Preoperative Malnutrition Increases Risk of In-Hospital Mortality, Major Infection, and Longer Intensive Care Unit Stay After Ventricular Septal Defect Closure.

BACKGROUND: High energy requirements and poor feeding can lead to growth failure in patients with ventricular septal defect (VSD), but effects of preoperative malnutrition on surgical outcomes are poorly understood, especially in low-resource settings. METHODS AND RESULTS: We analyzed a cohort of children <5 years of age undergoing VSD closure at 60 global centers participating in the International Quality Improvement Collaborative for Congenital Heart Disease, 2015 to 2020. We calculated adjusted odds ratios (ORs) for in-hospital death and major infection and adjusted coefficients for duration of intensive care unit stay for 4 measures of malnutrition: severe wasting (weight-for-height Z score, <-3), moderate wasting (-3

Tricuspid mechanical valve replacement for severe tricuspid stenosis in a child who underwent surgical correction of complete atrioventricular septal defect, a rare long-term complications.

BACKGROUND: Complete atrioventricular septal defect is a complicated congenital heart malformations, and surgical correction is the best treatment, the severe tricuspid stenosis is a rare long-term complication after the surgery. CASE PRESENTATION: We report a case with the complication of severe tricuspid stenosis 7 years after the surgical correction of complete atrioventricular septal defect in a child. Then the patient underwent tricuspid mechanical valve replacement, Glenn, atrial septostomy, and circumconstriction of the right pulmonary artery. CONCLUSIONS: The patient recovered successfully with good short-term.

Machine learning prediction model of major adverse outcomes after pediatric congenital heart surgery: a retrospective cohort study.

BACKGROUND: Major adverse postoperative outcomes (APOs) can greatly affect mortality, hospital stay, care management and planning, and quality of life. This study aimed to evaluate the performance of five machine learning (ML) algorithms for predicting four major APOs after pediatric congenital heart surgery and their clinically meaningful model interpretations. METHODS: Between August 2014 and December 2021, 23 000 consecutive pediatric patients receiving congenital heart surgery were enrolled. Based on the split date of 1 January 2019, the authors selected 13 927 participants for the training cohort, and 9073 participants for the testing cohort. Four predefined major APOs including low cardiac output syndrome (LCOS), pneumonia, renal failure, and deep venous thrombosis (DVT) were investigated. Thirty-nine clinical and laboratory features were inputted in five ML models: light gradient boosting machine (LightGBM), logistic regression (LR), support vector machine, random forest, and CatBoost. The performance and interpretations of ML models were evaluated using the area under the receiver operating characteristic curve (AUC) and Shapley Additive Explanations (SHAP). RESULTS: In the training cohort, CatBoost algorithms outperformed others with the mean AUCs of 0.908 for LCOS and 0.957 for renal failure, while LightGBM and LR achieved the best mean AUCs of 0.886 for pneumonia and 0.942 for DVT, respectively. In the testing cohort, the best-performing ML model for each major APOs with the following mean AUCs: LCOS (LightGBM), 0.893 (95% CI: 0.884-0.895); pneumonia (LR), 0.929 (95% CI: 0.926-0.931); renal failure (LightGBM), 0.963 (95% CI: 0.947-0.979), and DVT (LightGBM), 0.970 (95% CI: 0.953-0.982). The performance of ML models using only clinical variables was slightly lower than those using combined data, with the mean AUCs of 0.873 for LCOS, 0.894 for pneumonia, 0.953 for renal failure, and 0.933 for DVT. The SHAP showed that mechanical ventilation time was the most important contributor of four major APOs. CONCLUSIONS: In pediatric congenital heart surgery, the established ML model can accurately predict the risk of four major APOs, providing reliable interpretations for high-risk contributor identification and informed clinical decisions-making.

Risk factors of gastrointestinal bleeding after cardiopulmonary bypass in children: a retrospective study.

Background: During cardiac surgery that involved cardiopulmonary bypass (CPB) procedure, gastrointestinal (GI) system was known to be vulnerable to complications such as GI bleeding. Our study aimed to determine the incidence and risk factors associated with GI bleeding in children who received CPB as part of cardiac surgery. Methods: This retrospective study enrolled patients aged <18 years who underwent cardiac surgery with CPB from 2013 to 2019 at Shanghai Children's Medical Center. The primary outcome was the incidence of postoperative GI bleeding in children, and the associated risk factors with postoperative GI bleeding episodes were evaluated. Results: A total of 21,893 children who underwent cardiac surgery with CPB from 2013 to 2019 were included in this study. For age distribution, 636 (2.9%) were neonates, 10,984 (50.2%) were infants, and 10,273 (46.9%) were children. Among the 410 (1.9%) patients with GI bleeding, 345 (84.2%) survived to hospital discharge. Incidence of GI bleeding in neonates, infants and children were 22.6% (144/636), 2.0% (217/10,984) and 0.5% (49/10,273), respectively. The neonates (22.6%) group was associated with highest risk of GI bleeding. Patients with GI bleeding showed longer length of hospital stays (25.8 ± 15.9 vs. 12.5 ± 8.9, P < 0.001) and higher mortality (15.9% vs. 1.8%, P < 0.001). Multivariate logistic regression analysis showed that age, weight, complicated surgery, operation time, use of extracorporeal membrane oxygenation (ECMO), low cardiac output syndrome (LCOS), hepatic injury, artery lactate level, and postoperative platelet counts were significantly associated with increased risk of GI bleeding in children with congenital heart disease (CHD) pediatric patients that underwent CPB procedure during cardiac surgery. Conclusion: The study results suggest that young age, low weight, long operation time, complicated surgery, use of ECMO, LCOS, hepatic injury, high arterial lactate level, and low postoperative platelet counts are independently associated with GI bleeding after CPB in children.

Poly(ether ether ketone) Conferred Polyolefin Separators with High Dimensional Thermal Stability for Lithium-Ion Batteries.

The traditional polyolefin separators used in lithium-ion batteries (LIBs) are plagued by limitations such as poor wetting of electrolytes and insufficient thermal stability, hindering the progress of LIBs. To overcome these limitations, we have developed a modified phase inversion technique to efficiently and durably coat polyolefin separators with poly(ether ether ketone) (PEEK). The resulting PEEK-coated polyolefin separators exhibit mechanical properties similar to those of unmodified polyolefin separators, with comparable tensile strength and modulus. Furthermore, the PEEK coating provides outstanding thermal stability, as the modified separators maintain their stability even at temperatures up to 200 °C, which is among the best results reported for polyolefin-based separators. In addition, the PEEK coating enhances ionic conductivity by more than 100% compared to polyolefin counterparts, leading to significant improvement in the electrochemical performance of prototype half cells. The modified phase inversion technique presented here offers a practical solution for coating polyolefin separators with functional polymers, paving the way for next-generation separator materials.

Morphologic classification of tracheobronchial arborization in children with congenital tracheobronchial stenosis and the associated cardiovascular defects.

Background: We sought to classify patients with congenital tracheal stenosis (CTS) according to tracheobronchial morphology and determine anatomic features associated with tracheobronchial anomalies (TBAs) and concurrent cardiovascular defects (CVDs). Methods: We enrolled 254 patients who underwent tracheoplasty between November 1, 2009 and December 30, 2018. The anatomic features of the tracheobronchial tree and cardiovascular system were abstracted from bronchoscopy, echocardiography, computerized tomography, and operative reports. Results: Four types of tracheobronchial morphology were identified: Type-1, which included normal tracheobronchial arborization (Type-1A, n = 29) and tracheal bronchus (Type-1B, n = 22); Type-2 (tracheal trifurcation; n = 49), and Type-3 (typical bridging bronchus; n = 47). Type-4 (bronchus with an untypical bridging pattern) was divided into Type-4A (involving bronchial diverticulum; n = 52) and Type-4B (absent bronchus; n = 55). Carinal compression and tracheomalacia were significantly more frequent in Type-4 patients than in the other patients (P < 0.01). CVDs were common in patients with CTS, especially in patients with Type-3 and Type-4 (P < 0.01). Persistent left superior vena cava was most common among patients with Type-3 (P < 0.01), and pulmonary artery sling was most frequent among those with Type-4 (P < 0.01). Outflow tract defects were most likely to occur in Type-1B. Early mortality was detected in 12.2% of all patients, and young age (P = 0.02), operation in the early era (P < 0.01), and bronchial stenosis (P = 0.03) were proven to be risk factors. Conclusions: We demonstrated a useful morphological classification for CTS. Bridging bronchus was most closely linked with vascular anomalies, while tracheal bronchus was frequently associated with outflow tract defects. These results may provide a clue to CTS pathogenesis.

H∞ filter-based dynamic joint carrier frequency offset and linear phase noise tracking for CO-OFDM systems.

In this paper, a robust, dynamic and joint carrier frequency offset (CFO) and linear phase noise (LPN) tracking algorithm is proposed by utilizing the H∞ filter for CO-OFDM systems. The dynamic tracking is implemented by Bayesian filtering which time-recursively updates the posterior state estimates based on the prior state information and calculated gain. To improve the robustness of the dynamic tracking process against the uncertainty of the noise terms, we adopt the H∞ filter, which designs a min-max optimization problem with a performance bound-defined constraint. The H∞ filter obtains the state estimates by limiting the worst-case estimation error, which guarantees its robustness to the system uncertain noise terms and external disturbances. After the joint estimation of CFO and LPN, we then propose a decision-feedback algorithm to achieve accurate signal detection. The accuracy and robustness of the proposed algorithm are verified in an 88.9 Gb/s 16-QAM CO-OFDM system, by comparing with the conventional extended Kalman filter (EKF) and Gaussian particle filter (GPF). Simulation results show that the MSEs of CFO and LPN by H∞ filter can reach the Cramér-Rao Lower Bounds (CRLBs) as well as the Bayesian CRLB (BCRLB), and possesses excellent noise and chromatic dispersion (CD) tolerance.

Multi-strategy improved salp swarm algorithm and its application in reliability optimization.

To improve the convergence speed and solution precision of the standard Salp Swarm Algorithm (SSA), a hybrid Salp Swarm Algorithm based on Dimension-by-dimension Centroid Opposition-based learning strategy, Random factor and Particle Swarm Optimization's social learning strategy (DCORSSA-PSO) is proposed. Firstly, a dimension-by-dimension centroid opposition-based learning strategy is added in the food source update stage of SSA to increase the population diversity and reduce the inter-dimensional interference. Secondly, in the followers' position update equation of SSA, constant 1 is replaced by a random number between 0 and 1 to increase the randomness of the search and the ability to jump out of local optima. Finally, the social learning strategy of PSO is also added to the followers' position update equation to accelerate the population convergence. The statistical results on ten classical benchmark functions by the Wilcoxon test and Friedman test show that compared with SSA and other well-known optimization algorithms, the proposed DCORSSA-PSO has significantly improved the precision of the solution and the convergence speed, as well as its robustness. The DCORSSA-PSO is applied to system reliability optimization design based on the T-S fault tree. The simulation results show that the failure probability of the designed system under the cost constraint is less than other algorithms, which illustrates that the application of DCORSSA-PSO can effectively improve the design level of reliability optimization.

Surgical management strategy of slide tracheoplasty for infants with congenital tracheal stenosis.

OBJECTIVE: The study objective was to evaluate the outcomes of slide tracheoplasty in infancy and identify predictors of adverse outcomes. METHODS: We retrospectively reviewed the clinical data of infants aged less than 1 year with congenital tracheal stenosis who underwent slide tracheoplasty at a single center from April 2010 to September 2020. RESULTS: Of 120 infants, 71.7% (86/120) had a pulmonary artery sling and 37.5% (45/120) had simultaneous intracardiac repairs. Additionally, 52.5% (63/120) of the patients had anomalous tracheobronchial arborization, and 17.5% (21/120) had diffuse tracheal stenosis. Six airway reoperations (5%) and 6 deaths (5%) occurred, and the mortality decreased annually. Multivariate analysis revealed that a low body weight, cardiovascular anomalies, and normal tracheobronchial arborization predicted a longer intubation duration. Univariate analysis revealed that a low body weight, preoperative invasive ventilation, a long cardiopulmonary bypass time, and granulation tissue were associated with death. After surgery, 26 patients had dysphagia, 24 of whom resumed oral feeding during follow-up. Ninety-two patients underwent chest computed tomography reexamination, and the trachea diameter had increased significantly from 2.32 ± 0.72 mm to 5.46 ± 1.24 mm. Nineteen and 29 patients underwent spirometry before and after surgery, respectively, and showed improvements in ventilation function, with the ratio of time to peak tidal expiratory flow to total expiratory time and ratio of volume to peak tidal expiratory flow to total expiratory volume values significantly improved from 19.80% (interquartile range, 16.90-23.80) and 23.10% (interquartile range, 21.10-25.90) to 26.80% (interquartile range, 21.20-34.40) and 30.20% (interquartile range, 25.00-34.50), respectively (P < .05). CONCLUSIONS: A tailored individual management strategy of slide tracheoplasty in infancy facilitates favorable clinical outcomes. Close postoperative follow-up and long-term functional evaluations including clinical symptoms and pulmonary function are still needed.

Surgical management of long-segment congenital tracheal stenosis with tracheobronchial malacia.

OBJECTIVES: Slide tracheoplasty has become the mainstream treatment for long-segment congenital tracheal stenosis (LSCTS). However, technical improvements are still needed to improve the clinical outcomes of patients exhibiting LSCTS with tracheobronchial malacia. METHODS: LSCTS patients who underwent tracheoplasty from January 2010 to December 2020 were reviewed. According to the time of surgical technique modifications for reconstructing a supportive carina, the patients were divided into 2 groups: group A (2010-2018) and group B (2019-2020). We identified a well-balanced cohort matched by propensity score to evaluate the differences in surgical outcomes between the 2 groups. RESULTS: There were no significant differences between group A and group B in any of the 8 characteristics before and after propensity score matching. In the propensity score-matched cohort, the number of patients who accepted anterior carina tracheopexy (75/77 vs 4/77, P < 0.001) and in situ pericardium insertion (75/77 vs 14/77, P < 0.001) in group B was significantly greater than that in group A. The mechanical ventilation time [48.3 (interquartile range: 29.6, 116.3) h vs 73.3 (interquartile range: 47.9, 111.6) h, P = 0.009] and cumulative mortality (P = 0.023) were significantly lower in Group B than Group A. CONCLUSIONS: Reconstructing a supportive, stable carina of the neotrachea and tracheobronchopexy are helpful to improve the outcomes of slide tracheoplasty.

Retrospective analysis of the effect of current clinical medications and clinicopathological factors on viral shedding in COVID-19 patients.

The aim of the present study was to identify the risk factors associated with prolonged shedding in patients with coronavirus disease 2019 (COVID-19), and to evaluate the effects of current clinical and clinicopathological factors on viral shedding in patients. A total of 186 COVID-19 inpatients were enrolled in this multicentre retrospective analysis. Detailed clinical data of each patient were collected, and the factors that affected the duration of viral shedding were retrospectively analysed. The median duration of viral shedding in the 186 COVID-19 patients was 13 days. The median duration of viral shedding was 12 days in non-severe patients, and 17 days in severe patients, and there was a significant difference between the two groups (P<0.001). Multi-factor regression analysis suggested that the onset-hospitalization interval [odds ratio (OR), 1.27; 95% confidence interval (CI), 1.15-1.41; P<0.001] and comorbidity with a chronic disease (OR, 2.43; 95% CI, 1.14-5.17; P=0.021) were independent risk factors for prolonged viral shedding, whereas lopinavir/ritonavir (LPV/r) was an independent protective factor (OR, 0.28; 95% CI, 0.11-0.75; P=0.011). Spearman's rank correlation analysis showed that the onset-drug interval was positively correlated with the duration of viral shedding (r=0.446; P<0.0001). Umifenovir, and low and short courses of glucocorticoids were not associated with prolonged viral shedding. The prolonged viral shedding was the initial causative factor of persistent aggravation of the patient's conditions. The interval between presentation of symptoms and hospitalization as well as complications with a comorbid chronic disease were independent risk factors for prolonged viral shedding. LPV/r shortened the duration of viral shedding, and the smaller the interval between presentation and LPV/r onset was, the faster viral shedding occurred.

Epidemiological and Clinical Characteristics of 26 Asymptomatic Severe Acute Respiratory Syndrome Coronavirus 2 Carriers.

BACKGROUND: We retrospectively analyzed 26 persistently asymptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) carriers. METHODS: Epidemiological and clinical characteristics from the 26 asymptomatic patients with positive results for SARS-CoV-2 ribonucleic acid testing were obtained. RESULTS: Twenty-two patients (84.6%) correlated with clustering occurrence. The median period from contact to diagnosis and the last positive nucleic acid test was 19 (8-24 days) and 21.5 days (10-36 days), respectively. The median period from diagnosis to negative nucleic acid test was significantly different between patients with normal or atypical chest computed tomography (CT) findings (n = 16, 61.5%; 7.5 days [2-20 days]) and patients with typical ground-glass or patchy opacities on CT (n = 10, 38.5%; 12.5 days [8-22 days]; P < .01). Seven patients (70.0%) with initial positive nucleic acid test results had a negative result simultaneously with improved CT findings. Obvious improvement in CT findings was observed in 3 patients (30.0%) despite positive nucleic acid test results. CONCLUSIONS: In asymptomatic patients, changes in biochemical and inflammatory variables are small and changes on chest CT can occur. It is worth noting that the long existence of SARS-CoV-2 in some asymptomatic patients and false-negative results need to be considered in SARS-CoV-2 nucleic acid test.

Morphologic Analysis of Congenital Heart Disease With Anomalous Tracheobronchial Arborization.

BACKGROUND: This study investigated the morphologic characteristics of congenital heart disease (CHD) combined with anomalous tracheobronchial arborization (ATBA) to provide new considerations for surgically treating congenital tracheal stenosis. METHODS: A retrospective review of surgical experience with ATBA was conducted of 147 patients. The proportion of patients with ATBA combined with tracheal stenosis was determined. Four ATBA types were identified: type A, tracheal bronchus (n = 58); type B, bronchial trifurcation (n = 46); type C, bridging bronchus (n = 38); and type D, tracheal bronchus combined with bronchial trifurcation (n = 5). The rate of tracheoplasty for each type was determined. We measured the carina/pseudocarina angle and assessed the distribution of CHD, especially pulmonary artery sling. RESULTS: The tracheal diameter of 14 patients (24.1%) with type A and 5 patients (10.9%) with type B was normal. There were 128 patients with tracheal stenosis and complete tracheal rings; of them, 113 patients received tracheoplasty. The tracheoplasty rate was higher for type C than type A (100% vs 62.1%, P < .001). The carina/pseudocarina angle was significantly reduced postoperatively (P < .001). The repair in 78 patients (60.9%) was combined with a pulmonary artery sling. A pulmonary azygos lobe was found in 10 patients (6.8%) and was resected. CONCLUSIONS: ATBA is common in patients with congenital tracheal stenosis and may be associated with abnormal embryonic development. The new classification of ATBA has clinical significance in treating patients with congenital tracheal stenosis. The poor tracheal development cannot be explained merely with vascular compression. Tracheoplasty is currently the optimal option for every type.

Risk factors for low cardiac output syndrome in children with congenital heart disease undergoing cardiac surgery: a retrospective cohort study.

BACKGROUND: Low cardiac output syndrome (LCOS) is an important complication of cardiac surgery. It is associated with increased morbidity and mortality. The incidence of LCOS after surgery is high in patients with congenital heart disease (CHD). Therefore, determining the risk factors of LCOS has clinical significance for the management of CHD. This study aimed to analyze the risk factors of LCOS. METHODS: We conducted a retrospective analysis of children with CHD who underwent cardiac surgery at Shanghai Children's Medical Center between January 1, 2014, and December 31, 2017. Demographic characteristics and baseline data were extracted from the health data resource center of the hospital, which integrates clinical routine data including medical records, diagnoses, orders, surgeries, laboratory tests, imaging, nursing, and other subsystems. Logistic regressions were performed to analyze the risk factors of LCOS. RESULTS: Overall, 8660 infants with CHD were included, and 864 (9.98%) had LCOS after surgery. The multivariate regression analysis identified that age (OR 0.992, 95% CI: 0.988-0.997, p = 0.001), tricuspid regurgitation (1.192, 1.072-1.326, p = 0.001), Risk Adjustment in Congenital Heart Surgery-1 risk grade (1.166, 1.011-1.345, p = 0.035), aortic shunt (left-to-right: 1.37, 1.005-1.867, p = 0.046; bi-directional: 1.716, 1.138-2.587, p = 0.01), atrial shunt (left-to-right: 1.407, 1.097-1.805, p = 0.007; right-to-left: 3.168, 1.944-5.163, p < 0.001; bi-directional: 1.87, 1.389-2.519, p < 0.001), ventricular level shunt (left-to-right: 0.676, 0.486-0.94, p = 0.02; bi-directional: 2.09, 1.611-2.712, p < 0.001), residual shunt (3.489, 1.502-8.105, p = 0.004), left ventricular outflow tract obstruction (3.934, 1.673-9.254, p = 0.002), right ventricular outflow tract obstruction (3.638, 1.225-10.798, p = 0.02), circulating temperature (mild hypothermia: 1.526, 95% CI: 1.205-1.934, p < 0.001; middle and low temperature: 1.738, 1.236-2.443, p = 0.001), duration of cardiopulmonary bypass (1.009, 1.006-1.012, p < 0.001), myocardial preservation using histidine-tryptophan-ketoglutarate (1.677, 1.298-2.167, p < 0.001), and mitral insufficiency (1.714, 1.239-2.37, p < 0.001) were independent risk predictors of LCOS. CONCLUSIONS: The incidence of postoperative LCOS in CHD children remains high. Circulation temperature, myocardial preservation using histidine-tryptophan-ketoglutarate, and usage of residual shunt after surgery were independent risk predictors for LCOS.

Tunable multiple-passband microwave photonic filter based on external optical injected Fabry-Pérot laser.

This paper proposes a tunable multiple-passband microwave photonic filter (MPF) that is incorporated with an injection-locked Fabry-Pérot (FP) laser. In the proposed MPF, multiple passbands can be easily generated based on the frequency-selection effects of the laser structure in the case of multiple light waves injection. The novelty here is that the obtained multiple-passband MPF can achieve either a dual-passband or a single-passband by using merely one experimental scheme. Moreover, since the laser injection ratio of the proposed scheme is high, the central frequency of each passband has a large tunable range. More tunable passbands can be generated by employing more external wavelengths. By fine-detuning the injection parameters, the frequency tuning range of 17 GHz and the out-of-band rejection ratio of 24.1 dB are achieved for the dual-passband MPF, and the out-of-band rejection ratio of 22 dB and the 3-dB bandwidth of 360 MHz are achieved for the single-passband MPF. In addition, the attained peak power and bandwidth of the proposed MPF are investigated with respect to the injection parameters, including detuning frequency, injection ratio and bias current of FP laser. The stability and dynamic range of the MPF are also evaluated through experiments.

Dual-template imprinted polymers for class-selective solid-phase extraction of seventeen triazine herbicides and metabolites in agro-products.

A novel dual-template molecularly imprinted polymer (DMIP) was prepared with atrazine and prometryn as the template and applied as a class-specific adsorbent for simultaneously selective solid-phase extraction of seventeen triazine herbicides and metabolites from complex matrices. For comparison, a non-imprinted polymer (NIP) and two single-template imprinted polymers (SMIPs) were also synthesized using the same procedure of DMIP, but in the absence of the template (NIP) or with one template (SMIP). Various parameters affecting the extraction performance of DMIP-SPE were investigated in detail. Under the optimum conditions, the enrichment efficiency, class-selectivity and reusability of DMIP-SPE were evaluated. Only DMIP-SPE possessed high affinity and good selective recognition ability for all the seventeen targets including chloro-, thiomethyl- and methoxy- triazines. Further, a DMIP-SPE-LC-MS/MS method was developed for simultaneously determining trace triazine herbicides and metabolites in maize, wheat and cottonseed samples. The method showed good linearity (r>0.9941) in the range of 10-200 µg kg-1, high sensitivity with low limits of detection of 0.5-8.8 µg kg-1, and satisfactory recoveries of 61.3-105.9% with relative standard deviations of 2.1-10.7%. These results highlighted the good application prospect of the multi/dual-template imprinting strategy in the high-throughput analysis of various concerned contaminants in agro-products.

Tetralogy of Fallot Repair in Developing Countries: International Quality Improvement Collaborative.

BACKGROUND: Isolated reports from low- and middle-income countries (LMICs) for surgical results in tetralogy of Fallot (TOF) are available. The International Quality Improvement Collaborative for Congenital Heart Disease (IQIC) seeks to improve surgical results promoting reductions in infection and mortality in LMICs. METHODS: All cases of TOF in the IQIC database performed between 2010 and 2014 at 32 centers in 20 LMICs were included. Excluded from the analysis were TOF with any associated lesions. A logistic regression analysis was performed to identify risk factors for in-hospital mortality after surgery for TOF. RESULTS: A total of 2,164 patients were identified. There were 1,839 initial primary repairs, 200 with initial systemic-to-pulmonary artery shunt, and 125 underwent secondary repair after initial palliation. Overall mortality was 3.6% (78 of 2,164), initial primary repair was 3.3% (60 of 1,839), initial systemic-to-pulmonary artery shunt was 8.0% (16 of 200), and secondary repair was 1.6% (2 of 125; p = 0.003). Major infections occurred in 5.9% (128 of 2,164) of the entire cohort. Risk factors for death after the initial primary repair were oxygen saturation less than 90% and weight/body mass index for age below the fifth percentile (p < 0.001). The initial primary repair occurred after age 1 year in 54% (991 of 1,839). Older age at initial primary repair was not a risk factor for death (p = 0.21). CONCLUSIONS: TOF patients are often operated on after age 1 year in LMICs. Unlike in developed countries, older age is not a risk factor for death. Nutritional and hypoxemic status were associated with higher mortality and infection. This information fills a critical knowledge gap for surgery in LMIC.