Single Ventricle Physiology Research Articles

Ex Vivo Modeling of Atrioventricular Valve Mechanics in Single Ventricle Physiology.

Single ventricle physiology (SVP) is used to describe any congenital heart lesion that is unable to support independent pulmonary and systemic circulations. Current treatment strategies rely on a series of palliation surgeries that culminate in the Fontan physiology, which relies on the single functioning ventricle to provide systemic circulation while passively routing venous return through the pulmonary circulation. Despite significant reductions in early mortality, the presence of atrioventricular valve (AVV) regurgitation is a key predictor of heart failure in these patients. We sought to evaluate the biomechanical changes associated with the AVV in SVP physiologies. Left and right ventricles were sutured onto patient-derived 3D-printed mounts and mounted into an ex vivo systemic heart simulator capable of reproducing Norwood, Glenn, Fontan and Late Fontan physiologies. We found that the tricuspid anterior leaflet experienced elevated maximum force, average force, and maximum yank compared to the posterior and septal leaflets. Between physiologies, maximum yank was greatest in the Norwood physiology relative to the Glenn, Fontan, and Late Fontan physiologies. These contrasting trends suggest that long- and short-term mechanics of AVV failure in single ventricle differ and that AVV interventions should account for asymmetries in force profiles between leaflets and physiologies.

Paediatric heart failure - understanding the pathophysiology and the current role of cardiac biomarkers in clinical practice.

Paediatric heart failure is a common clinical syndrome that may be experienced by children with congenital heart disease (CHD) and/or cardiomyopathy. It is characterised by clinical signs/symptoms which reflect the underlying pathophysiology based on one of three main clinical states: Pulmonary over-circulation, pressure overload, and ventricular failure. Current diagnosis relies on clinical assessment and echocardiogram imaging as cardiac biomarkers has been predominantly scientific to date. This review provides a comprehensive overview of paediatric heart failure pathophysiology and considers the available evidence for cardiac biomarkers in this setting. A literature review was completed using MEDLINE ALL, EMBASE, and PubMed on 10th November, 2022. Search terms included biomarkers, heart failure, heart defects, congenital heart disease, fontan circulation, single ventricle circulation, cardiomyopathy, and child. This allowed the identification of individual cardiac biomarkers which are the focus of this review. These included NT-proBNP, MR-proANP, MR-proADM, troponin, sST2, galectin 3, and growth differentiation factor-15. Paediatric studies have established reference ranges for NT-proBNP and troponin for children with structurally normal hearts. Of all the biomarkers reviewed, NT-proBNP appears to correlate most closely with symptoms of heart failure and ventricular dysfunction on echocardiogram. However, there remains limited longitudinal data for NT-proBNP, and no validated reference ranges for patients with CHD and/or cardiomyopathy. None of the other biomarkers reviewed were consistently superior to NT-proBNP. Further large paediatric studies of patients with heart failure are needed to validate NT-proBNP in CHD and to evaluate the role of novel biomarkers in specific types of CHD, e.g. single ventricle physiology.

Risk factors for long post-operative hospital stays after cardiopulmonary bypass surgery in full-term neonates.

Long hospital stays for neonates following cardiac surgery can be detrimental to short- and long-term outcomes. Furthermore, it can impact resource allocation within heart centres' daily operations. We aimed to explore multiple clinical variables and complications that can influence and predict the post-operative hospital length of stay. We conducted a retrospective observational review of the full-term neonates (<30 days old) who had cardiac surgery in a tertiary paediatric cardiac surgery centre - assessment of multiple clinical variables and their association with post-operative hospital length of stay. A total of 273 neonates were screened with a mortality rate of 8%. The survivors (number = 251) were analysed; 83% had at least one complication. The median post-operative hospital length of stay was 19.5 days (interquartile range 10.5, 31.6 days). The median post-operative hospital length of stay was significantly different among patients with complications (21.5 days, 10.5, 34.6 days) versus the no-complication group (14 days, 9.6, 19.5 days), p < 0.01. Among the non-modifiable variables, gastrostomy, tracheostomy, syndromes, and single ventricle physiology are significantly associated with longer post-operative hospital length of stay. Among the modifiable variables, deep vein thrombosis and cardiac arrest were associated with extended post-operative hospital length of stay. Complications following cardiac surgery can be associated with longer hospital stay. Some complications are modifiable. Deep vein thrombosis and cardiac arrest are among the complications that were associated with longer hospital stay and offer a direct opportunity for prevention which may be reflected in better outcomes and shorter hospital stay.

Analysis of anesthesia related severe adverse events in congenital catheterization cases from a single institution.

Analysis of anesthesia related severe adverse events in congenital catheterization cases from a single institution.

Univentricular hearts not undergoing Fontan: the type of palliation matters

Introduction and objectivesThere is scarce information on patients with single ventricle physiology (SVP) and restricted pulmonary flow not undergoing Fontan circulation. This study aimed to compare survival and cardiovascular events in these patients according to the type of palliation. MethodsSVP patient data were obtained from the databases of the adult congenital heart disease units of 7 centers. Patients completing Fontan circulation or developing Eisenmenger syndrome were excluded. Three groups were created according to the source of pulmonary flow: G1 (restrictive pulmonary forward flow), G2 (cavopulmonary shunt), and G3 (aortopulmonary shunts±cavopulmonary shunt). The primary endpoint was death. ResultsWe identified 120 patients. Mean age at the first visit was 32.2 years. Mean follow-up was 7.1 years. Fifty-five patients (45.8%) were assigned to G1, 30 (25%) to G2, and 35 (29.2%) to G3. Patients in G3 had worse renal function, functional class, and ejection fraction at the first visit and a more marked ejection fraction decline during follow-up, especially when compared with G1. Twenty-four patients (20%) died, 38 (31.7%) were admitted for heart failure, and 21 (17.5%) had atrial flutter/fibrillation during follow-up. These events were more frequent in G3 and significant differences were found compared with G1 in terms of death (HR, 2.9; 95%CI, 1.14-7.37; P=.026) and atrial flutter/fibrillation (HR, 2.9; 95%CI, 1.11-7.68; P=.037). ConclusionsThe type of palliation in patients with SVP and restricted pulmonary flow not undergoing Fontan palliation identifies distinct profiles. Patients palliated with aortopulmonary shunts have an overall worse prognosis with higher morbidity and mortality.

Palliation of a Heterotaxy Single Ventricle Neonate with Pulmonary Atresia and Obstructed TAPVR

Patients born with obstructed total anomalous pulmonary venous return have a high risk of morbidity and mortality in the neonatal period, which only increases when combined with single ventricle physiology and non-cardiac congenital anomalies such as heterotaxy syndrome. Despite advances in management of congenital heart disease, surgery within the first weeks of life to repair the pulmonary venous connection and establish pulmonary blood flow with a systemic-to-pulmonary shunt has historically led to disappointing outcomes. A multidisciplinary approach with pediatric interventional cardiology and cardiac surgery is required to reduce morbidity and mortality in this extremely high-risk patient population. Extending the time between birth and cardiac surgery can lessen postoperative complications and mortality risk, especially in patients with abnormal thoracoabdominal relationships. Our team was able to successfully utilize transcatheter stent placement in a vertical vein and patent ductus arteriosus to delay and stage cardiac surgeries in an infant born with obstructed total anomalous pulmonary venous return, unbalanced atrioventricular septal defect with pulmonary atresia and heterotaxy, thus reducing the morbidity and mortality associated with this diagnosis.

Total Anomalous Pulmonary Venous Connection: Surgical Outcomes and Risk Factors for Postoperative Pulmonary Vein Obstruction.

Total anomalous pulmonary venous connection (TAPVC) is a fatal congenital cardiac anomaly that requires urgent surgical intervention. The development of postoperative pulmonary vein obstruction (PVO) negatively impacts long-term survival. The present study aimed to evaluate the surgical outcomes of TAPVC repair and risk factors associated with postoperative PVO. Patients who underwent primary TAPVC repair at our institute between 2004 and 2022 were retrospectively enrolled, and those with right atrial isomerism and single ventricle physiology were excluded. Factors associated with survival and postoperative PVO were analyzed. A total of 116 patients were enrolled in the present study. The early mortality rate was 6.9%. Nineteen patients (16.4%) developed postoperative PVO within a median time of 59 days of the primary repair, of whom 10 were successfully relieved without any recurrent obstruction. In long-term follow-up, patients with postoperative PVO had significantly lower long-term survival rates than those without postoperative PVO [57.9%, 95% confidence interval (CI) = 34.8-79.5%; vs. 90.4%, 95% CI = 83-96.6% at 10 years, p < 0.001]. Risk factors for postoperative PVO development included lower body weight, younger age, preoperative mechanical ventilation, preoperative inotrope use, and emergency operation. Postoperative PVO was significantly associated with a higher long-term mortality rate after primary TAPVC repair, with the risk being higher in patients with critical preoperative status. The long-term outcome was good for patients in whom the obstruction was successfully relieved. Early detection and prompt intervention for postoperative PVO after TAPVC repair can improve overall survival in these patients.

Anaesthesia for Caesarean Section in a Patient with Large Ventricular Septal Defect with Pulmonary Hypertension with Single Ventricle Physiology

Pregnancy in a patient with large ventricular septal defect (VSD) with severe pulmonary hypertension (PAH) increases the risk of mortality severalfold. This when combined with single ventricle physiology forms a rare and deadly combination. A 26-year-old female presented for elective LSCS at 35 weeks gestation. She had a large VSD with severe PAH with a single ventricle physiology. We report the successful conduct of a caesarean section in this patient under graded epidural anaesthesia.

Current diagnostic and therapeutic strategies for the management of lymphatic insufficiency in patients with hypoplastic left heart syndrome.

Children with hypoplastic left heart syndrome share unique hemodynamic features that alter lymphatic integrity at all stages of palliation. Lymphatic congestion is almost universal in this patient group to some extent. It may lead to reversal of lymphatic flow, the development of abnormal lymphatic channels and ultimately decompression and loss of protein rich lymphatic fluid into extra lymphatic compartments in prone individuals. Some of the most devastating complications that are associated with single ventricle physiology, notably plastic bronchitis and protein losing enteropathy, have now been proven to be lymphatic in origin. Based on the new pathophysiologic concept new diagnostic and therapeutic strategies have recently been developed. Dynamic contrast magnetic resonance lymphangiography is now mainstay in diagnosis of lymphatic insufficiency and allows a thorough assessment of anatomy and function of the main lymphatic compartments through intranodal, intrahepatic and intramesenteric lymphatic imaging. Contrast enhanced ultrasound can evaluate thoracic duct patency and conventional fluoroscopic lymphangiography has been refined for evaluation of patients where magnetic resonance imaging cannot be performed. Novel lymphatic interventional techniques, such as thoracic duct embolization, selective lymphatic duct embolization and liver lymphatic embolization allow to seal abnormal lymphatic networks minimally invasive and have shown to resolve symptoms. Innominate vein turn-down procedures, whether surgical or interventional, have been designed to reduce lymphatic afterload and increase systemic preload effectively in the failing Fontan circulation. Outflow obstruction can now be managed with new microsurgical techniques that create lympho-venous anastomosis. Short term results for all of these new approaches are overall promising but evidence is sparse and long-term outcome still has to be defined. This review article aims to summarize current concepts of lymphatic flow disorders in single ventricle patients, discuss new emerging diagnostic and therapeutic strategies and point out lacks in evidence and needs for further research on this rapidly growing topic.

Rethinking status 1A criteria in pediatric cardiac transplantation: A case for the prioritization of patients with single ventricle anatomy supported by ventricular assist devices.

Over the past 2 years advancements in the techniques and technology of pediatric heart transplantation have exponentially increased. However, even as the number of pediatric donor hearts has grown, demand for this limited resource continues to far outpace supply. Thus, lifesaving support in the form of ventricular assist devices (VAD) has become increasingly utilized in bridging pediatric patients to cardiac transplant. In the current pediatric heart transplant listing criteria, adopted by the United Network for Organ Sharing (UNOS) in 2016, all pediatric patients with a VAD are granted 1A status and assigned top transplant priority regardless of their underlying pathology. However, should this be the case? We suggest that the presence of a VAD alone may not be sufficient for status 1A listing. In doing so, we specifically highlight the heightened acuity, resource utilization, risk profile, and diminished outcomes in patients with single ventricle physiology supported with VAD as compared to patients with structurally normal hearts who would both be listed under 1A status. Given this, from a distributive justice perspective, we further suggest that the lack of granularity in current pediatric cardiac transplant listing categories may inadvertently lead to an inequitable distribution of donor organs and hospital resources especially as it pertains to those with single ventricle anatomy on VAD support. We propose revisiting the current listing priorities in light of improved techniques, technology, and recent data to mitigate this phenomenon. By doing this, pediatric patients with single ventricle disease might be more equitably stratified while awaiting heart transplant.

Association of Early Postoperative Regional Oxygen Saturation Measures and Development of Necrotizing Enterocolitis in Neonates Following Cardiac Surgery.

Necrotizing enterocolitis (NEC) is a relatively common complication in neonates with single ventricle physiology following heart surgery. Near-infrared spectroscopy (NIRS) is used to measure regional oxygen saturations in neonates in the postoperative period. We sought to investigate the association of somatic regional oxygen saturation (srSO2) and cerebral regional oxygen saturation (crSO2) in the early postoperative period and the subsequent development of NEC. We performed a retrospective cohort study of neonates who underwent cardiac surgery with cardiopulmonary bypass from October 2017 to September 2021 at the University of Virginia Children's Hospital. Values of srSO2 and crSO2 were captured over the first 48h following surgery. 166 neonates were included and the median age at time of surgery was 8days. NEC was diagnosed in 18 neonates following heart surgery with a median interval from surgery to diagnosis of 7days. Neonates with single ventricle physiology had lower average crSO2 (62% vs 78%, p < 0.001), average srSO2 (72% vs 86%, p < 0.001), average crSO2 to srSO2 ratio (0.874 vs 0.913, p < 0.001), and an increased average srSO2-crSO2 difference (10% vs 8%, p = 0.03). Adjusting for single ventricle physiology, lower average crSO2 was associated with the development of definite NEC (modified Bell's criteria stage IIa and higher) (OR = 0.86, 95% CI 0.78-0.96, p = 0.007). Lower crSO2 values in the early postoperative period in neonates following cardiac surgery was associated with an increased risk in the subsequent development of NEC.

Narrative review of single ventricle: where are we after 40 years?

Key medical and surgical advances have been made in the longitudinal management of patients with "functionally" single ventricle physiology, with the principles of Fontan circulation applied to other complex congenital heart defects. The purpose of this article is to review all of the innovations, starting from fetal life, that led to a change of strategy for single ventricle. Our literature review included all full articles published in English language on the Cochrane, MedLine, and Embase with references to "single ventricle" and "univentricular hearts", including the initial history of the treatments for this congenital heart defects as well as the innovations reported within the last decades. All innovations introduced have been analyzed, including: (I) fetal diagnosis and interventions, in particular to prevent or reduce brain damages; (II) neonatal care; (III) post-natal diagnosis; (IV) interventional cardiology procedures; (V) surgical procedures, including neonatal palliations, hybrid procedures, bidirectional Glenn and variations, Fontan completion, biventricular repair; (VI) peri-operative management; (VII) Fontan failure, with Fontan take-down and conversion, and mechanical circulatory support; (VIII) transplantation, including heart, heart and lung, heart and liver; (IX) exercise; (X) pregnancy; (XI) adolescents and adults without Fontan completion; (XII) future studies, including experimental studies on animals, computational studies, genetics, stem cells and bioengineering. These last 40 years have certainly changed the course of natural history for children born with any form of "functionally" single ventricle, thanks to the improvement in diagnostic and treatment techniques, and particularly to the increased knowledge of the morphology and function of these complex hearts, from fetal to adult life. There is still much left unexplored and room for improvement, and all efforts should be concentrated in collaborations among different institutions and specialties, focused on the same matter.

Altered white matter connectivity in children with congenital heart disease with single ventricle physiology

Children born with congenital heart disease (CHD) have seen a dramatic decrease in mortality thanks to surgical innovations. However, there are numerous risk factors associated with CHD that can disrupt neurodevelopment. Recent studies have found that psychological deficits and structural brain abnormalities persist into adulthood. The goal of the current study was to investigate white matter connectivity in early school-age children (6–11 years), born with complex cyanotic CHD (single ventricle physiology), who have undergone Fontan palliation, compared to a group of heart-healthy, typically developing controls (TPC). Additionally, we investigated associations between white matter tract connectivity and measures on a comprehensive neuropsychological battery within each group. Our results suggest CHD patients exhibit widespread decreases in white matter connectivity, and the extent of these decreases is related to performance in several cognitive domains. Analysis of network topology showed that hub distribution was more extensive and bilateral in the TPC group. Our results are consistent with previous studies suggesting perinatal ischemia leads to white matter lesions and delayed maturation.

Pregnancy Outcomes in Women after the Fontan Procedure.

Women with single ventricle physiology after the Fontan procedure, despite numerous possible complications, can reach adulthood and give birth. Pregnancy poses a hemodynamic burden for distorted physiology of Fontan circulation, but according to the literature, it is usually well tolerated unless the patient is a "failing" Fontan. Our study aimed to assess maternal and fetal outcomes in patients after the Fontan procedure followed up in two tertiary Polish medical centers. We retrospectively evaluated all pregnancies in women after the Fontan procedure who were followed up between 1995-2022. During the study period, 15 women after the Fontan procedure had 26 pregnancies. Among 26 pregnancies, eleven ended with miscarriages, and 15 pregnancies resulted in 16 live births. Fetal complications were observed in 9 (56.3%) live births, with prematurity being the most common complication (n = 7, 43.8%). We recorded 3 (18.8%) neonatal deaths. Obstetrical complications were present in 6 (40%) out of 15 completed pregnancies-two (13.3%) cases of abruptio placentae, two (13.3%) pregnancies with premature rupture of membranes, and two (13.3%) patients with antepartum hemorrhage. There was neither maternal death nor heart failure decompensation during pregnancy. In two (13.3%) women, atrial arrhythmia developed. One (6.7%) patient in the second trimester developed ventricular arrhythmia. None of the patients suffered from systemic thromboembolism during pregnancy. Pregnancy in women after the Fontan procedure is well tolerated. However, it is burdened by a high risk of miscarriage and multiple obstetrical complications. These women require specialized care provided by both experienced cardiologists and obstetricians.

The convergent cavopulmonary connection: A novel and efficient configuration of Fontan to accommodate mechanical support

ObjectiveThe current total cavopulmonary connection Fontan has competing inflows and outflows, creating hemodynamic inefficiencies that contribute to Fontan failure and complicate placement and efficiency of mechanical circulatory support. We propose a novel convergent cavopulmonary connection (CCPC) Fontan design to create a single, converged venous outflow to the pulmonary arteries, thus increasing efficiency and mechanical circulatory support access. We then evaluate the feasibility and hemodynamic performance of the CCPC in various patient sizes using computational fluid dynamic assessments of computer-aided designs. MethodsCardiac magnetic resonance imaging data from 12 patients with single ventricle (10 total cavopulmonary connection, 2 Glenn) physiology (body surface area, 0.5-2.0 m2) were segmented to create 3-dimensional replicas of all thoracic structures. Surgically feasible CCPC shapes within constraints of anatomy were created using iterative computational fluid dynamic and clinician input. Designs varied based on superior and inferior vena cava conduit sizes, coronal attachment height, coronal entry angle, and axial entry angle of the superior vena cava to the inferior vena cava. CCPC designs were optimized based on efficiency (indexed power loss), risk of arteriovenous malformations (hepatic flow distribution), and risk of flow stasis (% nonphysiologic wall shear stress). ResultsAll CCPC designs met hemodynamic performance thresholds for indexed power loss and hepatic flow distribution. CCPC designs showed improvements in reducing % nonphysiologic wall shear stress and balancing HFD. ConclusionsCCPC is physiologically and surgically feasible in various patient sizes using validated computational fluid dynamic models. CCPC configuration has analogous indexed power loss, hepatic flow distribution, and % nonphysiologic wall shear stress compared with total cavopulmonary connection, and the single inflow and outflow may ease mechanical circulatory support therapies. Further studies are required for design optimization and mechanical circulatory support institution.

Analysis of Risk Factors and Outcomes of Fontan Procedure in Single Ventricular Repair: A Retrospective Observational Study

Introduction: The Fontan operation is a surgical technique used to treat cyanotic heart diseases with single ventricle physiology. Although it has undergone several modifications since its inception in 1971, it is still associated with significant morbidity and mortality. Aim: To examine the outcomes of the Fontan operation and identify various risk factors associated with it. Materials and Methods: This retrospective observational study was conducted at the Postgraduate Institute of Medical Education and Research (PGIMER) in Chandigarh, India from January 2014 to December 2017. All patients who underwent the Fontan operation at PGIMER were included in the study. The study analysed outcomes such as survival, arrhythmias, neurological complications, heart failure, cirrhosis, and Protein Losing Enteropathy (PLE) following the Fontan operation. Various risk factors that could potentially influence the outcome of the Fontan operation were assessed, including preoperative, intraoperative, and postoperative factors. Statistical analysis was performed using Statistical Package for the Social Sciences (SPSS) software, version 25.0. The Chi-square test was utilised to determine predictors of survival and other longterm outcomes, with a p-value of &lt;0.05 considered statistically significant. Results: A total of 35 patients underwent the Fontan operation during the study period and completed five years of follow-up. Out of these, 28 were known to be alive at the last contact. There were six early deaths (less than one year). The overall oneyear and five-year survival rates from the time of the operation were 29 (83%) and 28 (80%), respectively. Graft thrombosis/ thromboembolism was observed in three cases (8.6%) and neurological complications in three cases (8.6%) during the early postoperative period. Arrhythmias in 6 cases (14%) were the most common late postoperative complication. Conclusion: The Fontan procedure is currently the best available palliative treatment for cyanotic heart diseases with single ventricle physiology. Patient selection is crucial in this procedure, as the presence of risk factors may adversely affect the outcome.

Successful stenting of an obstructed Glenn anastomosis in a 20-month-old child

Children with univentricular heart disease may benefit from the Glenn operation (superior vena cava to right pulmonary artery anastomosis), one of the palliative treatment stages. Preoperative and postoperative variables like thrombosis, arrhythmias, and superior vena cava syndrome affect postoperative mortality. A 20-month-old child, known to have complex congenital heart disease with single ventricle physiology. She had Blalock–Taussig shunt in early infancy and then left Glenn anastomosis while she was recovering. Twenty-five days later, she developed acute thrombosis of her Glenn anastomosis. She was hemodynamically unstable with severe desaturation, and the decision was made for catheter-based intervention. Balloon dilatation of the thrombosis initially failed. However, relief of the blockade using 2 overlapping stents was successful and improved her pulmonary blood flow, avoiding urgent surgery for her. • The management of patients with single-ventricle physiology is complex and challenging. • Most patients undergoing BDG do well after the procedure. • One of the complications that may occur is thrombosis of the Glenn anastomosis, and it is a cause of significant morbidity and mortality.

165: ENTERAL NUTRITION ADEQUACY ON ECMO AND ITS ASSOCIATION WITH END-ORGAN FUNCTION

Introduction: Children with heart disease requiring ECMO support are at risk for nutritional deterioration. The provision of enteral nutrition (EN) is challenging due to several factors. We explored the relationship between EN adequacy and change in the pediatric sequential organ failure assessment (pSOFA) score in children with heart disease supported on ECMO. Methods: Children (≤21yo) with congenital or acquired heart disease requiring ECMO support between 1/1/2013 to 12/31/2020 at a single institution were included. Data was acquired from our electronic medical record, dietitian record and local ECMO and surgical databases. Change in pSOFA score was calculated with hemodynamic and laboratory values at the time of cannulation and decannulation. Adequacy was defined as total intake divided by goal intake as defined by the Schofield equation. Results: Two hundred and fifty-nine children were evaluated over an 8-year period; 54% (n=140) were male with a median age at admission of 5.3 [0, 33.6] months. Surgical admissions were more common (n=173) than medical. Most children had complex biventricular (n=102) and single ventricle (n=98) physiology. Admission weight-for-age Z-score (WAZ) was -0.9 [-2.3, -0.2] with a median change in WAZ during admission of -0.5 [-1.6, 0]. Venoarterial (VA) ECMO was nearly the universal mode of support (n=255) with a mean duration of support of 6.7 ± 12.3 days. Twenty-nine percent (n=74) of patients were provided EN while on ECMO. Median change in pSOFA score was 5 [0, 13]. Patients provided EN had a median change in pSOFA score of 4 [-0.3, 11] versus those who did not receive EN 6 [1, 13]; p=0.62. Median EN energy adequacy was 0 [0, 1] %. EN energy adequacy was not associated with change in pSOFA (p=0.37). Conclusions: EN provision on ECMO is not associated with worsening pSOFA scores. Despite the concerns that arise surrounding labile hemodynamics on ECMO, there is no evidence of worsening end organ function when provided EN. Energy adequacy on ECMO remains low and prohibits the ability to determine a significant association between adequacy and changes in end organ function. Further research is needed to determine the best ways to optimize EN adequacy knowing that there is no detriment to end organ function with its initiation.

303: SINGLE-VENTRICLE POSTOPERATIVE OUTCOMES BASED ON PARAMETRIC DATA

Introduction: The Bidirectional Glenn (BDG) operation is an important staging procedure for single ventricle physiology. Mortality rates after the BDG operation are low. Despite low mortality, the morbidity remains high and variable. Optimal physiologic targets in the postoperative period are yet known. This study aims to compare postoperative physiologic parameters after the BDG operation between patients with and without postoperative complications. Methods: This is a single-center retrospective cohort study of patients after the BDG operation. Data was collected from the medical records and Society of Thoracic Surgeons (STS) database. Postoperative data was acquired from Phillips Intellivue MX700 monitors. The target outcome was mortality or postoperative complication. Complications were labeled as medical, surgical, or both medical and surgical. Patient measurements were averaged hourly and then averaged hourly for the two groups. Student’s t-test (p< 0.001) was performed. Significant parameters were analyzed over 24 hour periods. Non-paired Student’s t-tests and Fisher’s exact tests (p< 0.05) were used for demographic and preoperative data. Results: Twenty-four patients underwent the BDG operation. Eight patients had no complications and 16 had postoperative complications. Four patients had only surgical complications and were excluded. There were no differences in characteristic, preoperative cardiac catheterization or echocardiographic data among the two groups. End-Tidal Carbon Dioxide was lower in patients with complications (33.1+/-2.7% vs 39.7+/-4.0%; p< 0.001); becoming different by 48 hours. Patients with complications had higher breaths per minute (BrPM) (33.4+/-4.14 BrPM vs 29.3+/-2.55 BrPM; p< 0.001). This difference was apparent by 48 hours. pH was higher in patients with complications (7.38+/-0.05 vs 7.33+/-0.07; p< 0.001) and became significant by 72 hours. Arterial carbon dioxide was lower in patients with complications (42.8+/-6.64mmHg vs. 53.6+/-10.42mmHg; p< 0.001), and became significant by 72 hours. Conclusions: This study demonstrates that physiologic data can serve as an early indicator for which postoperative BDG patients develop complications. Our data suggests that relative alkalosis with hypocarbia are associated with increased postoperative complications after BDG surgery.

327: NUTRITION IN NEONATAL AND PEDIATRIC EXTRACORPOREAL LIFE SUPPORT: A SURVEY OF CURRENT PRACTICES

Introduction: Adequate nutritional support is essential for children in the ICU. Malnourishment during critical illness is associated with increased morbidity and mortality, and improved enteral nutrition (EN) and protein intake are associated with decreased 60-day mortality. ICU patients with cardiac and/or respiratory failure who require ECMO are at increased risk due to high rates of protein catabolism and challenges in estimating energy requirements. These patients also have unclear metabolic needs and safety risks with both parenteral nutrition (PN) and EN. Assessing current national practices is crucial for standardized guideline development and recommendations. We aim to provide an update on current practices since a 2015 survey and hypothesized more respondents would report utilizing EN during ECMO with few differences between ICU physicians (MD/DOs) and registered dieticians (RDs). Methods: We distributed a survey via Qualtrics to 100 ECMO medical directors who had previously participated in survey-based research and those who requested participation during PediECMO presentations of this study. We also requested they forward the survey to their center RDs. Results: In total, 36 MD/DOs and 19 RDs responded. Respondents utilize PN more than EN (59%; 49%) at least half of the time. Respondents were more likely to start PN than EN during the first 24 hours (32%; 23%) but were equally likely to start PN and EN during the 24–48-hour window (34%; 32%). Respondents considered volume, calories, and protein to be the most critical nutritional goals with some variance in order between groups. Continuous feeds were preferred to bolus EN (70%; 17%). EN was preferred in respiratory distress syndrome and heart disease with biventricular physiology whereas PN was preferred for single ventricle physiology, ileus, and diaphragmatic hernia. Conclusions: Nutrition is a key component of reduction in morbidity and mortality; however, there is great variability in its delivery. Compared to 2015, EN is more commonly utilized than previously reported (49%; 24%) despite less protocol use (14%; 38%). These data support the need for development of a universal stepwise nutrition support algorithm to determine the safety of early EN versus PN as recommended by the ELSO Nutrition Guidelines published July 2022.