The Estimated Fick Method Systematically Over-Estimates Cardiac Index Compared to Thermodilution in Children.

Cardiac index (CI) may be derived from the Fick method, using measured or estimated oxygen consumption (VO2), or from thermodilution. In children, LaFarge VO2 estimates correlate poorly with measured VO2 values. In a large adult cohort, there was only modest correlation between estimated Fick CI (eFick CI) and thermodilution CI (TDCI). We evaluated the extent of agreement between eFick CI using LaFarge estimates of VO2 and TDCI in a pediatric cohort. A retrospective, single-center chart review of patients 3-18 years of age who underwent cardiac catheterization with documented eFick CI and TDCI from 2004 to 2020 included 201 catheterizations from 161 unique patients. The mean patient age at catheterization was 12.2y (SD 4.4y). The most frequent diagnosis was cardiomyopathy, followed by congenital heart disease and pulmonary hypertension. TDCI and eFick CI differed by > 20% in 49% of catheterizations. eFick CI systematically exceeded TDCI by a mean percentage difference of 24% (SD 31%). Higher mean CI ((eFick CI + TDCI)/2) and older age were predictive of greater percent difference between eFick CI and TDCI. For each increase in mean CI by 1.0 L/min/m2, the expected percent difference in CI increased by 9.9% (p < 0.001). In pediatric patients undergoing cardiac catheterization, eFick CI with LaFarge VO2 systematically exceeds TDCI. The difference between methods is frequently > 20%, which may have clinically significant implications. Discrepancies between eFick CI and TDCI increase at higher mean CI.

Prognostic Value of RV Function Analysis During the Interstage Period in Patients with Hypoplastic Left Heart Syndrome.

Cardiac dysfunction is associated with mortality in children with hypoplastic left heart syndrome (HLHS). We evaluated the ability of qualitative and quantitative RV functional parameters to predict outcomes in HLHS patients. In this retrospective, single-center study, echocardiograms from 3 timepoints (pre-stage 1 palliation, 4-8 weeks post-stage 1 palliation, and pre-Glenn) were analyzed in infants with HLHS. Patients were stratified into two groups based on outcome of transplant-free survival post-Glenn (survivors) versus mortality or transplantation prior to Fontan (non-survivors). Images were retrospectively reviewed to obtain RV global longitudinal strain (RVGLS), RV-free wall strain (RVFWS), fractional area change (FAC), tricuspid annular systolic plane excursion (TAPSE), tissue motion annular displacement of the tricuspid valve (TMAD-TV) and qualitative systolic function assessment during the predetermined timepoints. An equal variance t-test and chi-square were used to determine significant differences and ROC curve analysis was performed to derive optimal cutoff values to predict mortality/transplant. A total of 47 patients met inclusion criteria, of which, 21 patients met composite endpoint. There were no significant differences in any RV functional parameter during the pre- or post-stage 1 palliation timepoints. The absolute values of RVFWS, RVGLS, and TMAD-TV were significantly greater in survivors than non-survivors during the pre-Glenn timepoint. A pre-Glenn RVGLS > -15.6 (AUC 0.79), RVFWS > -18.6 (AUC 0.75), and TMAD-TV < 12.6% (AUC 0.82) were sensitive and specific for predicting death or need for transplantation prior to Fontan completion. RVGLS, RVFWS, and TMAD-TV may help identify higher-risk HLHS patients during the interstage period.

Late-gadolinium enhancement is common in older pediatric heart transplant recipients and is associated with lower ejection fraction.

BACKGROUND: Chronic graft failure and cumulative rejection history in pediatric heart transplant recipients (PHTR) are associated with myocardial fibrosis on endomyocardial biopsy (EMB). Cardiovascular magnetic resonance imaging (CMR) is a validated, non-invasive method to detect myocardial fibrosis via the presence of late gadolinium enhancement (LGE). In adult heart transplant recipients, LGE is associated with increased risk of future adverse clinical events including hospitalization and death. We describe the prevalence, pattern, and extent of LGE on CMR in a cohort of PHTR and its associations with recipient and graft characteristics. METHODS: This was a retrospective study of consecutive PHTR who underwent CMR over a 6-year period at a single center. Two independent reviewers assessed the presence and distribution of left ventricular (LV) LGE using the American Heart Association (AHA) 17-segment model. LGE quantification was performed on studies with visible fibrosis (LGE+). Patient demographics, clinical history, and CMR-derived volumetry and ejection fractions were obtained. RESULTS: Eighty-one CMR studies were performed on 59 unique PHTR. Mean age at CMR was 14.8 ± 6.2 years; mean time since transplant was 7.3 ± 5.0 years. The CMR indication was routine surveillance (without a clinical concern based on laboratory parameters, echocardiography, or cardiac catheterization) in 63% (51/81) of studies. LGE was present in 36% (29/81) of PHTR. In these LGE + studies, patterns included inferoseptal in 76% of LGE + studies (22/29), lateral wall in 41% (12/29), and diffuse, involving > 4 AHA segments, in 21% (6/29). The mean LV LGE burden as a percentage of myocardial mass was 18.0 ± 9.0%. When reviewing only the initial CMR per PHTR (n = 59), LGE + patients were older (16.7 ± 2.9 vs. 12.8 ± 4.6 years, p = 0.001), with greater time since transplant (8.3 ± 5.4 vs. 5.7 ± 3.9 years, p = 0.041). These patients demonstrated higher LV end-systolic volume index (LVESVI) (34.7 ± 11.7 vs. 28.7 ± 6.1 ml/m2, p = 0.011) and decreased LV ejection fraction (LVEF) (56.2 ± 8.1 vs. 60.6 ± 5.3%, p = 0.015). There were no significant differences in history of moderate/severe rejection (p = 0.196) or cardiac allograft vasculopathy (CAV) (p = 0.709). CONCLUSIONS: LV LGE was present in approximately one third of PHTR, more commonly in older patients with longer time since transplantation. Grafts with LGE have lower LVEF. CMR-derived LGE may aid in surveillance of chronic graft failure in PHTR.

Age Matters: A Comparative Study of RF Heating of Epicardial and Endocardial Electronic Devices in Pediatric and Adult Phantoms during Cardiothoracic MRI.

This study focused on the potential risks of radiofrequency-induced heating of cardiac implantable electronic devices (CIEDs) in children and adults with epicardial and endocardial leads of varying lengths during cardiothoracic MRI scans. Infants and young children are the primary recipients of epicardial CIEDs, though the devices have not been approved as MR conditional by the FDA due to limited data, leading to pediatric hospitals either refusing the MRI service to most pediatric CIED patients or adopting a scan-all strategy based on results from adult studies. The study argues that risk-benefit decisions should be made on an individual basis. We used 120 clinically relevant epicardial and endocardial device configurations in adult and pediatric anthropomorphic phantoms to determine the temperature rise during RF exposure at 1.5 T. The results showed that there was significantly higher RF heating of epicardial leads than endocardial leads in the pediatric phantom, but not in the adult phantom. Additionally, body size and lead length significantly affected RF heating, with RF heating up to 12 °C observed in models based on younger children with short epicardial leads. The study provides evidence-based knowledge on RF-induced heating of CIEDs and highlights the importance of making individual risk-benefit decisions when assessing the potential risks of MRI scans in pediatric CIED patients.

Association Between Prenatal Diagnosis and Age at Surgery for Noncritical and Critical Congenital Heart Defects.

BACKGROUND: The relationship between the prenatal diagnosis of congenital heart defects (CHDs) and age at CHD surgery is poorly understood, despite the known relationships between age at surgery and long-term outcomes. The objective of this study was to determine the associations between prenatal diagnosis of CHD and age at surgery, and whether these associations differ for critical and noncritical CHDs. METHODS: This is a cohort analysis of patients aged 0 to 9 years who received their initial cardiac surgery at Ann & Robert H. Lurie Children's Hospital of Chicago between 2015 and 2021 with prenatal diagnosis as the exposure variable. All data were obtained from the locally maintained Society of Thoracic Surgeons Congenital Heart Surgery Database at Lurie Children's Hospital. We used multivariable fixed effects regression models to estimate the strength of the association of prenatal diagnosis with age at surgery among patients with critical (surgery ≤60 days) and noncritical (surgery >60 days) CHDs. RESULTS: Of 1131 individuals who met inclusion criteria, 532 (47%) had a prenatal diagnosis, 428 (38%) had critical CHDs, 533 (47%) were female, and the median age at surgery was 119 days (interquartile range, 11-309 days). After controlling for demographics, comorbidities, and surgical complexity, the mean age at surgery was significantly younger in those with prenatally versus postnatally diagnosed critical CHD (7.1 days sooner, P<0.001) and noncritical CHDs (atrial septal defects [12.4 months sooner, P=0.037], ventricular septal defects [6.0 months sooner, P<0.003], and noncritical coarctation of the aorta [1.8 months sooner, P=0.010]). CONCLUSIONS: Younger age at CHD surgery, which is associated with postsurgical neurodevelopmental and physical outcomes, is significantly associated with prenatal CHD diagnosis. This relationship was identified for both critical and noncritical CHDs.

Cardiovascular Manifestations of Turner Syndrome: Phenotypic Differences Between Karyotype Subtypes.

Turner syndrome (TS) is a genetic disorder presenting in phenotypic females with total or partial monosomy of the X chromosome. Cardiovascular abnormalities are common, including congenital heart defects (CHD) and aortic dilation. Although mosaic TS is suspected to have less severe phenotype as compared to non-mosaic TS, differences in cardiovascular manifestations between karyotypes are not well studied. This is a single-center retrospective cohort study including patients with TS seen from 2000 to 2022. Demographic data, chromosomal analysis, and imaging were reviewed. Karyotypes were categorized as monosomy X (45X), 45X mosaicism, isochromosome Xq, partial X deletions, ring X (r(X)), TS with Y material, and others. Prevalence of CHD and aortic dilation were compared between monosomy X and other subtypes using Pearson's chi-square test and Welch two-sample t-test. We included 182 TS patients with median age 18 (range 4-33) years. CHD was more common in monosomy X as compared with others (61.4% vs. 26.8%, p < 0.001), including bicuspid aortic valve (44.3% vs. 16.1%, p < 0.001), partial anomalous pulmonary venous return (12.9% vs. 2.7%, p = 0.023), persistent left superior vena cava (12.9% vs. 1.8%, p = 0.008), and coarctation of the aorta (20.0% vs. 4.5%, p = 0.003). Cardiac surgery (24.3% vs. 8.9%, p = 0.017) was more prevalent in the monosomy X group. There was no statistically significant difference for presence of aortic dilation (7.1% vs 1.8%, p = 0.187). Although CHD and need for cardiac surgery are more common in TS with monosomy X as compared to others, all TS subtypes may have similar risk of developing aortic dilation. All TS patients should have similar cardiovascular surveillance testing to monitor for aortic dilation.

Prevalence of Abnormal Hemoglobin A1c Values in Single Ventricle Patients Following Fontan Palliation.

Fontan palliation has improved survival in single ventricle patients. However, Fontan patients are subject to long-term morbidity. A few previous studies suggest Fontan patients have an increased risk of abnormal glucose metabolism without a clear mechanism. We aim to evaluate the prevalence and severity of abnormal hemoglobin A1c (HbA1c) values in Fontan patients and identify associated factors. Single-center retrospective cross-sectional cohort study including Fontan patients and documented HbA1c testing. Univariate demographic, anthropometric, and laboratory variable comparisons were completed and a stepwise selection multivariate regression model was attempted. The study included 414 Fontan patients, median age of 19 years (range 3-59 years). Of these, 190 patients (60.5% male) had at least one HbA1c. Abnormal HbA1c (> 5.6%) was found in 36% (n = 70) and diabetic-range HbA1c (≥ 6.5%) in 4.7% (n = 9). Factors associated with abnormal HbA1c included non-white race (63% vs 45%, p = 0.018), female sex (49% vs 34%, p = 0.050), elevated adult BMI [29.6 (± 8.4) vs 24.8 (± 4.8), p = < 0.0001], elevated blood glucose [108.7 (± 47.3) vs 91.1 (± 17.9), p = < 0.0001], and elevated triglycerides [101.5 (± 52.9) vs 84.1 (± 50.9), p = 0.029]. There were no significant differences found between the two HbA1c groups regarding cardiac diagnoses or surgical factors including type of stage 1 procedure, type of stage 3 procedure, or fenestration of Fontan. Patient age at time of initial Fontan procedure and time since initial Fontan showed no association with abnormal glucose metabolism. Obesity (BMI z-score ≥ 1.6 in children and BMI ≥ 30 in adults) was correlated with abnormal HbA1c (p = 0.008, 95%CI 0.069-0.45). There is a high prevalence of elevated HbA1c values in Fontan patients with modifiable associated factors, such as obesity and hypertriglyceridemia. Further investigation is needed to identify additional associated factors for abnormal glucose metabolism and determine its clinical significance. Lastly, we propose a new management protocol to screen for abnormal glucose metabolism.