Pediatric Cardiac Xenotransplantation: Recommendations for the Ethical Design of Clinical Trials.

For children with complex congenital heart problems, cardiac allotransplantation is sometimes the best therapeutic option. However, availability of hearts for pediatric patients is limited, resulting in a long and growing waitlist, and a high mortality rate while waiting. Cardiac xenotransplantation has been proposed as one therapeutic alternative for neonates and infants, either in lieu of allotransplantation or as a bridge until an allograft becomes available. Scientific and clinical developments in xenotransplantation appear likely to permit cardiac xenotransplantation clinical trials in adults in the coming years. The ethical issues around xenotransplantation of the heart and other organs and tissues have recently been examined, but to date, only limited literature is available on the ethical issues that are attendant with pediatric heart xenotransplantation. Here, we summarize the ethical issues, focusing on (1) whether cardiac xenotransplantation should proceed in adults or children first, (2) pediatric recipient selection for initial xenotransplantation trials, (3) special problems regarding informed consent in this context, and (4) related psychosocial and public perception considerations. We conclude with specific recommendations regarding ethically informed design of pediatric heart xenotransplantation trials.

The American Association for Thoracic Surgery (AATS) 2023 Expert Consensus Document: Recommendation for the care of children with trisomy 13 or trisomy 18 and a congenital heart defect.

OBJECTIVES: Recommendations for surgical repair of a congenital heart defect in children with trisomy 13 or trisomy 18 remain controversial, are subject to biases, and are largely unsupported with limited empirical data. This has created significant distrust and uncertainty among parents and could potentially lead to suboptimal care for patients. A working group, representing several clinical specialties involved with the care of these children, developed recommendations to assist in the decision-making process for congenital heart defect care in this population. The goal of these recommendations is to provide families and their health care teams with a framework for clinical decision making based on the literature and expert opinions. METHODS: This project was performed under the auspices of the AATS Congenital Heart Surgery Evidence-Based Medicine Taskforce. A Patient/Population, Intervention, Comparison/Control, Outcome process was used to generate preliminary statements and recommendations to address various aspects related to cardiac surgery in children with trisomy 13 or trisomy 18. Delphi methodology was then used iteratively to generate consensus among the group using a structured communication process. RESULTS: Nine recommendations were developed from a set of initial statements that arose from the Patient/Population, Intervention, Comparison/Control, Outcome process methodology following the groups' review of more than 500 articles. These recommendations were adjudicated by this group of experts using a modified Delphi process in a reproducible fashion and make up the current publication. The Class (strength) of recommendations was usually Class IIa (moderate benefit), and the overall level (quality) of evidence was level C-limited data. CONCLUSIONS: This is the first set of recommendations collated by an expert multidisciplinary group to address specific issues around indications for surgical intervention in children with trisomy 13 or trisomy 18 with congenital heart defect. Based on our analysis of recent data, we recommend that decisions should not be based solely on the presence of trisomy but, instead, should be made on a case-by-case basis, considering both the severity of the baby's heart disease as well as the presence of other anomalies. These recommendations offer a framework to assist parents and clinicians in surgical decision making for children who have trisomy 13 or trisomy 18 with congenital heart defect.

Hybrid Thrombectomy and Central Extracorporeal Membrane Oxygenation for Massive Pulmonary Embolism in a Child.

We describe a hybrid thrombectomy and central extracorporeal membrane oxygenation for a child in cardiogenic shock due to a massive pulmonary embolism.

A descriptive assessment of the informed consent document used by congenital cardiac surgery centres.

BACKGROUND: Informed consent for surgery is a complex process particularly in paediatrics. Complexity increases with procedures such as CHD surgery. Regulatory agencies outline informed consent contents for surgery. We assessed and described CHD surgical informed consent contents through survey dissemination to paediatric CHD centres across United States of America. METHODS: Publicly available email addresses for 125 paediatric cardiac clinicians at 70 CHD surgical centres were obtained. Nine-item de-identified survey assessing adherence to The Joint Commission informed consent standards was created and distributed via RedCap® 14 March, 2023. A follow-up email was sent 29 March, 2023. Survey link was closed 18 April, 2023. RESULTS: Thirty-seven surveys were completed. Results showed informed consent documents were available in both paper (25, 68%) and electronic (3, 8%) format. When both (9, 24%) formats were available, decision on which format to use was based on centre protocols (1, 11%), clinician personal preference (3, 33%), procedure being performed (1, 11%), or other (4, 45%). Five (13%) centres' informed consent documents were available only in English, with 32 (87%) centres also having a Spanish version. Review of informed consent documents demonstrated missing The Joint Commission elements including procedure specific risks, benefits, treatment alternatives, and expected outcomes. CONCLUSIONS: Informed consent for CHD surgery is a complex process with multiple factors involved. Majority of paediatric CHD surgical centres in the United States of America used a generic informed consent document which did not uniformly contain The Joint Commission specified information nor reflect time spent in discussion with families. Further research is needed on parental comprehension during the informed consent process.

Central ECMO cannulation for severe dihydropyridine calcium channel blocker overdose.

Calcium channel blocker (CCB) toxicity carries a high mortality and is the sixth most fatal drug class reported to US poison centers. Amlodipine overdose is characterized by a life-threatening arterial vasodilation that compromises organ perfusion. The management of CCB intoxication is focused on maintaining adequate organ perfusion. In cases refractory to medical therapies, hemodynamic support with extracorporeal membrane oxygenation (ECMO) is warranted necessitating higher flows than usual to compensate for the vasodilation and requiring central cannulation. We present a case of a 12-year-old with severe dihydropyridine CCB ingestion, refractory to medical management and successfully treated with central ECMO cannulation. The patient was discharged home with no significant disability. Central ECMO cannulation may be helpful to facilitate adequate flows in vasodilatory shock such as CCB overdose.

Central Extracorporeal Membrane Oxygenation Support Following Calcium Channel Blocker Overdose in Children.

Refractory vasodilatory shock (RVS) following massive calcium channel blocker (CCB) overdose remains a challenging clinical entity. Peripheral venoarterial extracorporeal membrane oxygenation (ECMO) has proven useful in several cases of CCB intoxication, however, its use in the pediatric population poses unique challenges given the generally small size of pediatric peripheral vasculature in comparison to the high flow rates necessary for adequate mechanical circulatory support. As a result of these challenges, our group has adopted a "primary" central ECMO cannulation approach to the treatment of children and adolescents admitted to our center with profound RVS after CCB ingestion. We present four cases within the last year using this approach. All patients were successfully discharged from the hospital with no late morbidity at most recent follow-up. Central ECMO support in cases of massive vasodilatory shock following CCB overdose is safe and effective and should be considered early in the clinical course of these critically ill patients.

Hybrid Norwood for Hypoplastic Left Heart Syndrome With Rare Aortic Arch Anatomy.

We describe the hybrid Norwood as first-stage palliation for a patient with hypoplastic left heart syndrome, right aortic arch, right descending aorta, bilateral ductus arteriosus, and left innominate artery arising from the left ductus.

Surgical Experience With Nine Cases of Obstructed Right Aortic Arch.

BACKGROUND: Right-sided aortic arch obstruction is an extremely rare congenital anomaly. A variety of surgical approaches have been described. This study reviews our institutional experience over the last 30 years. METHODS: Our surgical database at the University of Alabama at Birmingham and Children's Hospital of Alabama from 1992 to 2022 was reviewed to include all patients who underwent surgical repair for right-sided aortic arch obstruction. RESULTS: A total of nine patients underwent surgical repair for right-sided aortic arch obstruction. Surgical approach was via thoracotomy (n = 2, 22%), sternotomy (n = 5, 56%), or combined (n = 2, 22%). Primary extended end-to-end anastomosis was utilized for patients with discrete coarctation (n = 1, 11%), reverse subclavian flap for coarctation with associated distal arch hypoplasia (n = 2, 22%), GORE-TEX® tube graft for circumflex aorta (n = 1, 11%), and aortic arch advancement (n = 5, 56%) with or without patch augmentation for those with an interrupted or severely hypoplastic aortic arch. Reintervention was required in one patient (11%) for recoarctation. All patients were discharged in good condition. There was no hospital mortality and at 10.5 years (mean) follow-up there was one late death. CONCLUSION: Right aortic arch obstruction is a rare entity. Surgical approach should be tailored to the anatomy and associated intracardiac defects. Preoperative imaging with a CT angiogram is useful for operative planning. Sternotomy with single-stage primary repair is safe, effective, and our preferred surgical approach for patients with right aortic arch obstruction and associated intracardiac pathology.

Association Between Venous Homografts and Allosensitization After Norwood Procedure.

BACKGROUND: Right ventricle (RV) to pulmonary artery (PA) shunts have become the shunt of choice at many centers for use during the Norwood procedure for single ventricle palliation. Some centers have begun to use cryopreserved femoral or saphenous venous homografts as an alternative to polytetrafluoroethylene (PTFE) for shunt construction. The immunogenicity of these homografts is unknown, and potential allosensitization could have significant implications on transplant candidacy. METHODS: All patients undergoing Glenn procedure at our center between 2013 and 2020 were screened. Patients who initially underwent Norwood procedure with either PTFE or venous homograft RV-PA shunt and had available pre-Glenn serum were included in the study. The primary outcome of interest was panel reactive antibody (PRA) level at the time of Glenn surgery. RESULTS: Thirty-six patients met inclusion criteria (N = 28 PTFE, N = 8 homograft). Patients in the homograft group had significantly higher median PRA levels at the time of Glenn surgery (0% [IQR 0-18] PTFE vs 94% [IQR 74-100] homograft, P = .003). There were no other differences between the two groups. CONCLUSIONS: Despite potential improvements in PA architecture, the use of venous homografts for RV-PA shunt construction at the time of Norwood procedure is associated with significantly elevated PRA level at the time of Glenn surgery. Centers should carefully consider the use of currently available venous homografts given the high percentage of these patients who may require future transplantation.

Norwood Operation: Immediate vs Delayed Sternal Closure.

BACKGROUND: The Norwood operation is a complex neonatal surgery. There are limited data to inform the timing of sternal closure. After the Norwood operation, delayed sternal closure (DSC) is frequent. We aimed to examine the association of DSC with outcomes, with a particular interest in how sternal closure at the time of surgery compared with the timing of DSC. Our outcomes included mortality, length of ventilation, length of stay, and postoperative complications. METHODS: This retrospective study included neonates who underwent a Norwood operation reported in the Pediatric Cardiac Critical Care Consortium registry from February 2019 through April 2021. Outcomes of patients with closed sternum were compared to those with sternal closure prior to postoperative day 3 (early closure) and prior to postoperative day 6 (intermediate closure). RESULTS: The incidence of DSC was 74% (500 of 674). The median duration of open sternum was 4 days (interquartile range 3-5 days). Comparing patients with closed sternum to patients with early sternal closure, there was no statistical difference in mortality rate (1.1% vs 0%) and the median hospital postoperative stay (30 days vs 31 days). Compared with closed sternum, patients with intermediate sternal closure required longer mechanical ventilation (5.9 days vs 3.9 days) and fewer subsequent sternotomies (3% vs 7.5%). CONCLUSIONS: For important outcomes following the Norwood operation there is no advantage to chest closure at the time of surgery if the chest can be closed prior to postoperative day 3.

Health-Related Quality of Life After Single Ventricle Palliation or Tetralogy of Fallot Repair.

Single ventricle (SV) cardiac lesions and tetralogy of Fallot (TOF) are both common forms of cyanotic congenital heart disease. With advances in perioperative care and longitudinal follow-up, survival of these patients has dramatically improved and the majority survive to adulthood. This study compares health-related quality of life (HRQoL) of adult SV and TOF patients to each other and the general population. HRQoL of all surviving, non-transplanted SV and TOF patients 21 years of age and older at our institution was assessed with the SF-36 questionnaire via phone. Additional data including demographic parameters and information related to comorbidities and healthcare utilization were also analyzed. Among 81 eligible SV patients and 207 TOF patients, 33 (41%) and 75 (36%) completed the SF-36 phone survey, respectively. The mean age of SV patients was 32 vs. 38 years in the TOF group (p=0.01). SV patients reported more hepatic, pulmonary, and renal comorbidities. TOF patients were more likely to complete advanced degrees and more likely to have children (p=0.03). SV physical functioning scores were worse compared to TOF. In other domains of the SF-36 questionnaire, SV and TOF scores were similar. Compared to the general population, both groups reported worse bodily pain and mental health, but other aspects of psychosocial and general health were comparable. Overall HRQoL is good for both SV and TOF patients through early and mid-adulthood. Some QoL metrics were modestly worse in the SV patients. While these patients may have some physical limitations, psychosocial wellbeing appears preserved.

Will previous palliative surgery for congenital heart disease be detrimental to subsequent pig heart xenotransplantation?

INTRODUCTION: Pig heart xenotransplantation might act as a bridge in infants with complex congenital heart disease (CHD) until a deceased human donor heart becomes available. Infants develop antibodies to wild-type (WT, i.e., genetically-unmodified) pig cells, but rarely to cells in which expression of the 3 known carbohydrate xenoantigens has been deleted by genetic engineering (triple-knockout [TKO] pigs). Our objective was to test sera from children who had undergone palliative surgery for complex CHD (and who potentially might need a pig heart transplant) to determine whether they had serum cytotoxic antibodies against TKO pig cells. METHODS: Sera were obtained from children with CHD undergoing Glenn or Fontan operation (n = 14) and healthy adults (n = 8, as controls). All of the children had complex CHD and had undergone some form of cardiac surgery. Seven had received human blood transfusions and 3 bovine pericardial patch grafts. IgM and IgG binding to WT and TKO pig red blood cells (RBCs) and peripheral blood mononuclear cells (PBMCs) were measured by flow cytometry, and killing of PBMCs by a complement-dependent cytotoxicity assay. RESULTS: Almost all children and adults demonstrated relatively high IgM/IgG binding to WT RBCs, but minimal binding to TKO RBCs (p < 0.0001 vs WT), although IgG binding was greater in children than adults (p < 0.01). All sera showed IgM/IgG binding to WT PBMCs, but this was much lower to TKO PBMCs (p < 0.0001 vs WT) and was greater in children than in adults (p < 0.05). Binding to both WT and TKO PBMCs was greater than to RBCs. Mean serum cytotoxicity to WT PBMCs was 90% in both children and adults, whereas to TKO PBMCs it was only 20% and < 5%, respectively. The sera from 6/14 (43%) children were cytotoxic to TKO PBMCs, but no adult sera were cytotoxic. CONCLUSIONS: Although no children had high levels of antibodies to TKO RBCs, 13/14 demonstrated antibodies to TKO PBMCs, in 6 of these showed mild cytotoxicity. As no adults had cytotoxic antibodies to TKO PBMCs, the higher incidence in children may possibly be associated with their exposure to previous cardiac surgery and biological products. However, the numbers were too small to determine the influence of such past exposures. Before considering pig heart xenotransplantation for children with CHD, testing for antibody binding may be warranted.

The Genetically Engineered Heart as a Bridge to Allotransplantation in Infants Just Around the Corner?

BACKGROUND: Mortality for infants on the heart transplant waitlist remains unacceptably high, and available mechanical circulatory support is suboptimal. Our goal is to demonstrate the feasibility of utilizing genetically engineered pig (GEP) heart as a bridge to allotransplantation by transplantation of a GEP heart in a baboon. METHODS: Four baboons underwent orthotopic cardiac transplantation from GEP donors. All donor pigs had galactosyl-1,3-galactose knocked out. Two donor pigs had human complement regulatory CD55 transgene and the other 2 had human complement regulatory CD46 and thrombomodulin. Induction immunosuppression included thymoglobulin, and anti-CD20. Maintenance immunosuppression was rapamycin, anti-CD-40, and methylprednisolone. One donor heart was preserved with University of Wisconsin solution and the other three with del Nido solution. RESULTS: All baboons weaned from cardiopulmonary bypass. B217 received a donor heart preserved with University of Wisconsin solution. Ventricular arrhythmias and depressed cardiac function resulted in early death. All recipients of del Nido preserved hearts easily weaned from cardiopulmonary bypass with minimal inotropic support. B15416 and B1917 survived for 90 days and 241 days, respectively. Histopathology in B15416 revealed no significant myocardial rejection but cellular infiltrate around Purkinje fibers. Histopathology in B1917 was consistent with severe rejection. B37367 had uneventful transplant but developed significant respiratory distress with cardiac arrest. CONCLUSIONS: Survival of B15416 and B1917 demonstrates the feasibility of pursuing additional research to document the ability to bridge an infant to cardiac allotransplant with a GEP heart.

Outcomes in Pediatric Post-Cardiotomy ECMO Support With Modification of Systematic Support Strategy.

BACKGROUND: Utilization of extracorporeal membrane oxygenation (ECMO) support in the post-cardiotomy setting is vital to successful perioperative outcomes following pediatric cardiac surgery. Specific analysis of protocolized management strategies and staff preparedness is imperative to optimizing institutional ECMO outcomes. METHODS: All patients requiring post-cardiotomy ECMO support at a single institution from 2013 to 2019 were retrospectively reviewed. In 2015, several modifications were made to the ECMO support paradigm that addressed deficiencies in equipment, critical care protocols, and staff preparedness. Cases were stratified according to era of ECMO support; patients supported prior to paradigm change from 2013 to 2015 (Group EARLY, n = 20), and patients supported following the implementation of systematic modifications from 2016 to 2019 (Group LATE, n = 26). The primary outcomes of interest were survival to decannulation and hospital discharge. RESULTS: Median age at cannulation was 24.5 days (IQR 7-96) and median duration of support was 4 days (IQR 2-8). Overall survival to decannulation was 78.3% (65% EARLY vs. 88.5% LATE, P = .08) and overall survival to hospital discharge was 58.7% (35% EARLY vs. 76.9% LATE, P = .004). CONCLUSION: Systematic modifications to ECMO support strategy and staff preparation are associated with a significant increase in perioperative survival for pediatric patients requiring post-cardiotomy ECMO support.

Tachyarrhythmia as a possible symptom of coronavirus in a neonate diagnosed with transposition of the great arteries.

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic poses broad challenges to healthcare systems and providers. The manifestations of this disease are still being described in a variety of different contexts and patient populations. RESULTS: We report the case of a neonate who demonstrated COVID-19 after surgical correction of transposition of the great arteries. In addition, the patient demonstrated an evolving and persistent tachyarrhythmia consistent with neither the most likely postoperative complications nor typical COVID-19. DISCUSSION: The patient had negative preoperative testing for the virus and presented with profound oxygen desaturation and respiratory failure several days postoperatively. This raised concern for a complication of his arterial switch operation. It was found that one of the patient's caregivers was an asymptomatic carrier of COVID-19, and imaging ruled out intracardiac shunting. After initiating treatment for COVID-19, the patient's oxygen requirements and need for anti-arrhythmic agents improved. CONCLUSION: We propose that, despite negative preoperative testing, coronavirus infection may present as refractory tachyarrhythmia, and may be considered along with surgical complications as a cause for unexplained hypoxemia postoperatively.

Gender Differences in Cardiothoracic Surgery Interest Among General Surgery Applicants.

BACKGROUND: Although the overall gender gap in medicine is narrowing, significant gender disparities remain in the cardiothoracic surgery (CTS) field; women represent only 7% of practicing surgeons and 20% of residents. The purpose of this study was to identify gender differences in CTS exposure and interest among fourth year medical students applying to general surgery residency. METHODS: An anonymous survey was emailed to general surgery residency applicants at a major academic program for the 2019 and 2020 application cycles. Data were stratified by gender and analyzed using the χ2 and t tests. RESULTS: Of the 303 responders to the survey, 44% were women. A total of 58% of women were unlikely to be interested in or were definitely not interested in pursuing a career in CTS compared with 35% of men (P < .05). Men were 2.5 times more likely than women to be interested in CTS (odds ratio, 2.5; 95% confidence interval, 1.5 to 4.1). More men had rotated through CTS (55% vs 44%; P = .04) and shadowed a cardiothoracic surgeon (41% vs 29%; P = .03). More than 30% of women interested in CTS reported mentorship as the most important factor in their decision. Mentorship and CTS rotations were both independently associated with CTS interest after adjusting for gender. CONCLUSIONS: Interest in CTS is disappointingly low among women and represents a troublesome disparity that must be addressed. Early exposure to CTS and more mentorship from cardiothoracic surgeons are critical to reverse the current trend. Further studies are necessary to determine factors limiting female exposure to CTS rotations and dissuading female applicants from pursuing careers in CTS.

Racial differences in attitudes to clinical pig organ Xenotransplantation.

INTRODUCTION: In addition to an organ donor shortage, racial disparities exist at different stages of the transplantation process. Xenotransplantation (XTx) could alleviate these issues. This study describes racial differences in attitudes to XTx among populations who may need a transplant or are transplant recipients. METHODS: A Likert-scale survey was distributed at outpatient clinics to parents of children with congenital heart disease (CHD) and kidney patients on their attitudes to pig organ XTx. Data from these two groups were stratified by race and compared. RESULTS: Ninety-seven parents of children with CHD (74.2% White and 25.8% Black) and 148 kidney patients (50% White and 50% Black) responded to our survey. Black kidney patients' acceptance of XTx although high (70%) was lower than White kidney patients (91%; P .003). White kidney patients were more likely to accept XTx if results are similar to allotransplantation (OR 4.14; 95% CI 4.51-11.41), and less likely to be concerned with psychosocial changes when compared to Black kidney patients (receiving a pig organ would change your personality OR 0.08; 95% CI 0.01-0.67 and would change social interaction OR 0.24; 95% CI 0.07-0.78). There were no racial differences in attitudes to XTx among parents of children with CHD. CONCLUSION: There are differences in attitudes to XTx particularly among Black kidney patients. Because kidneys may be the first organ for clinical trials of XTx, future studies that decrease scientific mistrust and XTx concerns among the Black community are needed to prevent disparities in uptake of possible future organ transplant alternatives.

Attitudes toward xenotransplantation: A survey of parents and pediatric cardiac providers.

BACKGROUND: Scientific advancements are occurring in cardiac xenotransplantation (XTx). However, there have been religious and social concerns surrounding this allotransplantation alternative. The purpose of this study was to explore the acceptance of XTx among stakeholders of the congenital heart disease (CHD) community. METHODS: A Likert-scale anonymous survey was distributed to physicians and nurses who care for children with CHD and parents of children with CHD. Psychosocial and clinical attitudes were compared across all groups to identify differences, and regression analysis was performed to identify factors associated with XTx acceptance. RESULTS: A total of 297 responded to the survey: 134 physicians, 62 nurses, and 101 parents. Potential acceptance of XTx if outcomes were similar to allotransplantation was high overall (75.3%), but different between the groups (physicians 86%; nurses 71%, parents 64%; P < .0001). Regression analysis showed respondents who reported religion would influence medical decision making (OR 0.48; 95%CI 0.24-0.97) and those who would not use a pig heart transplant as a bridge until a human heart became available were less likely to accept XTx (OR 0.09; 95%CI 0.04-0.21). Psychosocial concerns to XTx were minimal but were also associated with XTx acceptance particularly among parents (OR 0.17; 95%CI 0.03-0.80). CONCLUSIONS: Potential acceptance of XTx is high, assuming results are similar to allotransplantation. Religious beliefs and attitudes toward the use of XTx as a bridge to allotransplant may present barriers to XTx acceptance. Future research is needed to assess potential attitude differences in light of ethical, psychosocial, and religious objections to XTx.