Pediatric heart transplantation-indications and outcomes in the current era

A Review of Pediatric Cardiomyopathy

Though pediatric cardiomyopathy is rare in children, there is significant associated morbidity and mortality. Etiology varies from inborn errors of metabolism to familial genetic mutations and myocyte injury. Major classes include dilated, hypertrophic, restrictive, and non-compaction. Diagnosis generally involves a combination of clinical history and echocardiography. The use of cross-sectional imaging is gaining popularity. Management varies between subtype and may involve a combination of medical and surgical interventions depending on clinical status.

A Systematic Review of Adherence to Immunosuppression among Pediatric Heart Transplant Patients

After pediatric heart transplant, commitment to lifelong immunosuppression is crucial to maintaining graft health. However, a review of the current literature surrounding adherence to immunosuppression in pediatric heart transplant patients is lacking. This systematic review aims to summarize the current landscape of adherence to immunosuppression in pediatric heart transplant patients. We conducted searches in PubMed MEDLINE, Embase, CENTRAL register of Controlled Trials (Wiley), and Scopus, from inception to March 2020. Studies were eligible if they outlined an aspect of adherence to immunosuppression and the measurement of adherence was performed with an objective or otherwise validated measure of adherence (e.g., drug levels, adherence questionnaires). The titles/abstracts of 880 articles were reviewed. After initial screening, 106 articles underwent full text review. As such, 14 articles were included in the final review. Baseline adherence estimates varied greatly, with most values between 40% and 70%. Nonadherence to immunosuppression is associated with worse outcomes (rejection, hospitalization, mortality), impaired quality of life, and mental health concerns in pediatric heart transplant patients. As nonadherence to immunosuppression is common and associated with worse outcomes, there is a need for further development and evaluation of interventions in this space.

Tissue engineering: Relevance to neonatal congenital heart disease

Congenital heart disease (CHD) represents a large clinical burden, representing the most common cause of birth defect-related death in the newborn. The mainstay of treatment for CHD remains palliative surgery using prosthetic vascular grafts and valves. These devices have limited effectiveness in pediatric patients due to thrombosis, infection, limited endothelialization, and a lack of growth potential. Tissue engineering has shown promise in providing new solutions for pediatric CHD patients through the development of tissue engineered vascular grafts, heart patches, and heart valves. In this review, we examine the current surgical treatments for congenital heart disease and the research being conducted to create tissue engineered products for these patients. While much research remains to be done before tissue engineering becomes a mainstay of clinical treatment for CHD patients, developments have been progressing rapidly towards translation of tissue engineering devices to the clinic.

Congenital Heart Disease: An Immunological Perspective

Congenital heart disease (CHD) poses a significant global health and economic burden-despite advances in treating CHD reducing the mortality risk, globally CHD accounts for approximately 300,000 deaths yearly. Children with CHD experience both acute and chronic cardiac complications, and though treatment options have improved, some remain extremely invasive. A challenge in addressing these morbidity and mortality risks is that little is known regarding the cause of many CHDs and current evidence suggests a multifactorial etiology. Some studies implicate an immune contribution to CHD development; however, the role of the immune system is not well-understood. Defining the role of the immune and inflammatory responses in CHD therefore holds promise in elucidating mechanisms underlying these disorders and improving upon current diagnostic and treatment options. In this review, we address the current knowledge coinciding CHDs with immune and inflammatory associations, emphasizing conditions where this understanding would provide clinical benefit, and challenges in studying these mechanisms.

Quantitative cardiac magnetic resonance T2 imaging offers ability to non-invasively predict acute allograft rejection in children

BACKGROUND

Monitoring for acute allograft rejection improves outcomes after cardiac transplantation. Endomyocardial biopsy is the gold standard test defining rejection, but carries risk and has limitations. Cardiac magnetic resonance T2 mapping may be able to predict rejection in adults, but has not been studied in children. Our aim was to evaluate T2 mapping in identifying paediatric cardiac transplant patients with acute rejection.

METHODS

Eleven paediatric transplant patients presenting 18 times were prospectively enrolled for non-contrast cardiac magnetic resonance at 1.5 T followed by endomyocardial biopsy. Imaging included volumetry, flow, and T2 mapping. Regions of interest were manually selected on the T2 maps using the middle-third technique in the left ventricular septal and lateral wall in a short-axis and four-chamber slice. Mean and maximum T2 values were compared with Student's t-tests analysis.

RESULTS

Five cases of acute rejection were identified in three patients, including two cases of grade 2R on biopsy and three cases of negative biopsy treated for clinical symptoms attributed to rejection (new arrhythmia, decreased exercise capacity). A monotonic trend between increasing T2 values and higher biopsy grades was observed: grade 0R T2 53.4 ± 3 ms, grade 1R T2 54.5 ms ± 3 ms, grade 2R T2 61.3 ± 1 ms. The five rejection cases had significantly higher mean T2 values compared to cases without rejection (58.3 ± 4 ms versus 53 ± 2 ms, p = 0.001).

CONCLUSIONS

Cardiac magnetic resonance with quantitative T2 mapping may offer a non-invasive method for screening paediatric cardiac transplant patients for acute allograft rejection. More data are needed to understand the relationship between T2 and rejection in children.

Variations in Criteria and Practices for Heart Transplantation Listing Among Pediatric Transplant Cardiologists

Ethical issues in pediatric heart transplantation (Htx) include resource allocation, benefit, and burden assessment in high-risk recipients, and informed consent. Practice patterns and decision-making was investigated using an internet survey with 47-multiple choice items and vignette-based questions. Of 43 pediatric Htx cardiologists contacted, 28 (65%) responded. Respondents reported that an overall median 1-month survival of 73% (range 50-100%), 1-year survival of 70% (range 50-85%), 5-year survival of 50% (range 40-85%), and 10-year survival of 50% (range 25-85%) was adequate to offer Htx. Based on vignettes presented, 100% of those surveyed would offer Htx to a straightforward 12-year old with end-stage dilated cardiomyopathy and a 7-year old with hypoplastic left heart syndrome with protein losing enteropathy. Thirty percent of physicians would offer Htx to a patient status post a Fontan procedure with mutliple co-morbidities. Seventy-five percent of physicians would offer Htx despite proven non-adherence. Considerable variability exists in the practice patterns of pediatric heart transplant cardiologists with regards to decision-making while evaluating patients for listing. Disagreements among pediatric Htx cardiologists exist when there are concerns for non-adherence and associated multiple co-morbidities. Further work is needed to understand these variations and develop consensus for pediatric Htx organ allocation.

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.

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.

Selection of Patients for Initial Clinical Trials of Solid Organ Xenotransplantation

Several groups have reported extended survival of genetically engineered pig organs in nonhuman primates, varying from almost 10 months for life-supporting kidney grafts and more than 2 years for non-life-supporting heart grafts to less than 1 month for life-supporting liver and lung grafts. We have attempted to define groups of patients who may not have an option to wait for an allograft. These include kidney, heart, and lung candidates who are highly-allosensitized. In addition, some kidney candidates (who have previously lost at least 2 allografts from rapid recurrence of native kidney disease) have a high risk of further recurrence and will not be offered a repeat allotransplant. Patients with complex congenital heart disease, who may have undergone previous palliative surgical procedures, may be unsuitable for ventricular assist device implantation. Patients dying of fulminant hepatic failure, for whom no alternative therapy is available, may be candidates for a pig liver, even if only as a bridge until an allograft becomes available. When the results of pig organ xenotransplantation in nonhuman primates suggest a realistic potential for success of a pilot clinical trial, highly selected patients should be offered participation.

Exosomes from pediatric dilated cardiomyopathy patients modulate a pathological response in cardiomyocytes

Stimulation of the renin-angiotensin-aldosterone system (RAAS) and β-adrenergic receptors plays an important role in adult heart failure (HF). Despite the demonstrated benefits of RAAS inhibition and β-adrenergic receptor blockade in adult HF patients, no substantial improvement in survival rate has been observed in children with HF. This suggests that the underlying disease mechanism is uniquely regulated in pediatric HF. Here, we show that treatment of human-induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) and neonatal rat ventricular myocytes (NRVMs) with serum from pediatric dilated cardiomyopathy (DCM) patients induces pathological changes in gene expression, which occur independently of the RAAS and adrenergic systems, suggesting that serum circulating factors play an important role in cardiac remodeling. Furthermore, exosomes purified from DCM serum induced pathological changes in gene expression in NRVMs and iPSC-CMs. Our results suggest that DCM serum exosomes mediate pathological responses in cardiomyocytes and may propagate the pediatric HF disease process, representing a potential novel therapeutic target specific to this population.NEW & NOTEWORTHY The results of this work could alter the present paradigm of basing clinical pediatric heart failure (HF) treatment on outcomes of adult HF clinical trials. The use of serum-treated primary cardiomyocytes may define age-specific mechanisms in pediatric HF with the potential to identify unique age-appropriate and disease-specific therapy.

Pediatric Pulseless Ventricular Tachycardia: A Simulation Scenario for Fellows, Residents, Medical Students, and Advanced Practitioners

INTRODUCTION

Pulseless ventricular tachycardia is an uncommon presentation to the pediatric emergency department (ED) or the pediatric ICU (PICU); however, if unrecognized or inappropriately treated, it can lead to significant morbidity and mortality. This resource was created to simulate a high-acuity and low-frequency event targeting PICU fellows, pediatric emergency medicine fellows, pediatric residents, ED residents, medical students, and advanced nursing providers.

METHODS

This scenario details the case of a 12-year-old boy with a history of heart transplant who presents with the chief complaint of dizziness. He initially has multiple premature ventricular contractions and then progresses to pulseless ventricular tachycardia due to acute rejection. This simulation may be performed in a simulation lab or in situ in the ICU or ED. Necessary personnel include a simulation technician, instructors, and a nurse. A code cart and defibrillator with hands-free pads appropriate for the mannequin are needed supplies. Critical actions include cardiopulmonary resuscitation, defibrillation with three shocks, and administration of anti-arrhythmic. At the end of the scenario, a formal debriefing and learner assessment with structured feedback are performed.

RESULTS

Approximately 110 learners have completed this module during 18 separate sessions. Written evaluation from participants (n = 94) using a Likert scale (1 = not at all, 4 = to a great extent) shows that the objectives of the simulation are met to a great extent, with an average score of 3.8.

DISCUSSION

In conclusion, this resource advances learner knowledge and comfort when managing a pediatric patient with pulseless ventricular tachycardia, reviews appropriate management, and helps identify knowledge deficits in the management of these patients.

Late outcome after paediatric heart transplantation in Finland

OBJECTIVES

We studied the long-term survival and rejection episodes of paediatric heart transplant recipients.

METHODS

We included all paediatric patients (≤18 years) who underwent heart transplantation during 1991-2014 in Finland. Data were obtained retrospectively from a paediatric cardiac surgery database. Patient status was received from the Finnish population registry. All patients underwent yearly routine postoperative endomyocardial biopsies and coronary angiographies.

RESULTS

Between 1991 and 2014, 68 heart transplantations were performed. The early mortality (<30 days after surgery) rate was 10% and follow-up coverage was 100%. The 10- and 15-year survival rates for all patients were 68% (95% confidence internal, CI, 56-80%) and 65% (95% CI 53-78%), respectively, including early mortality. The 1-year survival rate was 100% when excluding early operative mortality. Indications for heart transplantation were cardiomyopathy in 57% and cardiac malformations in 43% of patients, with similar long-term survival between the groups. During 23 years of follow-up, 43 patients (70%) had at least one rejection episode and 17 patients (29%) at least a grade 1 coronary artery vasculopathy finding. Patients with early rejection episodes (<3 months) had a higher incidence of late rejection episodes (P = 0.025). Older age at operation was a significant risk factor for the development of coronary artery vasculopathy (hazard ratio 1.1, 95% CI 1.0-1.3, P = 0.012).

CONCLUSIONS

First-year survival was excellent. Asymptomatic rejection episodes were common among patients. Early rejection episodes are a risk factor for late rejection episodes and show a trend towards an increased risk of late death. Coronary artery vasculopathy remains a major challenge for late graft survival.