Age-dependent sex effects on outcomes after pediatric cardiac surgery

Sex differences in metabolic adaptation in infants with cyanotic congenital heart disease

BACKGROUND

Female infants with congenital heart disease (CHD) face significantly higher postoperative mortality rates after adjusting for cardiac complexity. Sex differences in metabolic adaptation to cardiac stressors may be an early contributor to cardiac dysfunction. In adult diseases, hypoxic/ischemic cardiomyocytes undergo a cardioprotective metabolic shift from oxidative phosphorylation to glycolysis which appears to be regulated in a sexually dimorphic manner. We hypothesize sex differences in cardiac metabolism are present in cyanotic CHD and detectable as early as the infant period.

METHODS

RNA sequencing was performed on blood samples (cyanotic CHD cases, n = 11; controls, n = 11) and analyzed using gene set enrichment analysis (GSEA). Global plasma metabolite profiling (UPLC-MS/MS) was performed using a larger representative cohort (cyanotic CHD, n = 27; non-cyanotic CHD, n = 11; unaffected controls, n = 12).

RESULTS

Hallmark gene sets in glycolysis, fatty acid metabolism, and oxidative phosphorylation were significantly enriched in cyanotic CHD females compared to male counterparts, which was consistent with metabolomic differences between sexes. Minimal sex differences in metabolic pathways were observed in normoxic patients (both controls and non-cyanotic CHD cases).

CONCLUSION

These observations suggest underlying differences in metabolic adaptation to chronic hypoxia between males and females with cyanotic CHD.

IMPACT

Children with cyanotic CHD exhibit sex differences in utilization of glycolysis vs. fatty acid oxidation pathways to meet the high-energy demands of the heart in the neonatal period. Transcriptomic and metabolomic results suggest that under hypoxic conditions, males and females undergo metabolic shifts that are sexually dimorphic. These sex differences were not observed in neonates in normoxic conditions (i.e., non-cyanotic CHD and unaffected controls). The involved metabolic pathways are similar to those observed in advanced heart failure, suggesting metabolic adaptations beginning in the neonatal period may contribute to sex differences in infant survival.

Promising results of a clinical feasibility study: CIRBP as a potential biomarker in pediatric cardiac surgery

Objective

Cold-inducible RNA binding Protein (CIRBP) has been shown to be a potent inflammatory mediator and could serve as a novel biomarker for inflammation. Systemic inflammatory response syndrome (SIRS) and capillary leak syndrome (CLS) are frequent complications after pediatric cardiac surgery increasing morbidity, therefore early diagnosis and therapy is crucial. As CIRBP serum levels have not been analyzed in a pediatric population, we conducted a clinical feasibility establishing a customized magnetic bead panel analyzing CIRBP in pediatric patients undergoing cardiac surgery.

Methods

A prospective hypothesis generating observational clinical study was conducted at the German Heart Center Berlin during a period of 9 months starting in May 2020 (DRKS00020885, https://drks.de/search/de/trial/DRKS00020885). Serum samples were obtained before the cardiac operation, upon arrival at the pediatric intensive care unit, 6 and 24 h after the operation in patients up to 18 years of age with congenital heart disease (CHD). Customized multiplex magnetic bead-based immunoassay panels were developed to analyze CIRBP, Interleukin-1β (IL-1β), Interleukin-6 (IL-6), Interleukin-8 (IL-8), Interleukin-10 (IL-10), Monocyte chemotactic protein 1 (MCP-1), Syndecan-1 (SDC-1), Thrombomodulin (TM), Vascular endothelial growth factor (VEGF-A), Angiopoietin-2 (Ang-2), and Fibroblast growth factor 23 (FGF-23) in 25 µl serum using the Luminex MagPix® system.

Results

19 patients representing a broad range of CHD (10 male patients, median age 2 years, 9 female patients, median age 3 years) were included in the feasibility study. CIRBP was detectable in the whole patient cohort. Relative to individual baseline values, CIRBP concentrations increased 6 h after operation and returned to baseline levels over time. IL-6, IL-8, IL-10, and MCP-1 concentrations were significantly increased after operation and except for MCP-1 concentrations stayed upregulated over time. SDC-1, TM, Ang-2, as well as FGF-23 concentrations were also significantly increased, whereas VEGF-A concentration was significantly decreased after surgery.

Discussion

Using customized magnetic bead panels, we were able to detect CIRBP in a minimal serum volume (25 µl) in all enrolled patients. To our knowledge this is the first clinical study to assess CIRBP serum concentrations in a pediatric population.

The Year in Review: Anesthesia for Congenital Heart Disease 2020

This review focuses on the literature published during the calendar year 2020 that is of interest to anesthesiologists taking care of children and adults with congenital heart disease. Five major themes are discussed, including COVID-19 in children with heart disease, race and outcome disparities in congenital heart disease, Norwood procedure and outcomes, Fontan procedure and outcomes, and neurotoxicity/neurologic outcomes. A total of 59 peer-reviewed articles are discussed.

Gender and birth weight as risk factors for anastomotic stricture after esophageal atresia repair: a systematic review and meta-analysis

Background

Anastomotic stricture (AS) is the most frequently occurring complication that occurs after esophageal atresia (EA) repair. Nevertheless, the pathogenesis remains primarily unknown and there is inadequate knowledge regarding the risk factors for AS. Therefore, a systematic review of the literature and a meta-analysis was performed to investigate whether gender and birth weight were risk factors for the development of AS following EA repair.

Methods

The main outcome measure was the occurrence of AS. Forest plots with odds ratios (OR) and 95% confidence intervals (CI) were generated for the outcomes. Quality assessment was performed using the Newcastle–Ottawa scale.

Results

Six studies with a total of 495 patients were included; 59% males, and 37 and 63% of the patients weighed < 2500 g and ≥ 2500 g, respectively. Male gender (OR, 0.96; 95% CI, 0.66–1.40; p = 0.82) and birth weight < 2500 g (OR, 0.74; 95% CI, 0.47–1.15; p = 0.18) did not increase the risk of AS. The majority of the included studies were retrospective cohort studies and the overall risk of bias was considered to be low to moderate.

Conclusion

Neither gender nor birth weight appear to have an impact on the risk of AS development following EA repair.

US Mortality Attributable to Congenital Heart Disease Across the Lifespan From 1999 Through 2017 Exposes Persistent Racial/Ethnic Disparities

BACKGROUND

Congenital heart disease (CHD) accounts for ≈40% of deaths in US children with birth defects. Previous US data from 1999 to 2006 demonstrated an overall decrease in CHD mortality. Our study aimed to assess current trends in US mortality related to CHD from infancy to adulthood over the past 19 years and determine differences by sex and race/ethnicity.

METHODS

We conducted an analysis of death certificates from 1999 to 2017 to calculate annual CHD mortality by age at death, race/ethnicity, and sex. Population estimates used as denominators in mortality rate calculations for infants were based on National Center for Health Statistics live birth data. Mortality rates in individuals ≥1 year of age used US Census Bureau bridged-race population estimates as denominators. We used joinpoint regression to characterize temporal trends in all-cause mortality, mortality resulting directly attributable to and related to CHD by age, race/ethnicity, and sex.

RESULTS

There were 47.7 million deaths with 1 in 814 deaths attributable to CHD (n=58 599). Although all-cause mortality decreased 16.4% across all ages, mortality resulting from CHD declined 39.4% overall. The mean annual decrease in CHD mortality was 2.6%, with the largest decrease for those >65 years of age. The age-adjusted mortality rate decreased from 1.37 to 0.83 per 100 000. Males had higher mortality attributable to CHD than females throughout the study, although both sexes declined at a similar rate (≈40% overall), with a 3% to 4% annual decrease between 1999 and 2009, followed by a slower annual decrease of 1.4% through 2017. Mortality resulting from CHD significantly declined among all races/ethnicities studied, although disparities in mortality persisted for non-Hispanic Blacks versus non-Hispanic Whites (mean annual decrease 2.3% versus 2.6%, respectively; age-adjusted mortality rate 1.67 to 1.05 versus 1.35 to 0.80 per 100 000, respectively).

CONCLUSIONS

Although overall US mortality attributable to CHD has decreased over the past 19 years, disparities in mortality persist for males in comparison with females and for non-Hispanic Blacks in comparison with non-Hispanic Whites. Determining factors that contribute to these disparities such as access to quality care, timely diagnosis, and maintenance of insurance will be important moving into the next decade.

Transplantation-free survival after Norwood surgery for hypoplastic left heart syndrome with aortic atresia: A Swedish national cohort study

BACKGROUND

Norwood surgery has been available in Sweden since 1993. In this national cohort study, we analysed transplantation-free survival after Norwood surgery for hypoplastic left heart syndrome with aortic atresia.

METHODS

Patients were identified from the complete national cohort of live-born with hypoplastic left heart syndrome/aortic atresia 1993-2010. Analysis of survival after surgery was performed using Cox proportional hazards models for the total cohort and for birth period and gender separately. Thirty-day mortality and inter-stage mortality were analysed. Patients were followed until September 2016.

RESULTS

The 1993-2010 cohort consisted of 208 live-born infants. Norwood surgery was performed in 121/208 (58%). The overall transplantation-free survival was 61/121 (50%). The survival was higher in the late period (10-year survival 63%) than in the early period (10-year survival 40%) (p = 0.010) and lower for female (10-year survival 34%) than for male patients (10-year survival 59%) (p = 0.002). Inter-stage mortality between stages I and II decreased from 23 to 8% (p = 0.008). For male patients, low birthweight in relation to gestational age was a factor associated with poor outcome.

CONCLUSION

The survival after Norwood surgery for hypoplastic left heart syndrome/aortic atresia improved by era of surgery, mainly explained by improved survival between stages I and II. Female gender was a significant risk factor for death or transplantation. For male patients, there was an increased risk of death when birthweight was lower than expected in relation to gestational age.

Mortality Following Pediatric Congenital Heart Surgery: An Analysis of the Causes of Death Derived From the National Death Index

Background

Prior research has focused on early outcomes after congenital heart surgery, but less is known about later risks. We aimed to determine the late causes of death among children (<21 years of age) surviving their initial congenital heart surgery.

Methods and Results

This is a retrospective cohort study from the Pediatric Cardiac Care Consortium, a US‐based registry of interventions for congenital heart defects (CHD). Excluding patients with chromosomal anomalies or inadequate identifiers, we matched those surviving their first congenital heart surgery (1982–2003) against the National Death Index through 2014. Causes of death were obtained from the National Death Index to calculate cause‐specific standardized mortality ratios (SMRs). Among 31 132 patients, 2527 deaths (8.1%) occurred over a median follow‐up period of 18 years. Causes of death varied by time after surgery and severity of CHD but, overall, 69.9% of deaths were attributed to the CHD or another cardiovascular disorder, with a SMR for CHD/cardiovascular disorder of 67.7 (95% confidence interval: 64.5–70.8). Adjusted odds ratios revealed increased risk of death from CHD/cardiovascular disorder in females [odds ratio=1.28; 95% confidence interval (1.04–1.58); P=0.018] with leading cardiovascular disorder contributing to death being cardiac arrest (16.8%), heart failure (14.8%), and arrhythmias (9.1%). Other major causes of death included coexisting congenital malformations (4.7%, SMR: 7.0), respiratory diseases (3.6%, SMR: 8.2), infections (3.4%, SMR: 8.2), and neoplasms (2.1%, SMR: 1.9).

Conclusions

Survivors of congenital heart surgery face long‐term risks of premature mortality mostly related to residual CHD pathology, heart failure, and arrhythmias, but also to other noncardiac conditions. Ongoing monitoring is warranted to identify target factors to address residual morbidities and improve long‐term outcomes.

Metabolic Response to Stress by the Immature Right Ventricle Exposed to Chronic Pressure Overload

Background

The right ventricle exposed to chronic pressure overload exhibits hypertrophy and decompensates when exposed to stress. We hypothesize that impaired ability to increase myocardial oxidative flux through pyruvate dehydrogenase leads to hypertrophied right ventricular (RV) dysfunction when exposed to hemodynamic stress, and pyruvate dehydrogenase stimulation can improve RV function.

Methods and Results

Infant male Yorkshire piglets (13.5±0.6 kg weight, n=19) were used to assess substrate fractional contribution to the citric acid cycle after sustained pulmonary artery banding (PAB). Carbon 13–labeled glucose, lactate, and leucine, oxidative substrate tracers for the citric acid cycle, were infused into the right coronary artery on 7 to 10 days after PAB. RV systolic pressure, RV free wall thickness, and individual cardiomyocyte cell size after PAB were significantly elevated compared with the sham group. Both fractional glucose and lactate oxidations in the PAB group were >2‐fold higher than in the sham group. Pigs with overdrive atrial pacing (≈80% increase in heart rate) stress after PAB showed only a 22% increase in rate‐pressure product from baseline before atrial pacing and limited carbohydrate oxidation rate in the right ventricle. Intracoronary infusion of dichloroacetate, a pyruvate dehydrogenase agonist, produced higher rate‐pressure product (59% increase) in response to increased workload by atrial pacing in association with a marked increase in lactate oxidation.

Conclusions

The immature hypertrophied right ventricle shows limited ability to increase carbohydrate oxidation in response to tachycardia stress leading to energy supply/utilization imbalance and decreased systolic function. Enhanced pyruvate dehydrogenase activation by dichloroacetate increases energy supply and preserves hypertrophied RV contractile function during hemodynamic stress.

Current trends in racial, ethnic, and healthcare disparities associated with pediatric cardiac surgery outcomes

OBJECTIVE

Despite overall improvements in congenital heart disease outcomes, racial and ethnic disparities have continued. The purpose of this study is to examine the effect of race and ethnicity, as well as other risk factors on congenital heart surgery length of stay and in-hospital mortality.

DESIGN

From the 2012 Healthcare Cost and Utilization Project Kids Inpatient Database (KID), we identified 13 130 records with Risk Adjustment in Congenital Heart Surgery complexity score-eligible procedures. Multivariate logistic and linear regression modeling with survey weights, stratification and clustering was used to examine the relationships between predictor variables and length of stay as well as in-hospital mortality.

RESULTS

No significant mortality differences were found among all race and ethnicity groups across each age group. Black neonates and black infants had a longer length of stay (neonatal estimate = 8.73 days, P = .0034; infant estimate 1.10 days, P = .0253), relative to whites. Government-sponsored insurance was associated with increased odds of neonatal mortality (odds ratio = 1.51, P = .0055), increased length of stay in neonates (estimate = 4.26 days, P = .0009) and infants (estimate = 1.52 days, P = .0181), relative to private insurance. Government-sponsored insurance was associated with increased number of chronic conditions, which were also associated with increased LOS (estimate 8.39 days, P < .001 in neonates; estimate 3.60 days, P < .001 in infants; estimate 1.87 days, P < .001 children).

CONCLUSIONS

Racial/ethnic disparities in congenital heart surgical outcomes may be changing compared with previous studies using the KID database. Increased length of stay in children with government-sponsored insurance may reflect expansion of individual states government-sponsored insurance eligibility criteria for children with complex chronic medical conditions. These findings warrant cautious optimism regarding racial and ethnic disparities in congenital heart surgery outcomes.

Risk factors of sepsis after open congenital cardiac surgery in infants: a pilot study

Background: Postsurgical sepsis is one of the main causes of the high mortality and morbidity after open congenital heart surgery in infants.  This study aimed to evaluate the role of cardiopulmonary bypass duration, thymectomy, surgical complexity, and nutritional status on postsurgical sepsis after open congenital cardiac surgery in infants.Methods: A total of 40 patients <1 year of age with congenital heart disease, Aristotle Basic Score (ABS) ≥6 were followed for clinical and laboratory data before and after surgery until the occurrence of signs or symptoms of sepsis or until a maximum of 7 days after surgery. Bivariate analyses were performed. Variables with p≤0.200 were then included for logistic regression.Results: Duration of cardiopulmonary bypass ≥90 minutes was associated with 5.538 increased risk of postsurgical sepsis in comparison to those ≤90 minutes (80% vs 25%, RR=5.538, p=0.006). No association was observed between the incidence of postsurgical sepsis with poor nutritional status (86% vs 84%, RR=1.059, p=1.000), thymectomy (and 50% vs 76%, RR=0.481, p=0.157), and Aristotle Basic Score (p=0.870).Conclusion: Cardiopulmonary bypass time influences the incidence of sepsis infants undergoing open congenital cardiac surgery. Further studies are needed to elaborate a number of risk factors associated with the incidence of sepsis in this population.

A population-based analysis of mortality in patients with Turner syndrome and hypoplastic left heart syndrome using the Texas Birth Defects Registry

BACKGROUND

Hypoplastic left heart syndrome (HLHS) is strongly associated with Turner syndrome (TS); outcome data when these conditions coexist is sparse. We aimed to investigate long-term survival and causes of death in this population.

METHODS

The Texas Birth Defects Registry was queried for all live born infants with HLHS during 1999-2007. We used Kaplan-Meier and Cox regression analyses to compare survival among patients with HLHS with TS (HLHS/TS+) to patients who had HLHS without genetic disorders or extracardiac birth defects (HLHS/TS-).

RESULTS

Of the 542 patients with HLHS, 11 had TS (2.0%), 71 had other extracardiac birth defects or genetic disorders, and 463 had neither. The median follow-up time was 4.2 y (interquartile range [IQR] 2.1-6.5). Comparing those with HLHS/TS+ to HLHS/TS-, 100% versus 35% were female (P < .001), and median birth weight was 2140 g (IQR 1809-2650) versus 3196 g (IQR 2807-3540, P < .001). Neonatal mortality was 36% in HLHS/TS+ versus 27% in HLHS/TS- (log rank = 0.431). Ten of the 11 TS+ patients died during the study period for cumulative mortality of 91% versus 50% (hazard ratio (HR) for TS+: 2.90, 95% CI 1.53-5.48). Six patients died prior to surgery, 5 underwent Stage 1 palliation (S1P), 3 died after S1P, 2 survived past S2P, and one of these died at age 19 mo. The underlying cause of death was listed as congenital heart disease on all the death certificates of HLHS/TS+ patients. In multivariable analysis controlling for low birth weight (<2500 g), TS remained associated with significantly increased cumulative mortality, although females without TS had higher mortality than males (HR for TS+ versus males: 2.42, 95% CI 1.24-4.73; HR for TS- females versus males: 1.41, 95% CI 1.08-1.83).

CONCLUSION

TS with HLHS is associated with significant mortality. The increased mortality in females without documented TS calls to question if TS is undetected in a portion of females with HLHS.

Factors Affecting Length of Postoperative Hospitalization for Pediatric Cardiac Operations in a Large North American Registry (1982-2007)

Surgical treatment of congenital heart disease represents a major cause of pediatric hospitalization and healthcare resource use. Larger centers may provide more efficient care with resulting shorter length of postoperative hospitalization (LOH). Data from 46 centers over 25 years were used to evaluate whether surgical volume was an important determinant of LOH using a competing risk regression strategy that concurrently accounted for deaths, transfers, and discharges with some time interactions. Earlier discharge was more likely for infants and older children compared to neonates [subhazard ratios at postoperative day 6 of 1.64 (99 % confidence interval (CI) 1.57, 1.72) and 2.67 (99 % CI 2.53, 2.80), respectively], but less likely for patients undergoing operations in Risk Adjustment for Congenital Heart Surgery categories 2, 3, 4, and 5/6 compared to category 1 [subhazard ratios at postoperative day 6 of 0.66 (99 % CI 0.64, 0.68), 0.34 (95 % CI 0.33, 0.35), 0.28 (99 % CI 0.27, 0.30), and 0.10 (99 % CI 0.09, 0.11), respectively]. There was no difference by sex [non-time-dependent subhazard ratio 1.019 (99 % CI 0.995, 1.040)]. For every 100-operation increase in center annual surgical volume, the non-time-dependent subhazard for discharge was 1.035 (99 % CI 1.006, 1.064) times greater, and center-specific exponentiated random effects ranged from 0.70 to 1.42 with a variance of 0.023. The conditional discharge rate increased with increasing age and later era. No sex-specific difference was found. Centers performing more operations discharged patients sooner than lower volume centers, but this difference appears to be too small to be of clinical significance. Interestingly, unmeasured institutional characteristics estimated by the center random effects were variable, suggesting that these played an important role in LOH and merit further investigation.

Modelling survival and mortality risk to 15 years of age for a national cohort of children with serious congenital heart defects diagnosed in infancy

BACKGROUND

Congenital heart defects (CHDs) are a significant cause of death in infancy. Although contemporary management ensures that 80% of affected children reach adulthood, post-infant mortality and factors associated with death during childhood are not well-characterised. Using data from a UK-wide multicentre birth cohort of children with serious CHDs, we observed survival and investigated independent predictors of mortality up to age 15 years.

METHODS

Data were extracted retrospectively from hospital records and death certificates of 3,897 children (57% boys) in a prospectively identified cohort, born 1992-1995 with CHDs requiring intervention or resulting in death before age one year. A discrete-time survival model accounted for time-varying predictors; hazards ratios were estimated for mortality. Incomplete data were addressed through multilevel multiple imputation.

FINDINGS

By age 15 years, 932 children had died; 144 died without any procedure. Survival to one year was 79.8% (95% confidence intervals [CI] 78.5, 81.1%) and to 15 years was 71.7% (63.9, 73.4%), with variation by cardiac diagnosis. Importantly, 20% of cohort deaths occurred after age one year. Models using imputed data (including all children from birth) demonstrated higher mortality risk as independently associated with cardiac diagnosis, female sex, preterm birth, having additional cardiac defects or non-cardiac malformations. In models excluding children who had no procedure, additional predictors of higher mortality were younger age at first procedure, lower weight or height, longer cardiopulmonary bypass or circulatory arrest duration, and peri-procedural complications; non-cardiac malformations were no longer significant.

INTERPRETATION

We confirm the high mortality risk associated with CHDs in the first year of life and demonstrate an important persisting risk of death throughout childhood. Late mortality may be underestimated by procedure-based audit focusing on shorter-term surgical outcomes. National monitoring systems should emphasise the importance of routinely capturing longer-term survival and exploring the mechanisms of mortality risk in children with serious CHDs.

Modelling survival and mortality risk to 15 years of age for a national cohort of children with serious congenital heart defects diagnosed in infancy

BACKGROUND

Congenital heart defects (CHDs) are a significant cause of death in infancy. Although contemporary management ensures that 80% of affected children reach adulthood, post-infant mortality and factors associated with death during childhood are not well-characterised. Using data from a UK-wide multicentre birth cohort of children with serious CHDs, we observed survival and investigated independent predictors of mortality up to age 15 years.

METHODS

Data were extracted retrospectively from hospital records and death certificates of 3,897 children (57% boys) in a prospectively identified cohort, born 1992-1995 with CHDs requiring intervention or resulting in death before age one year. A discrete-time survival model accounted for time-varying predictors; hazards ratios were estimated for mortality. Incomplete data were addressed through multilevel multiple imputation.

FINDINGS

By age 15 years, 932 children had died; 144 died without any procedure. Survival to one year was 79.8% (95% confidence intervals [CI] 78.5, 81.1%) and to 15 years was 71.7% (63.9, 73.4%), with variation by cardiac diagnosis. Importantly, 20% of cohort deaths occurred after age one year. Models using imputed data (including all children from birth) demonstrated higher mortality risk as independently associated with cardiac diagnosis, female sex, preterm birth, having additional cardiac defects or non-cardiac malformations. In models excluding children who had no procedure, additional predictors of higher mortality were younger age at first procedure, lower weight or height, longer cardiopulmonary bypass or circulatory arrest duration, and peri-procedural complications; non-cardiac malformations were no longer significant.

INTERPRETATION

We confirm the high mortality risk associated with CHDs in the first year of life and demonstrate an important persisting risk of death throughout childhood. Late mortality may be underestimated by procedure-based audit focusing on shorter-term surgical outcomes. National monitoring systems should emphasise the importance of routinely capturing longer-term survival and exploring the mechanisms of mortality risk in children with serious CHDs.