Reducing Hyperoxia Exposure in Infants Requiring Veno-Arterial Extracorporeal Membrane Oxygenation after Cardiac Surgery.

Recent studies have suggested worse outcomes in patients exposed to hyperoxia while supported on veno-arterial extracorporeal membrane oxygenation (VA-ECMO). However, there are no data regarding the effect of reducing hyperoxia exposure in this population by adjusting the fraction of inspired oxygen (FiO2) of the sweep gas of the ECMO circuit. A retrospective review of 143 patients less than 1 year of age requiring VA-ECMO following cardiac surgery from 2007 to 2018 was completed. 64 patients had a FiO2 of the sweep gas < 100% with an average PaO2 of 210 mm Hg in the first 48 h of support [vs 405 mm Hg in the group with a FiO2 = 100% (p < 0.0001)]. There was no difference in mortality at 30 days after surgery or other markers of end-organ injury with respect to whether the FiO2 was adjusted. At least one PaO2 value < 200 mm Hg in the first 24 h on ECMO in patients with a FiO2 < 100% trended toward a significant association (OR = 0.45, 95% CI = 0.21-1.01) with decreased risk of 30-day mortality when compared to those patients with a FiO2 = 100% and all PaO2 values > 200 mm Hg. Only 47% of patients with a FiO2 < 100% had an average PaO2 less than 200 mm Hg which indicates that the intervention of reducing the FiO2 of the sweep gas was not entirely effective at reducing hyperoxia exposure. Future research is needed for developing clinical protocols to avoid hyperoxia and to identify mechanisms for hyperoxia-induced injury on VA-ECMO.

Methods to Enhance Causal Inference for Assessing Impact of Clinical Informatics Platform Implementation.

BACKGROUND: Hospitals are increasingly likely to implement clinical informatics tools to improve quality of care, necessitating rigorous approaches to evaluate effectiveness. We leveraged a multi-institutional data repository and applied causal inference methods to assess implementation of a commercial data visualization software in our pediatric cardiac intensive care unit. METHODS: Natural experiment in the University of Michigan (UM) Cardiac Intensive Care Unit pre and postimplementation of data visualization software analyzed within the Pediatric Cardiac Critical Care Consortium clinical registry; we identified N=21 control hospitals that contributed contemporaneous registry data during the study period. We used the platform during multiple daily rounds to visualize clinical data trends. We evaluated outcomes-case-mix adjusted postoperative mortality, cardiac arrest and unplanned readmission rates, and postoperative length of stay-most likely impacted by this change. There were no quality improvement initiatives focused specifically on these outcomes nor any organizational changes at UM in either era. We performed a difference-in-differences analysis to compare changes in UM outcomes to those at control hospitals across the pre versus postimplementation eras. RESULTS: We compared 1436 pre versus 779 postimplementation admissions at UM to 19 854 (pre) versus 14 160 (post) at controls. Admission characteristics were similar between eras. Postimplementation at UM we observed relative reductions in cardiac arrests among medical admissions, unplanned readmissions, and postoperative length of stay by -14%, -41%, and -18%, respectively. The difference-in-differences estimate for each outcome was statistically significant (P<0.05), suggesting the difference in outcomes at UM pre versus postimplementation is statistically significantly different from control hospitals during the same time. CONCLUSIONS: Clinical registries provide opportunities to thoroughly evaluate implementation of new informatics tools at single institutions. Borrowing strength from multi-institutional data and drawing ideas from causal inference, our analysis solidified greater belief in the effectiveness of this software across our institution.

Nicorandil attenuates ventricular dysfunction and organ injury after cardiopulmonary bypass.

BACKGROUND: Nicorandil, an adenosine triphosphate-sensitive potassium channel agonist and nitric oxide donor, is a coronary vasodilator used to treat ischemia-induced chest pain, but it's potential cardioprotective benefits during open heart surgery have not been thoroughly investigated. The study objective was to assess the impact of nicorandil on postoperative ventricular dysfunction and end-organ injury in an established experimental model of open-heart surgery with cardiopulmonary bypass (CPB) and cardioplegic arrest. We hypothesized that nicorandil would attenuate myocardial ischemia-reperfusion (IR) injury, preserve ventricular function, and reduce end-organ injury. METHODS: Rabbits were cannulated for CPB, followed by 60 min of aortic cross-clamp (ACC) with cold cardioplegic arrest, and 120 min of recovery after ACC removal. Nicorandil (or normal saline vehicle) was given intravenously 5 min before ACC and continued throughout the recovery period. Left ventricular developed pressure (LVDP), systolic contractility (LV + dP/dt), and diastolic relaxation (LV -dP/dt) were continuously recorded, and blood and tissue samples were collected for measurement of oxidant stress (OS), inflammation, apoptosis, and organ injury. RESULTS: Nicorandil significantly attenuated IR-induced LV dysfunction compared to saline control (R-120: LV + dP/dt: 1596 ± 397 vs. 514 ± 269 mmHg/s, p = 0.010; LV -dP/dt: -1524 ± 432 vs. -432 ± 243 mmHg/s, p < 0.001; LVDP: 55 ± 11 vs. 22 ± 5 mmHg, p = 0.046). Furthermore, nicorandil inhibited IR-induced increases in OS, inflammation, apoptosis, and organ injury. CONCLUSIONS: Nicorandil exhibits myocardial protection by attenuation of IR-induced LV dysfunction associated with OS, inflammation, apoptosis, and organ injury. Nicorandil should be explored further as a potential therapeutic strategy for limiting global IR injury during open-heart surgery in humans.

Prediction of extubation failure in the paediatric cardiac ICU using machine learning and high-frequency physiologic data.

BACKGROUND: Cardiac intensivists frequently assess patient readiness to wean off mechanical ventilation with an extubation readiness trial despite it being no more effective than clinician judgement alone. We evaluated the utility of high-frequency physiologic data and machine learning for improving the prediction of extubation failure in children with cardiovascular disease. METHODS: This was a retrospective analysis of clinical registry data and streamed physiologic extubation readiness trial data from one paediatric cardiac ICU (12/2016-3/2018). We analysed patients' final extubation readiness trial. Machine learning methods (classification and regression tree, Boosting, Random Forest) were performed using clinical/demographic data, physiologic data, and both datasets. Extubation failure was defined as reintubation within 48 hrs. Classifier performance was assessed on prediction accuracy and area under the receiver operating characteristic curve. RESULTS: Of 178 episodes, 11.2% (N = 20) failed extubation. Using clinical/demographic data, our machine learning methods identified variables such as age, weight, height, and ventilation duration as being important in predicting extubation failure. Best classifier performance with this data was Boosting (prediction accuracy: 0.88; area under the receiver operating characteristic curve: 0.74). Using physiologic data, our machine learning methods found oxygen saturation extremes and descriptors of dynamic compliance, central venous pressure, and heart/respiratory rate to be of importance. The best classifier in this setting was Random Forest (prediction accuracy: 0.89; area under the receiver operating characteristic curve: 0.75). Combining both datasets produced classifiers highlighting the importance of physiologic variables in determining extubation failure, though predictive performance was not improved. CONCLUSION: Physiologic variables not routinely scrutinised during extubation readiness trials were identified as potential extubation failure predictors. Larger analyses are necessary to investigate whether these markers can improve clinical decision-making.

Impact of Protein-Losing Enteropathy on Inflammatory Biomarkers and Vascular Dysfunction in Fontan Circulation.

Fontan palliation has improved survival for single ventricle patients, but long-term complications persist including cardiovascular dysfunction, neurohormonal abnormalities, and protein-losing enteropathy (PLE). Although chronic inflammation contributes to morbidity, an association between inflammation and vascular dysfunction has not been studied. We assessed inflammation and vascular function in 31 Fontan-palliated patients (52% male, median age 14.3 years), including 10 PLE+. Fontan circulation was associated with altered inflammatory cytokines (TNF-α: mean 2.5 ± 1.4 vs. 0.7 ± 0.2 pg/ml, p < 0.0001; sTNFR2: 371 ± 108 vs. 2694 ± 884 pg/ml, p < 0.0001) and vascular dysfunction [log-transformed reactive hyperemia index (lnRHI) 0.28 ± 0.19 vs. 0.47 ± 0.26, p < 0.01; augmentation index (AI) -2.9 ± 13.8 vs. -16.3 ± 12.0, p = 0.001; circulating endothelial progenitor cells (cEPCs) 5.0 ± 8.1 vs. 22.8 ± 15.9, p = 0.0002)]. Furthermore, PLE+ patients showed greater inflammation (IFN-γ 6.3 ± 2.2 vs. 11.5 ± 7.9 pg/ml, p = 0.01; sTNFR1: 1181 ± 420 vs. 771 ± 350 pg/ml, p = 0.01) and decreased arterial compliance (AI: 5.4 ± 17.1 vs. -6.8 ± 10.2, p = 0.02) than PLE- patients. Circulating EPCs, but not inflammatory cytokines, were inversely associated with arterial stiffness in Fontan patients. In conclusion, chronic inflammation and vascular dysfunction are observed after Fontan operation, with greater inflammation and arterial stiffness in Fontan patients with active PLE. However, there is no clear association between inflammatory cytokines and vascular dysfunction, suggesting these pathophysiologic processes are not mechanistically linked.

Normoxic re-oxygenation ameliorates end-organ injury after cardiopulmonary bypass.

BACKGROUND: In a rabbit model of cardiopulmonary bypass (CPB) and cardioplegic arrest, we previously showed that hyperoxic myocardial reperfusion was associated with increased left ventricular (LV) systolic dysfunction and myocardial injury compared with normoxic reperfusion. The aim of this study was to evaluate in our experimental model the impact of post-CPB reperfusion conditions on other organs potentially vulnerable to ischemic injury such as the brain and kidney. METHODS: After 60 min of CPB, aortic cross-clamp, and cold cardioplegic arrest, rabbits were reperfused under hyperoxic or normoxic conditions for 120 min. Left ventricular systolic contractility (LV + dP/dt) and diastolic relaxation (LV -dP/dt) were continuously recorded, and end-organ injury was assessed by measuring circulating biomarkers specific for kidney (cystatin C and creatinine) and brain injury [S100B and neuron specific enolase (NSE)]. At completion of the protocol, kidney and brain tissues were harvested for measuring oxidant stress (OS), inflammation and apoptosis. RESULTS: Following aortic cross-clamp removal, rabbits exposed to normoxic reperfusion demonstrated preserved LV systolic and diastolic function compared with hyperoxic reperfusion (LV + dP/dt: 70 ± 14% of pre-CPB vs. 36 ± 21%, p = 0.018; LV -dP/dt: 72 ± 36% of pre-CPB vs. 33 ± 20%, p = 0.023). Similarly, CPB increased plasma creatinine, S100B and NSE that were significantly attenuated by normoxic reperfusion compared with hyperoxic reperfusion (creatinine: 4.0 ± 0.5 vs. 7.1 ± 0.8 mg/dL, p = 0.004; S100B: 4.0 ± 0.8 vs. 6.7 ± 1.0 ng/mL, p = 0.047; NSE: 57.7 ± 6.8 vs. 101.3 ± 16.1 pg/mL, p = 0.040). Furthermore, both kidney and brain tissues showed increased mRNA expression and activation of pathways for OS, inflammation, and apoptosis, that were reduced under normoxic compared with hyperoxic conditions. CONCLUSIONS: Normoxic reperfusion ameliorates cardiac, renal and neural injury compared with hyperoxic reperfusion in an in vivo animal model of CPB and cardioplegic arrest. This protective effect of normoxic reperfusion may be due to a reduction in signaling pathways for OS, inflammation, and apoptosis.

Improvement in Pediatric Cardiac Surgical Outcomes Through Interhospital Collaboration.

BACKGROUND: Patients undergoing complex pediatric cardiac surgery remain at considerable risk of mortality and morbidity, and variation in outcomes exists across hospitals. The Pediatric Cardiac Critical Care Consortium (PC4) was formed to improve the quality of care for these patients through transparent data sharing and collaborative learning between participants. OBJECTIVES: The purpose of this study was to determine whether outcomes improved over time within PC4. METHODS: The study analyzed 19,600 hospitalizations (18 hospitals) in the PC4 clinical registry that included cardiovascular surgery from August 2014 to June 2018. The primary exposure was 2 years of PC4 participation; this provided adequate time for hospitals to accrue data and engage in collaborative learning. Aggregate case mix-adjusted outcomes were compared between the first 2 years of participation (baseline) and all months post-exposure. We also evaluated outcomes from the same era in a cohort of similar, non-PC4 hospitals. RESULTS: During the baseline period, there was no evidence of improvement. We observed significant improvement in the post-exposure period versus baseline for post-operative intensive care unit mortality (2.1% vs. 2.7%; 22% relative reduction [RR]; p = 0.001), in-hospital mortality (2.5% vs. 3.3%; 24% RR; p = 0.001), major complications (10.1% vs. 11.5%; 12% RR; p < 0.001), intensive care unit length of stay (7.3 days vs. 7.7 days; 5% RR; p < 0.001), and duration of ventilation (61.3 h vs. 70.6 h; 13% RR; p = 0.01). Non-PC4 hospitals showed no significant improvement in mortality, complications, or hospital length of stay. CONCLUSIONS: This analysis demonstrates improving cardiac surgical outcomes at children's hospitals participating in PC4. This change appears unrelated to secular improvement trends, and likely reflects PC4's commitment to transparency and collaboration.

Differential Effects of Normoxic and Hyperoxic Reperfusion on Global Myocardial Ischemia-Reperfusion Injury.

The objectives were to investigate if after hypoxia or ischemia, normoxic reperfusion is associated with less oxidant stress (OS), inflammation, and myocardial injury than hyperoxic reperfusion. In this study, cardiomyocytes (H9c2 cells) were cultured in hypoxia, followed by reoxygenation in normoxia or hyperoxia. Cardiomyocyte OS, inflammation, and apoptosis were measured. In parallel experiments, rabbits were cannulated for cardiopulmonary bypass (CPB). Following cardioplegic arrest and aortic cross-clamp removal, hearts were reperfused under normoxic or hyperoxic conditions. Left ventricular developed pressure and contractility (LV +dP/dt) were recorded, and blood samples and heart tissues were collected for measurement of OS, inflammation, and cardiac injury. Results showed that H9c2 cells exposed to hyperoxic reoxygenation showed significant increases in OS, inflammation, and apoptosis compared to normoxic reoxygenation. Following CPB and 2-hour hyperoxic reperfusion, LV +dP/dt and left ventricular developed pressure were significantly decreased compared with pre-CPB values (to 36 ± 21%, P = 0.002; and 53 ± 20%, P = 0.02, respectively), associated with significant increases in all plasma and tissue biomarkers for OS, inflammation, and myocardial injury. In contrast, LV +dP/dt was relatively well preserved under normoxic reperfusion conditions (to 70 ± 14% after 2-hour reperfusion), and was associated with an attenuated myocardial OS, inflammatory, apoptotic, and injury response compared to the hyperoxia group (eg, cTn-I: 5.9 ± 1.5 vs 20.2 ± 7.6 ng/mL, respectively, P < 0.0001). Overall, in both in vitro and in vivo experiments, normoxic reperfusion/reoxygenation was associated with less robust OS, inflammation, apoptosis, and myocardial injury compared with hyperoxic reperfusion/reoxygenation. These results suggest that hyperoxia should be avoided to minimize myocardial OS, inflammation, and ventricular dysfunction after CPB.

Cardiac Networks United: an integrated paediatric and congenital cardiovascular research and improvement network.

Optimising short- and long-term outcomes for children and patients with CHD depends on continued scientific discovery and translation to clinical improvements in a coordinated effort by multiple stakeholders. Several challenges remain for clinicians, researchers, administrators, patients, and families seeking continuous scientific and clinical advancements in the field. We describe a new integrated research and improvement network - Cardiac Networks United - that seeks to build upon the experience and success achieved to-date to create a new infrastructure for research and quality improvement that will serve the needs of the paediatric and congenital heart community in the future. Existing gaps in data integration and barriers to improvement are described, along with the mission and vision, organisational structure, and early objectives of Cardiac Networks United. Finally, representatives of key stakeholder groups - heart centre executives, research leaders, learning health system experts, and parent advocates - offer their perspectives on the need for this new collaborative effort.

Severe Acute Kidney Injury Following Stage 1 Norwood Palliation: Effect on Outcomes and Risk of Severe Acute Kidney Injury at Subsequent Surgical Stages.

OBJECTIVES: To identify associations of severe acute kidney injury early after stage 1 (Norwood) operation with risk of severe acute kidney injury and comorbidities at subsequent palliative stages in patients with hypoplastic left heart syndrome and other single ventricle lesions with left-sided obstruction. DESIGN: Retrospective cohort study. Severe acute kidney injury defined as Kidney Disease Improving Global Outcomes stage 3. SETTING: Single pediatric cardiac center. PATIENTS: Infants less than or equal to 28 days old with single ventricle physiology and left-sided obstruction undergoing stage 1 operation between September 2007 and November 2012 (n = 136). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The occurrence rate of severe acute kidney injury was 21% (28/136) following stage 1, 12% (12/98) following stage 2 palliation (superior cavo-pulmonary anastomosis), and 10% (7/73) following stage 3 palliation (total cavo-pulmonary anastomosis). Severe acute kidney injury early after stage 1 operation was significantly associated with continuous intravenous loop diuretic infusion, need for extracorporeal membrane oxygenation, and in-hospital death (all p < 0.05). Gestational age at birth was associated with severe acute kidney injury at stage 2 (p = 0.04) and stage 3 (p = 0.01). Severe acute kidney injury at stage 1 was an independent risk factor for severe acute kidney injury at stage 2 (adjusted odds ratio, 4.3; 95% CI, 1.1-16.9; p = 0.04). Development of severe acute kidney injury after stage 1 was associated with longer mechanical ventilation time after stage 3 (p = 0.047). CONCLUSIONS: Severe acute kidney injury after stage 1 palliation was an independent risk factor for developing severe acute kidney injury at stage 2, and was associated with prolonged duration of mechanical ventilation following stage 3. Information on the incidence and associated risk factors for postoperative acute kidney injury in hypoplastic left heart syndrome patients from multiple congenital heart centers is a necessary next step to further understand the long-term burden of severe acute kidney injury after staged palliation.

Design and initial results of a programme for routine standardised longitudinal follow-up after congenital heart surgery.

BACKGROUND: With improvements in early survival following congenital heart surgery, it has become increasingly important to understand longer-term outcomes; however, routine collection of these data is challenging and remains very limited. We describe the development and initial results of a collaborative programme incorporating standardised longitudinal follow-up into usual care at the Children's Hospital of Philadelphia (CHOP) and University of Michigan (UM). METHODS: We included children undergoing benchmark operations of the Society of Thoracic Surgeons. Considerations regarding personnel, patient/parent engagement, funding, regulatory issues, and annual data collection are described, and initial follow-up rates are reported. RESULTS: The present analysis included 1737 eligible patients undergoing surgery at CHOP from January 2007 to December 2014 and 887 UM patients from January 2010 to December 2014. Overall, follow-up data, of any type, were obtained from 90.8% of patients at CHOP (median follow-up 4.3 years, 92.2% survival) and 98.3% at UM (median follow-up 2.8 years, 92.7% survival), with similar rates across operations and institutions. Most patients lost to follow-up at CHOP had undergone surgery before 2010. Standardised questionnaires assessing burden of disease/quality of life were completed by 80.2% (CHOP) and 78.4% (UM) via phone follow-up. In subsequent pilot testing of an automated e-mail system, 53.4% of eligible patients completed the follow-up questionnaire through this system. CONCLUSIONS: Standardised follow-up data can be obtained on the majority of children undergoing benchmark operations. Ongoing efforts to support automated electronic systems and integration with registry data may reduce resource needs, facilitate expansion across centres, and support multi-centre efforts to understand and improve long-term outcomes in this population.

Perceptions of 24/7 In-house Attending Coverage on Fellow Education and Autonomy in a Pediatric Cardiothoracic Intensive Care Unit.

BACKGROUND: The 24/7 in-house attending coverage is emerging as the standard of care in intensive care units. Implementation costs, workforce feasibility, and patient outcomes resulting from changes in physician staffing are widely debated topics. Understanding the impact of staffing models on the learning environment for medical trainees and faculty is equally warranted, particularly with respect to trainee education and autonomy. OBJECTIVE: This study aims to elicit the perceptions of pediatric cardiology fellows and attendings toward 24/7 in-house attending coverage and its effect on fellow education and autonomy. METHODS: We surveyed pediatric cardiology fellows and attendings practicing in the pediatric cardiothoracic intensive care unit (PCTU) of a large, university-affiliated medical center, using structured Likert response items and open-ended questions, prior to and following the transition to 24/7 in-house attending coverage. RESULTS: All (100%) trainees and faculty completed all surveys. Both prior to and following transition to 24/7 in-house attending coverage, all fellows, and the majority of attendings agreed that the overnight call experience benefited fellow education. At baseline, trainees identified limited circumstances in which on-site attending coverage would be critical. Preimplementation concerns that 24/7 in-house attending coverage would negatively affect the education of fellows were not reflected following actual implementation of the new staffing policy. However, based upon open-ended questions, fellow autonomy was affected by the new paradigm, with fellows and attendings reporting decreased "appropriateness" of autonomy after implementation. CONCLUSIONS: Our prospective study, showing initial concerns about limiting the learning environment in transitioning to 24/7 in-house attending coverage did not result in diminished perceptions of the educational experience for our fellows but revealed an expected decrease in fellow autonomy. The study indirectly facilitated open discussions about methods to preserve fellow education and warranted autonomy in our PCTU; however, continued efforts are needed to achieve the optimal balance between supervised training and the transition to autonomous practice.

Collaborative quality improvement in the cardiac intensive care unit: development of the Paediatric Cardiac Critical Care Consortium (PC4).

Despite many advances in recent years for patients with critical paediatric and congenital cardiac disease, significant variation in outcomes remains across hospitals. Collaborative quality improvement has enhanced the quality and value of health care across specialties, partly by determining the reasons for variation and targeting strategies to reduce it. Developing an infrastructure for collaborative quality improvement in paediatric cardiac critical care holds promise for developing benchmarks of quality, to reduce preventable mortality and morbidity, optimise the long-term health of patients with critical congenital cardiovascular disease, and reduce unnecessary resource utilisation in the cardiac intensive care unit environment. The Pediatric Cardiac Critical Care Consortium (PC4) has been modelled after successful collaborative quality improvement initiatives, and is positioned to provide the data platform necessary to realise these objectives. We describe the development of PC4 including the philosophical, organisational, and infrastructural components that will facilitate collaborative quality improvement in paediatric cardiac critical care.

Splanchnic near-infrared spectroscopy and risk of necrotizing enterocolitis after neonatal heart surgery.

Infants with critical congenital heart disease, especially patients with a single-ventricle (SV) physiology, are at increased risk for the development of necrotizing enterocolitis (NEC). Decreased splanchnic oxygen delivery may contribute to the development of NEC and may be detected by regional oximetry (rSO2) via splanchnic near-infrared spectroscopy (NIRS). This prospective study enrolled 64 neonates undergoing biventricular (BV) repair or SV palliation for CHD and monitored postoperative splanchnic rSO2 before and during initiation of enteral feedings to determine whether changes in rSO2 are associated with risk of NEC. Suspected or proven NEC was observed in 32 % (11/34) of the SV subjects and 0 % (0/30) of the BV subjects (p = 0.001). Compared with the BV subjects, the SV palliated subjects had significantly lower splanchnic rSO2 before and during initiation of enteral feedings, but the groups showed no difference after correction for lower pulse oximetry (SpO2) in the SV group. The clinical parameters were similar among the SV subjects with and without NEC except for cardiopulmonary bypass times, which were longer for the patients who experienced NEC (126 vs 85 min; p = 0.03). No difference was observed in splanchnic rSO2 or in the SpO2-rSO2 difference between the SV subjects with and without NEC. Compared with the patients who had suspected or no NEC, the subjects with proven NEC had a lower average splanchnic rSO2 (32.6 vs 47.0 %; p = 0.05), more time with rSO2 less than 30 % (48.8 vs 6.7 %; p = 0.04) at one-fourth-volume feeds, and more time with SpO2-rSO2 exceeding 50 % (33.3 vs 0 %; p = 0.03) before feeds were initiated. These data suggest that splanchnic NIRS may be a useful tool for assessing risk of NEC, especially in patients with an SV physiology.

Timing of neonatal cardiac surgery is not associated with perioperative outcomes.

OBJECTIVE: The optimal timing for neonatal cardiac surgery is unknown. We aimed to determine the relationship between age at surgery and perioperative outcomes, hypothesizing that earlier intervention would be associated with lower morbidity and mortality. METHODS: A retrospective review was performed of neonates who had undergone an arterial switch operation, stage 1 palliation for functional single ventricle, or systemic-to-pulmonary shunt for obstructed pulmonary blood flow from January 1, 2005, to December 31, 2010. The subjects with clinical indications for delayed surgery or prematurity were excluded. Age at surgery was evaluated as both a continuous and a categorical variable. The primary outcome was a composite endpoint of mortality or prolonged intensive care stay. RESULTS: Of 344 subjects, 286 (77 arterial switch operation, 124 stage 1 palliation, 85 systemic-to-pulmonary shunt) met the inclusion criteria. In each group, age at surgery was not associated with the primary composite endpoint. The patients who died after systemic-to-pulmonary shunt had a median age at surgery of 3 days versus 6 days for the survivors (P = .04). A similar, but nonsignificant, pattern was seen for patients undergoing arterial switch operations (4.5 vs 7 days; P = .09). Earlier surgery was not associated with a reduced duration of vasoactive support, mechanical ventilation, or intensive care unit length of stay in any group. Stage 1 palliation subjects in the upper age quartile (≥8 days) at surgery were less likely to require prolonged mechanical ventilation (P = .03). CONCLUSIONS: Younger age at intervention in the neonatal period was not associated with reduced morbidity or mortality in any procedural subgroup studied. In our cohort, earlier systemic-to-pulmonary shunt for obstructed pulmonary blood flow was associated with a greater likelihood of a poor outcome.

Rate of increase in serum lactate level risk-stratifies infants after surgery for congenital heart disease.

OBJECTIVE: Increased blood lactate levels reflect tissue oxygen debt and might be indicative of low cardiac output. We hypothesized that the rate of increase in serum lactate would be an ideal marker to discriminate between infants at high and low risk of a poor outcome after surgical repair of congenital heart disease using cardiopulmonary bypass. METHODS: In the present prospective, observational study in a pediatric cardiac intensive care unit, infants (aged <12 months) undergoing cardiac surgery had serial whole blood lactate levels measured with every arterial blood gas drawn for the first 24 postoperative hours. The composite poor outcome included death, the need for extracorporeal support, and dialysis. RESULTS: The lactate levels were measured in 231 infants; 19 infants (8.2%) had a poor outcome. A lactate increase rate of 0.6 mmol/L/h had very good discriminatory ability (area under the curve [AUC], 0.89) with a sensitivity of 90%, specificity of 84%, positive predictive value (PPV) of 34%, and negative predictive value (NPV) of 99%. Similar results were obtained for subgroups stratified by 1- or 2-ventricle heart disease and risk adjustment for congenital heart surgery (RACHS-1) score. In neonates (age <30 days) with single-ventricle physiology (n = 43, poor outcome = 8), a lactate increase of 0.6 mmol/L/h had near perfect discriminatory ability (AUC 0.99) with a sensitivity of 100%, specificity of 51%, PPV of 32%, and NPV of 100%. In 2-ventricle neonates (n = 43, poor outcome = 5), a lactate increase of 0.6 mmol/L/h also had near perfect discriminatory ability (AUC, 0.99), with a sensitivity of 100%, specificity of 90%, PPV of 56%, and NPV of 100%. CONCLUSIONS: The postoperative lactate increase rate allows discrimination between infants at high and low risk of morbidity and mortality after congenital heart disease surgery, and the lactate level can be followed serially for the treatment response.

Tight glycemic control versus standard care after pediatric cardiac surgery.

BACKGROUND: In some studies, tight glycemic control with insulin improved outcomes in adults undergoing cardiac surgery, but these benefits are unproven in critically ill children at risk for hyperinsulinemic hypoglycemia. We tested the hypothesis that tight glycemic control reduces morbidity after pediatric cardiac surgery. METHODS: In this two-center, prospective, randomized trial, we enrolled 980 children, 0 to 36 months of age, undergoing surgery with cardiopulmonary bypass. Patients were randomly assigned to either tight glycemic control (with the use of an insulin-dosing algorithm targeting a blood glucose level of 80 to 110 mg per deciliter [4.4 to 6.1 mmol per liter]) or standard care in the cardiac intensive care unit (ICU). Continuous glucose monitoring was used to guide the frequency of blood glucose measurement and to detect impending hypoglycemia. The primary outcome was the rate of health care-associated infections in the cardiac ICU. Secondary outcomes included mortality, length of stay, organ failure, and hypoglycemia. RESULTS: A total of 444 of the 490 children assigned to tight glycemic control (91%) received insulin versus 9 of 490 children assigned to standard care (2%). Although normoglycemia was achieved earlier with tight glycemic control than with standard care (6 hours vs. 16 hours, P<0.001) and was maintained for a greater proportion of the critical illness period (50% vs. 33%, P<0.001), tight glycemic control was not associated with a significantly decreased rate of health care-associated infections (8.6 vs. 9.9 per 1000 patient-days, P=0.67). Secondary outcomes did not differ significantly between groups, and tight glycemic control did not benefit high-risk subgroups. Only 3% of the patients assigned to tight glycemic control had severe hypoglycemia (blood glucose <40 mg per deciliter [2.2 mmol per liter]). CONCLUSIONS: Tight glycemic control can be achieved with a low hypoglycemia rate after cardiac surgery in children, but it does not significantly change the infection rate, mortality, length of stay, or measures of organ failure, as compared with standard care. (Funded by the National Heart, Lung, and Blood Institute and others; SPECS ClinicalTrials.gov number, NCT00443599.).

Junctional ectopic tachycardia after infant heart surgery: incidence and outcomes.

Junctional ectopic tachycardia (JET) is an arrhythmia observed almost exclusively after open heart surgery in children. Current literature on JET has not focused on patients at the highest risk of both developing and being negatively impacted by JET. The purpose of this study was to determine the overall incidence of JET in an infant patient cohort undergoing open cardiac surgery, to identify patient- and procedure-related factors associated with developing JET, and to assess the clinical impact of JET on patient outcomes. We performed a nested case-control study from the complete cohort of patients at our institution younger than 1 year of age who underwent open heart surgery between 2005 and 2010. JET patients were compared with an age matched control group undergoing open heart surgery without JET regarding potential risk factors and outcomes. The overall incidence of JET in infants after open cardiac surgery was 14.3 %. From multivariate analyses, complete repair of tetralogy of Fallot [adjusted odds ratio (AOR) 2.0, 95 % CI 1.12-3.57] and longer aortic cross clamp times (AOR 1.02, 95 % CI 1.01-1.03) increased the risk of developing JET. Patients with JET had longer length of intubation, intensive care unit stays, and total length of hospitalization, and were more likely to require extracorporeal membrane oxygenation support (13 vs. 4.3 %). JET is a common postoperative arrhythmia in infants after open heart operations. Both anatomic substrate and surgical procedure contribute to the overall risk of developing JET. Developing JET is associated with worse clinical outcomes.

Retrospective database research in pediatric cardiology and congenital heart surgery: an illustrative example of limitations and possible solutions.

BACKGROUND: Secondary use of data, whether from clinical information systems or registries, for carrying out clinical research in rare diseases is a common practice but is fraught with potential errors. We sought to elucidate some of the limitations of database research and describe possible solutions to overcome these limitations. METHODS: Using a disease model of a rare postsurgical outcome, we evaluated the ability of four different data sources to correctly identify patients who had that outcome both as individual databases and also when used in conjunction with each other. These results were compared with manual chart review. RESULTS: The sensitivity of the various databases to pick up a rare and specific outcome was poor (9.9%-37%), while the specificities were fairly good (91%-96.7%). By combining the databases, the sensitivity was increased to as much as 56.8% without a large decrease in the specificity (85.2%-91.6%). The electronic medical record (EMR) search engine had the highest sensitivity (96.9%) and a high specificity (89.3%) with a very high negative predictive value (99.4%). CONCLUSION: For rare and specific diseases or outcomes, a single data source search methodology can miss large numbers of patients and potentially bias study results. Combining overlapping databases can improve the ability to capture these rare diseases or outcomes. While chart review remains the most accurate way to obtain complete case capture, new tools like EMR search engines can facilitate the efficiency of this process without sacrificing search quality.

Impact of vitamin C on endothelial function and exercise capacity in patients with a Fontan circulation.

OBJECTIVE: To evaluate the impact of antioxidant therapy on functional health status in Fontan-palliated patients. Design. Prospective, randomized, double-blind, placebo-controlled trial. PATIENTS: Fifty-three generally asymptomatic Fontan patients. INTERVENTIONS: Patients were randomized to receive either high-dose ascorbic acid (vitamin C) or placebo for 4 weeks. OUTCOME MEASURES: Peripheral vascular function, as measured with endothelium-dependent digital pulse amplitude testing (EndoPAT), and exercise capacity were assessed before and after study drug treatment. Primary outcome measures included the EndoPAT index and peripheral arterial tonometry (PAT) ratio, both validated markers of vascular function. Secondary outcome measures included peak oxygen consumption and work. RESULTS: Twenty-three vitamin C- and 21 placebo-assigned subjects completed the protocol (83%). Median age and time from Fontan completion were 15 (interquartile range [IQR] 11.7-18.2) and 11.9 years (IQR 9.0-15.7), respectively. Right ventricular morphology was dominant in 30 (57%). Outcome measures were similar between groups at baseline. Among all subjects, vitamin C therapy was not associated with a statistical improvement in either primary or secondary outcome measures. In subjects with abnormal vascular function at baseline, compared with placebo, vitamin C therapy more frequently resulted in normalization of the EndoPAT index (45% vs. 17%) and PAT ratio (38% vs. 13%). CONCLUSIONS: Short-term therapy with vitamin C does not alter endothelial function or exercise capacity in an asymptomatic Fontan population overall. Vitamin C may provide benefit to a subset of Fontan patients with abnormal vascular function.