% of all cardiac transplants and many of the children now survive into adulthood. Only a few studies have investigated the long-term psychosocial well-being of young adult patients after PHTX; no studies have investigated developmental tasks of emerging adulthood in different domains (family, social environment, education and profession, partnership, social environment).

SETTING

Specialised heart centre in Germany.

PARTICIPANTS

Thirty-eight young adults aged 22.11 years (SD=4.7) who underwent PHTX and a control group of 46 participants with no known chronic diseases, aged 22.91 years (SD=1.8), participated in the study.

OUTCOME MEASURES

All participants completed the following questionnaires: sociodemographic, the F-SozU, to measure perceived social support, the Gießener Beschwerde-Bogen to measure subjective complaints experienced by patients, the KIDSCREEN-27 to measure well-being and the SF-36 to measure health-related quality of life (QoL).

RESULTS

'Family': the quality of the relationship with the parents was found to be equal in both groups, while PHTX patients stayed in closer spatial proximity to their parents. 'Social environment': PHTX patients reported lower social support by peers than the control group. 'Education and profession': PHTX patients most often worked full-time (23%), had no job and/or received a pension (21%). In comparison, most of the healthy controls did an apprenticeship (40%) and/or worked part time (32%). 'Partnership': fewer of the PHTX patients had a partner than the control group while relationship duration did not differ. In exploratory regression analyses, social support by peers predicted physical QoL, whereas physical complaints and the physical role predicted mental QoL in PHTX patients.

CONCLUSIONS

Our exploratory findings highlight important similarities and differences in specific developmental tasks between PHTX patients and healthy controls. Future studies should focus on developmental tasks of PHTX patients in this age group more systematically, investigating their role in physical and mental well-being in a confirmatory manner.

Psychosocial predictors of medication non-adherence in pediatric organ transplantation: A systematic review

Adherence to immunosuppressant medication is critical to health and quality-of-life outcomes for children who have received a solid organ transplant. Research on the psychological and social predictors of medication adherence is essential to the advancement of pretransplant assessments and transplant psychosocial services. Despite the importance of identifying risk factors, the literature remains limited regarding psychosocial predictors of non-adherence. A systematic search was conducted to identify studies of the psychosocial predictors of post-transplant medication non-adherence in pediatric solid organ transplantation. From 1363 studies identified in searches of empirical literature, a final sample consisted of 54 publications representing 49 unique studies. Findings regarding psychosocial predictors were inconsistent with non-adherence associated largely with adolescence, racial/ethnic minority status, and presence of mental health issues. Familial predictors of non-adherence problems included single-parent households, lower socioeconomic status, lower family cohesion, presence of family conflict, and poor family communication. Several studies reported an association between non-adherence and social pressures (eg, peer social interaction, wanting to feel normal) among adolescent transplant recipients. While significant methodological and substantive gaps remain in this body of knowledge, this review synthesizes current evidence for assessment for transplant clinicians and researchers.

Identifiable Risk Factors and Miscalculations During Listing for Pediatric Heart Transplantation

The objective of this study is to describe identifiable risk factors, complications, and pitfalls while listing pediatric patients for heart transplantation, which is the standard of care for end-stage heart disease in children. Since the introduction of cyclosporine in the 1980s, the management in pediatric heart transplantation has shown consistent improvement, mainly because of technological advances and the integration of multidisciplinary teams in the field. However, the complexity of this patient population makes medical providers vulnerable to complications as a result of undesirable mistakes. Transplant survival is impacted negatively when mistakes from health-care providers compound the high-risk status of the patient. The identification of multiple risk factors and undesirable miscalculations may help transplant teams make decisions before allocating organs, intervene or minimize morbidity, and provide the best quality of life to recipients.

Neonatal heart transplantation

Neonatal heart transplantation was developed and established in the 1980's as a durable modality of therapy for complex-uncorrectable heart disease. Patients transplanted in the neonatal period have experienced unparalleled long-term survival, better than for any other form of solid-organ transplantation. However, the limited availability of neonatal and young infant donors has restricted the indications and applicability of heart transplantation among newborns in the current era. Indications for heart transplantation include congenital heart disease not amenable to other forms of surgical palliation, and cardiomyopathy, including some primary tumors. Use of ABO-incompatible transplants, and organs with prolonged cold ischemic time or marginal function have all been associated with good outcomes in infants. These extended strategies to increase the donor pool may also someday include donation after determination of circulatory death and the use of anencephalic donors. The operative techniques for donors and recipients of neonatal heart transplantation are unique and have been well-described. Immunosuppression protocols for neonates need not include induction and are largely steroid-free. Newborn and young infant transplant recipients have fewer episodes of rejection, less coronary allograft vasculopathy, less post-transplant lymphoproliferative disease and less renal dysfunction than their older counterparts. Long-term outcomes have been very encouraging in terms of graft survival, patient survival, and quality of life. Our review highlights the history, current indications, techniques and outcomes of heart transplantation in this immunologically-privileged subset of patients.

Maintaining the Gift of Life: Achieving Adherence in Adolescent Heart Transplant Recipients

Since the beginning of United Network of Organ Sharing data collection in 1987, a total of 8,333 pediatric patients have received a heart transplant in the United States. Because these patients now have longer graft success with improved care and immunosuppression, many of them are entering adolescence and young adulthood. Primary care pediatric nurse practitioners need to be alert to the prevalence of noncompliance with treatment in heart transplant patients, which continues to be highest in adolescence. Low compliance in adolescence increases morbidity, contributes to decreasing quality of life, and is the leading reason for graft failure and mortality in this age group. This article will review common barriers to treatment adherence in the adolescent heart transplant patient, discuss the role of the primary care pediatric nurse practitioner in preventing noncompliance, and review strategies that the primary care pediatric nurse practitioner can implement to improve compliance in this patient population.