The effect of excessive gas to blood ratios in an ECMO oxygenator.

INTRODUCTION: Oxygenators for paediatric Extracorporeal Membrane Oxygenation (ECMO) are required to operate over a wide range of flow rates, in a patient group ranging from neonates through to fully grown adolescents. ECMO oxygenators typically have a manufacturer's stated maximum gas: blood flow rate (GBFR) ratio of 2:1, however, many patients require greater ratios than this for adequate CO2 removal. Mismatches in GBFR in theory could result in high gas phase pressures. These increased pressures in theory could cause the formation of gross gaseous microemboli (GME) placing the child at higher risk of neurological injury. METHODS: We evaluated 6 paediatric and 6 adult A.L.ONE™ ECMO oxygenators and assessed their gas phase pressures and GME release, in an ex vivo setting, in GBFR ratios up to greater than 2, across a range of gas flow (1L - 10 L/min) rates with a fraction of inspired oxygen (FiO2) content of 50% and 100%. RESULTS: There were no increases above 10 mmHg observed in gas phase pressures in GBFR >= 2:1 in either adult or paediatric oxygenators. Laboratory examination of GME activity demonstrated a small increase in post-membrane GME release over the study period. GME release was unaffected by FiO2 setting or gas flow rate, with a maximum volume of < 6 µL in both paediatric and adult oxygenators. CONCLUSIONS: In an ex vivo setting, increasing GBFR above 2:1 in a paediatric oxygenator, and to a GBFR of 2:1 in an adult oxygenator did not significantly increase gas phase pressures, and no oxygenator membrane rupture was observed. There were no associations between gas flow rates and GME production.

Rapid desensitization through immunoadsorption during cardiopulmonary bypass. A novel method to facilitate human leukocyte antigen incompatible heart transplantation.

BACKGROUND: Anti-human leukocyte antigen (HLA)-antibody production represents a major barrier to heart transplantation, limiting recipient compatibility with potential donors and increasing the risk of complications with poor waiting-list outcomes. Currently there is no consensus to when desensitization should take place, and through what mechanism, meaning that sensitized patients must wait for a compatible donor for many months, if not years. We aimed to determine if intraoperative immunoadsorption could provide a potential desensitization methodology. METHODS: Anti-HLA antibody-containing whole blood was added to a Cardiopulmonary bypass (CPB) circuit set up to mimic a 20 kg patient undergoing heart transplantation. Plasma was separated and diverted to a standalone, secondary immunoadsorption system, with antibody-depleted plasma returned to the CPB circuit. Samples for anti-HLA antibody definition were taken at baseline, when combined with the CPB prime (on bypass), and then every 20 min for the duration of treatment (total 180 min). RESULTS: A reduction in individual allele median fluorescence intensity (MFI) to below clinically relevant levels (<1000 MFI), and in the majority of cases below the lower positive detection limit (<500 MFI), even in alleles with a baseline MFI >4000 was demonstrated. Reduction occurred in all cases within 120 min, demonstrating efficacy in a time period usual for heart transplantation. Flowcytometric crossmatching of suitable pseudo-donor lymphocytes demonstrated a change from T cell and B cell positive channel shifts to negative, demonstrating a reduction in binding capacity. CONCLUSIONS: Intraoperative immunoadsorption in an ex vivo setting demonstrates clinically relevant reductions in anti-HLA antibodies within the normal timeframe for heart transplantation. This method represents a potential desensitization technique that could enable sensitized children to accept a donor organ earlier, even in the presence of donor-specific anti-HLA antibodies.

Efficacy of outcome prediction of the respiratory ECMO survival prediction score and the predicting death for severe ARDS on VV-ECMO score for patients with acute respiratory distress syndrome on extracorporeal membrane oxygenation.

BACKGROUND: Extracorporeal Membrane Oxygenation (ECMO) therapy for respiratory failure is an increasingly popular modality of support. Patient selection is an important aspect of outcome success. This review assesses the efficacy of the popular prognostic tools Respiratory ECMO Survival Prediction Score (RESP) and Predicting Death for Severe ARDS on VV-ECMO score (PRESERVE) for ECMO patient selection. METHODS: A literature search was performed. Six publications were found to match the specified selection criteria. These publications were assessed and compared using the area under the receiver operating characteristic (AUROC) curve statistical method to ascertain the discriminatory ability of the models to predict treatment outcome. RESULTS: Six articles were included in this review from 306 screened, of which all were retrospective cohort studies. Data was generated over a period of 3-9 years from 13 referring hospitals. Studies consisted of 467 male and 221 female (30 unknown) participants in total with a high heterogeneity. The PRESERVE prognostic model was found to have a higher AUROC score than the RESP model, however both models were found to be sub-optimal in their discriminatory ability. A high chance of bias was seen across all included studies. CONCLUSION: It was the findings of this review, indicated by analysis using the AUROC measures, that the prognostic model PRESERVE performed better than RESP for predicting post ECMO therapy outcomes, for patients presenting with Acute Respiratory Distress Syndrome within their respective validated time frames, i.e., RESP at Intensive care unit (ICU) discharge and PRESERVE at 6 months post ICU discharge. However, It was recognized that comparator groups were small thereby introducing bias into the study. Further prospective, randomized studies would be necessary to effectively assess the utility of these predictive survival scores.

Lung transplantation in an 18-month-old with donor specific antibodies - The use of intraoperative, targeted plasma exchange.

BACKGROUND: Sensitised patients undergoing Human Leukocyte Antigen-incompatible transplantation are at increased risk of hyperacute rejection and may be predisposed to antibody-mediated rejection, chronic lung allograft dysfunction and higher mortality. CASE: We present a case of primary lung transplantation in the setting of late identification of donor specific antibodies treated with intraoperative target plasma exchange. The patient was treated with fresh human plasma to a final volume of 1.5 times the patient's systemic circulation. From a pre-transplant mean fluorescence intensity of 5002, donor-specific antibodies were undetectable following plasma exchange on single antigen bead assay. CONCLUSIONS: This method represents a potential desensitisation technique for use in the intraoperative period.

Machine Learning Approaches to Determine Feature Importance for Predicting Infant Autopsy Outcome.

INTRODUCTION: Sudden unexpected death in infancy (SUDI) represents the commonest presentation of postneonatal death. We explored whether machine learning could be used to derive data driven insights for prediction of infant autopsy outcome. METHODS: A paediatric autopsy database containing >7,000 cases, with >300 variables, was analysed by examination stage and autopsy outcome classified as 'explained (medical cause of death identified)' or 'unexplained'. Decision tree, random forest, and gradient boosting models were iteratively trained and evaluated. RESULTS: Data from 3,100 infant and young child (<2 years) autopsies were included. Naïve decision tree using external examination data had performance of 68% for predicting an explained death. Core data items were identified using model feature importance. The most effective model was XG Boost, with overall predictive performance of 80%, demonstrating age at death, and cardiovascular and respiratory histological findings as the most important variables associated with determining medical cause of death. CONCLUSION: This study demonstrates feasibility of using machine-learning to evaluate component importance of complex medical procedures (paediatric autopsy) and highlights value of collecting routine clinical data according to defined standards. This approach can be applied to a range of clinical and operational healthcare scenarios.

The Great Ormond Street Hospital immunoadsorption method for ABO-incompatible heart transplantation: a practical technique.

Traditionally, ABO-incompatible heart transplantation was accomplished using a plasma exchange technique to remove recipient plasma containing donor-incompatible anti-A/B isohaemagglutinins. However, this technique exposed patients to large volumes of allogeneic blood and blood products (up to three times the patient's circulating volume). In 2018, we published the first reported case of an ABO-incompatible heart transplant using an intraoperative immunoadsorption technique which minimises the exposure to blood products by specifically targeting anti-A/B isohaemagglutinins. We have subsequently used this technique in all children undergoing ABO-incompatible heart transplantation and become convinced of its efficacy in this population while observing no adverse effects. This article outlines the practical details required to perform the technique in order to avoid hyperacute rejection.

Beta-thalassemia in the paediatric cardiac surgery setting - a case report and literature review.

Beta (ß)-thalassemia is a blood disorder with an incidence of 1 in 100,000.1 This case report outlines a patient with ß-thalassemia requiring cardiopulmonary bypass (CPB) and the measures taken to ensure an uneventful procedure.

Oncotic pressure and paediatric cardiopulmonary bypass: establishing baseline data for complex congenital cardiac surgery and its relation to risk stratification.

OBJECTIVES: Colloid osmotic pressure (COP) is a major determinant of fluid shift in paediatric patients undergoing corrective surgery for congenital heart disease (CHD) using cardiopulmonary bypass (CPB). However, very few baseline data are available for those patients requiring surgery within the first few weeks and months of life. Our aim was to determine if our CHD population exhibited COP similar to that of other extremely ill subsets of patients and, if so, whether this related to risk stratification model scores. METHODS: Thirty consecutive patients under 10 kg underwent cardiac surgery with CPB. Data were collected on COP, albumin concentration, prime composition, post-operative length of ventilation and intensive care unit (ICU) stay as well as risk stratification utilising Risk Adjustment for Congenital Heart Surgery (RACHS-1) and Partial Risk Adjustment in Surgery (PRAiS) scoring systems. RESULTS: The patients had a mean pre-bypass COP of 13.9±2.5 mmHg. A significant negative correlation was observed between pre-operative baseline COP and length of ventilation (r=0.7; p<0.001) and a significant negative correlation between PRAiS (r=0.64; p<0.001) and RACHS-1 (r=0.5; p=0.004) scores and baseline COP was seen. CONCLUSIONS: Neonatal and paediatric patients requiring surgical correction of complex congenital cardiac malformations exhibit extremely low baseline COP, comparable to other sick neonatal populations, and are lower than those previously reported. Baseline COP correlates significantly with predicted survival rates and time spent on a ventilator.

Do lipid microemboli induce acute kidney injury during cardiopulmonary bypass?

BACKGROUND: Acute kidney injury (AKI) following cardiopulmonary bypass affects 5% of patients, representing significant postoperative morbidity and mortality. Animal models have shown an increased uptake of lipid microemboli (LME) into the renal vasculature, potentially indicating ischaemic causation. This study tested a new lipid filtration system (RemoweLL) against a conventional system with no lipid-depleting capacity to determine the efficacy of the filtration system and its effects on renal function. METHODS: Thirty consecutive patients underwent coronary artery bypass graft surgery using either the RemoweLL filtration system (15 patients) or a conventional cardiopulmonary bypass circuit (15 patients). Renal function was assessed using cystatin C concentrations as a surrogate marker of glomerular injury, as well as perioperative glomerular filtration rate (GFR) and serum creatinine concentrations. Patients were defined as having acute renal injury if there was an increase in absolute serum creatinine ⩾3 mg/dL (26.4 µmol/L) or 1.5-fold increase from baseline as categorised using the AKIN criteria. RESULTS: Postoperative differences in LME count between the two groups were highly significant [p<0.001]. Analysis of peak cystatin C concentrations showed significantly lower levels in the LME filtration group on the 2nd postoperative morning [p=0.04]. Two-factor ANOVA revealed a trend towards interaction, but this failed to reach significance [p=0.06]. There were no differences throughout the study period in serum creatinine or GFR [p>0.05]. There were no differences in any of the serum or urinary electrolytes. CONCLUSIONS: This study has shown a trend towards improved cystatin C removal with LME filtration; with significantly lower peak concentrations, although no further evidence of renoprotection could be demonstrated. Further research is warranted to establish possible renal benefits of LME filtration in patients undergoing cardiac surgery.

Leukocyte filtration of the cardiotomy suction. Does it affect systemic leukocyte activation or pulmonary function?

BACKGROUND: Cardiopulmonary bypass is thought to propagate a global systemic response through contact with the non-physiological surfaces of the extracorporeal circuit, leading to the stimulation of leukocytes, their adherence to endothelial cells and the release of cytotoxic molecules. This, in turn, has been shown to accelerate pulmonary injury. This study tested a new leukocyte-filtration system (RemoweLL) against a conventional system with no leukocyte-depleting capacity to determine the efficacy of the filtration system and its effects on pulmonary function. METHODS: Thirty patients underwent coronary artery bypass graft surgery using either the RemoweLL filtration system (15 patients) or a conventional cardiopulmonary bypass circuit (15 patients). Data were collected on the total number of leukocytes, their differentiation and activation, using the leukocyte adhesion integrin CD11b as a surrogate marker. Pulmonary function was assessed using the Alveolar-arterial Oxygenation Index (AaOI) and patients were categorized using the Berlin definition of acute respiratory distress syndrome (ARDS). RESULTS: Both groups showed significant increases in leukocyte numbers during CPB (p<0.001), with no differences noted between the groups. CD11b showed a significant increase in both groups, with peak activation occurring at the end of CPB, but no difference between the groups (p=0.8). There was a trend towards lower AaOI increases in the filtration group, but this did not reach significance (p=0.075) and there was no difference in ARDS definitions (p=0.33). CONCLUSIONS: Leukocyte filtration of cardiotomy suction did not influence total leukocyte counts or activation as measured by CD11b upregulation. Furthermore, no evidence could be found to suggest improved pulmonary function.

Long-term outcome after neonatal intervention for congenital critical aortic stenosis.

BACKGROUND: This study explored long-term outcome and functional status of patients born with critical aortic stenosis (CAS) following neonatal surgical or catheter interventions. METHODS: A 40-year retrospective review of all consecutive patients within a large, single-center referral unit who required neonatal (<30 days) intervention for CAS. Additional detailed evaluation of surviving patients >7 years age was performed, with clinical assessment, objective cardiopulmonary exercise testing and state-of-the-art characterization of myocardial function (advanced echocardiography and cardiac MRI). RESULTS: Between 1970 and 2010, ninety-six neonates underwent CAS intervention (mean age 9 ± 7.5 days). Early death occurred in 19 (19.8%) and late death in 10 patients. Overall survival at 10 and 30 years was 70.1% and 68.5%, freedom from reintervention was 41.8% and 32.9% respectively. Among the 25 long-term survivors available for detailed assessment (median age 15.7 ± 6.4 years), 55% exhibited impaired peak oxygen uptake. Mean left ventricle (LV) ejection fraction was 65 ± 11.2%, with a mean LV end-diastolic volume z-score of 0.02 ± 1.4. Mean LV outflow tract Vmax was 2.3 ± 1.02 m/s. CAS patients had reduced LV longitudinal and increased radial strain (p = 0.003, p < 0.001 respectively). Five patients had severe LV diastolic dysfunction associated with endocardial fibroelastosis (EFE) (p = 0.0014). CONCLUSION: Despite high early mortality rate, long-term survival of patients with CAS is reasonable at the expense of high reintervention rate. With successful intervention, there remained long-term clinical and subclinical LV myocardial impairment, of which EFE was one marker. Long-term follow-up of all CAS patients is crucial, involving detailed myocardial functional assessment to help elucidate physiology and optimise management.

One- and Two-Year Multidisciplinary Follow-Up of MIS-C at a Tertiary Hospital: A Retrospective Cohort Study.

BACKGROUND: Although 6-month follow-up of patients with multisystem inflammatory syndrome in children (MIS-C) was reassuring, there is scant data on long-term sequelae, including whether changing variants affect clinical severity and outcomes. METHODS: Children (<18 years of age) admitted to Great Ormond Street Hospital between April 4, 2020, and January 2023, meeting diagnostic criteria for MIS-C were included. Admission and follow-up data were categorized by the predominant SARS-CoV-2 circulating variant in the United Kingdom. RESULTS: One hundred and sixty children [median age, 10.1 (interquartile range, 7.9-12.6) years] were included. There was no difference in the time of symptom onset to diagnosis between waves (P=0.23) or hospitalization days across all waves (P=0.32). Inflammatory markers were normal for up to 2 years in all patients except one. Eleven patients (6.9%) remain in follow-up: cardiology (n=5), gastroenterology (n=5) and nephrology (n=1). The main self-reported symptoms at 2 years were abdominal pain (n=5) and myalgia (n=2). Fatigue was present in approximately a quarter of patients at admission; this reduced to 14 (9%), (2%) and 1 (2%) at 6-month, 1-year and 2-year follow-ups, respectively. Chronic fatigue or long-COVID symptomatology was rare (n=1) even with high rates of concurrent Epstein-Barr virus positivity (49/134). All patients had sustained neurological recovery with no new neurological pathology observed. CONCLUSIONS: Patients with MIS-C have a sustained recovery, which is reassuring for positive long-term outcomes. Across waves, time from symptom onset to diagnosis and treatment, symptomatology and length of stay were similar. Sustained recovery is reassuring for clinicians and parents alike. Differentiating long-COVID symptomatology from that of MIS-C is important in formulating an individualized treatment plan.

Oxygen delivery in pediatric cardiac surgery and its association with acute kidney injury using machine learning.

OBJECTIVE: Acute kidney injury (AKI) after pediatric cardiac surgery with cardiopulmonary bypass (CPB) is a frequently reported complication. In this study we aimed to determine the oxygen delivery indexed to body surface area (Do2i) threshold associated with postoperative AKI in pediatric patients during CPB, and whether it remains clinically important in the context of other known independent risk factors. METHODS: A single-institution, retrospective study, encompassing 396 pediatric patients, who underwent heart surgery between April 2019 and April 2021 was undertaken. Time spent below Do2i thresholds were compared to determine the critical value for all stages of AKI occurring within 48 hours of surgery. Do2i threshold was then included in a classification analysis with known risk factors including nephrotoxic drug usage, surgical complexity, intraoperative data, comorbidities and ventricular function data, and vasoactive inotrope requirement to determine Do2i predictive importance. RESULTS: Logistic regression models showed cumulative time spent below a Do2i value of 350 mL/min/m2 was associated with AKI. Random forest models, incorporating established risk factors, showed Do2i threshold still maintained predictive importance. Patients who developed post-CPB AKI were younger, had longer CPB and ischemic times, and required higher inotrope support postsurgery. CONCLUSIONS: The present data support previous findings that Do2i during CPB is an independent risk factor for AKI development in pediatric patients. Furthermore, the data support previous suggestions of a higher threshold value in children compared with that in adults and indicate that adjustments in Do2i management might reduce incidence of postoperative AKI in the pediatric cardiac surgery population.

Clinical phenotypes and outcomes in children with multisystem inflammatory syndrome across SARS-CoV-2 variant eras: a multinational study from the 4CE consortium.

Background: Multisystem inflammatory syndrome in children (MIS-C) is a severe complication of SARS-CoV-2 infection. It remains unclear how MIS-C phenotypes vary across SARS-CoV-2 variants. We aimed to investigate clinical characteristics and outcomes of MIS-C across SARS-CoV-2 eras. Methods: We performed a multicentre observational retrospective study including seven paediatric hospitals in four countries (France, Spain, U.K., and U.S.). All consecutive confirmed patients with MIS-C hospitalised between February 1st, 2020, and May 31st, 2022, were included. Electronic Health Records (EHR) data were used to calculate pooled risk differences (RD) and effect sizes (ES) at site level, using Alpha as reference. Meta-analysis was used to pool data across sites. Findings: Of 598 patients with MIS-C (61% male, 39% female; mean age 9.7 years [SD 4.5]), 383 (64%) were admitted in the Alpha era, 111 (19%) in the Delta era, and 104 (17%) in the Omicron era. Compared with patients admitted in the Alpha era, those admitted in the Delta era were younger (ES -1.18 years [95% CI -2.05, -0.32]), had fewer respiratory symptoms (RD -0.15 [95% CI -0.33, -0.04]), less frequent non-cardiogenic shock or systemic inflammatory response syndrome (SIRS) (RD -0.35 [95% CI -0.64, -0.07]), lower lymphocyte count (ES -0.16 × 109/uL [95% CI -0.30, -0.01]), lower C-reactive protein (ES -28.5 mg/L [95% CI -46.3, -10.7]), and lower troponin (ES -0.14 ng/mL [95% CI -0.26, -0.03]). Patients admitted in the Omicron versus Alpha eras were younger (ES -1.6 years [95% CI -2.5, -0.8]), had less frequent SIRS (RD -0.18 [95% CI -0.30, -0.05]), lower lymphocyte count (ES -0.39 × 109/uL [95% CI -0.52, -0.25]), lower troponin (ES -0.16 ng/mL [95% CI -0.30, -0.01]) and less frequently received anticoagulation therapy (RD -0.19 [95% CI -0.37, -0.04]). Length of hospitalization was shorter in the Delta versus Alpha eras (-1.3 days [95% CI -2.3, -0.4]). Interpretation: Our study suggested that MIS-C clinical phenotypes varied across SARS-CoV-2 eras, with patients in Delta and Omicron eras being younger and less sick. EHR data can be effectively leveraged to identify rare complications of pandemic diseases and their variation over time. Funding: None.

Classification Performance of Neural Networks Versus Logistic Regression Models: Evidence From Healthcare Practice.

Machine learning encompasses statistical approaches such as logistic regression (LR) through to more computationally complex models such as neural networks (NN). The aim of this study is to review current published evidence for performance from studies directly comparing logistic regression, and neural network classification approaches in medicine. A literature review was carried out to identify primary research studies which provided information regarding comparative area under the curve (AUC) values for the overall performance of both LR and NN for a defined clinical healthcare-related problem. Following an initial search, articles were reviewed to remove those that did not meet the criteria and performance metrics were extracted from the included articles. Teh initial search revealed 114 articles; 21 studies were included in the study. In 13/21 (62%) of cases, NN had a greater AUC compared to LR, but in most the difference was small and unlikely to be of clinical significance; (unweighted mean difference in AUC 0.03 (95% CI 0-0.06) in favour of NN versus LR. In the majority of cases examined across a range of clinical settings, LR models provide reasonable performance that is only marginally improved using more complex methods such as NN. In many circumstances, the use of a relatively simple LR model is likely to be adequate for real-world needs but in specific circumstances in which large amounts of data are available, and where even small increases in performance would provide significant management value, the application of advanced analytic tools such as NNs may be indicated.

International comparisons of laboratory values from the 4CE collaborative to predict COVID-19 mortality.

Given the growing number of prediction algorithms developed to predict COVID-19 mortality, we evaluated the transportability of a mortality prediction algorithm using a multi-national network of healthcare systems. We predicted COVID-19 mortality using baseline commonly measured laboratory values and standard demographic and clinical covariates across healthcare systems, countries, and continents. Specifically, we trained a Cox regression model with nine measured laboratory test values, standard demographics at admission, and comorbidity burden pre-admission. These models were compared at site, country, and continent level. Of the 39,969 hospitalized patients with COVID-19 (68.6% male), 5717 (14.3%) died. In the Cox model, age, albumin, AST, creatine, CRP, and white blood cell count are most predictive of mortality. The baseline covariates are more predictive of mortality during the early days of COVID-19 hospitalization. Models trained at healthcare systems with larger cohort size largely retain good transportability performance when porting to different sites. The combination of routine laboratory test values at admission along with basic demographic features can predict mortality in patients hospitalized with COVID-19. Importantly, this potentially deployable model differs from prior work by demonstrating not only consistent performance but also reliable transportability across healthcare systems in the US and Europe, highlighting the generalizability of this model and the overall approach.

Dealing with pericardial suction blood and residual pump volume: a review of current practices in the UK.

The pathological effects of pericardial suction blood (PSB) have been well described in numerous studies for many years; yet, despite this, there is no definitive answer to the question of how best to attenuate this pathology. More recently, large studies have shown that, whilst PSB contains many factors indicating its pathological potential, the direct re-infusion of PSB and residual pump volume (RPV) after cardiopulmonary bypass (CPB) potentially reduces the risk of transfusion and is no more harmful to the patient than the re-infusion of cell salvage-processed PSB after CPB.We conducted a telephone audit of UK perfusion units to determine if current protocols and practices reflected this.We found that there is a definite majority processing RPV with cell-saving devices, with many units defining their protocols as "surgeon dependent" whilst half immediately returned PSB to the systemic circulation whilst on CPB. The results of this national audit suggest that the issue of dealing with PSB and RPV is confused, heavily influenced by surgical and anaesthetic preference and lacking clear guidance and high quality evidence.

Cone reconstruction for Ebstein anomaly: Late biventricular function and possible remodeling.

OBJECTIVES: To evaluate late-term tricuspid valve competence and biventricular function following cone reconstruction for Ebstein anomaly, and to explore biventricular remodeling. METHODS: Consecutive adult and pediatric patients who underwent cone reconstruction from 2009 to 2019 were reviewed for inclusion in this retrospective cardiac magnetic resonance imaging study. Tricuspid valve competence was assessed with tricuspid regurgitation fraction. Biventricular systolic function was assessed by ejection fraction, cardiac index, indexed stroke volume, and indexed aortic and pulmonary artery beat volume. Biventricular remodeling was assessed by planimetered areas (right atrium, functional right ventricle, left heart), and indexed end-diastolic and end-systolic ventricular volumes. Paired t tests or Wilcoxon signed-rank tests were used for analyses. RESULTS: Of 58 included patients, 50 underwent cardiac magnetic resonance imaging. Twelve patients had both preoperative and late postoperative cardiac magnetic resonance imaging with a median follow-up of 5.11 years (interquartile range, 3.12-6.07 years). Focusing on these, tricuspid regurgitation fraction decreased (from 69% to 10%; P = .014), right ventricle ejection fraction remained stable, and antegrade pulmonary artery beat volume increased (from 26.7 to 41.6 mL/beat/m2; P = .037). The left ventricle stroke volume (from 30.4 to 44.1 mL/m2; P = .015) and antegrade aortic beat volume (from 28.5 to 41.1 mL/beat/m2; P = .014) also increased, and the left ventricle stroke volume improved progressively with time since surgery (P = .048). Whereas the right atrium area decreased (P = .004), the functional right ventricle and left heart area increased (cm2, P = .021 and P = .004). Right ventricle volumes showed a tendency to normalize and left ventricle indexed end-diastolic volume increased (from 50 to 69 mL/m2; P = .03) over time. CONCLUSIONS: Cone valve integrity was sustained. Biventricular function improved progressively during follow-up, and there are positive signs of biventricular remodeling late after cone reconstruction.

Intraoperative anti-A/B immunoadsorption is associated with significantly reduced blood product utilization with similar outcomes in pediatric ABO-incompatible heart transplantation.

BACKGROUND: Intraoperative anti-A/B immunoadsorption (ABO-IA) was recently introduced for ABO-incompatible heart transplantation. Here we report the first case series of patients transplanted with ABO-IA, and compare outcomes with those undergoing plasma exchange facilitated ABO-incompatible heart transplantation (ABO-PE). METHODS: Data were retrospectively analysed on all ABO-incompatible heart transplants undertaken at a single centre between January 1, 2000 and June 1, 2020. Data included all routine laboratory tests, demographics and pre-operative characteristics, intraoperative details and post-operative outcomes. Primary outcome measures were volume of blood product transfusions, maximum post-transplant isohaemagglutinin titres, occurrence of rejection and graft survival. Secondary outcome measures were length of intensive care and hospital stay. Demographic and survival data were also obtained for ABO-compatible transplants during the same time period for comparison. RESULTS: Thirty-seven patients underwent ABO-incompatible heart transplantation, with 27 (73%) using ABO-PE and 10 (27%) using ABO-IA. ABO-IA patients were significantly older than ABO-PE patients (p < 0.001) and the total volume of blood products transfused during the hospital admission was significantly lower (164 [126-212] ml/kg vs 323 [268-379] ml/kg, p < 0.001). No significant differences were noted between methods in either pre or post-transplant maximum isohaemagglutinin titres, incidence of rejection, length of intensive care or total hospital stay. Survival comparison showed no significant difference between antibody reduction methods, or indeed ABO-compatible transplants (p = 0.6). CONCLUSIONS: This novel technique appears to allow a significantly older population than typical to undergo ABO-incompatible heart transplantation, as well as significantly reducing blood product utilization. Furthermore, intraoperative anti-A/B immunoadsorption does not demonstrate increased early post-transplant isohaemagglutinin accumulation or rates of rejection compared to ABO-PE. Early survival is equivalent between ABO-IA, ABO-PE and ABO-compatible heart transplantation.