Fetal cardiac and neonatal cerebral hemodynamics and oxygen metabolism in transposition of the great arteries

Electroencephalography and optical neuromonitoring predict short-term outcomes in neonates undergoing therapeutic hypothermia for hypoxic-ischemic encephalopathy

Electroencephalography (EEG) and optical neuromonitoring were used to predict short-term outcomes in neonates undergoing therapeutic hypothermia (TH) for hypoxic-ischemic encephalopathy (HIE). Fifty-two neonates undergoing TH for HIE were prospectively recruited. Continuous EEG monitoring was initiated within 24 h of life and a quantitative discontinuity index was calculated. Combined frequency-domain near infrared spectroscopy (FDNIRS) and diffuse correlation spectroscopy (DCS) were initiated within 48 h of life and used to measure cerebral hemoglobin oxygen saturation (SO2) and a cerebral blood flow index. Using these parameters and hemoglobin concentration measurements, cerebral oxygen extraction fraction (OEF), indices of cerebral oxygen delivery and metabolism (CMRO2i) as well as cerebral oxygen reserve (CRO2) were derived. Short-term outcome was classified based on brain injury pattern on magnetic resonance imaging and/or death; as normal-mild, moderate or severe outcome. Results showed that EEG discontinuity index, SO2 and CRO2 were higher and OEF lower in neonates with severe compared to normal-mild and moderate outcomes during TH. EEG discontinuity index was the most accurate and earliest parameter to identify moderate vs. severe outcomes while CMRO2i identified normal-mild vs. moderate outcomes as early as day 2 of TH. Combining EEG and FDNIRS-DCS parameters improved area-under-the-curve, sensitivity and specificity for most of the predictive models.

Neuromonitoring practices for neonates with congenital heart disease: a scoping review

Neonates with congenital heart disease (CHD) are at risk for adverse neurodevelopmental outcomes. This scoping review summarizes neuromonitoring methods in neonates with CHD. We identified 84 studies investigating the use of near-infrared spectroscopy (NIRS) (n = 37), electroencephalography (EEG) (n = 20), amplitude-integrated electroencephalography (aEEG) (n = 10), transcranial Doppler sonography (TCD) (n = 6), and multimodal monitoring (n = 11). NIRS was used to evaluate cerebral oxygenation, identify risk thresholds and adverse events in the intensive care unit (ICU), and outcomes. EEG was utilized to screen for seizures and to predict adverse outcomes. Studies of aEEG have focused on characterizing background patterns, detecting seizures, and outcomes. Studies of TCD have focused on correlation with short-term clinical outcomes. Multimodal monitoring studies characterized cerebral physiologic dynamics. Most of the studies were performed in single centers, had a limited number of neonates (range 3-183), demonstrated variability in neuromonitoring practices, and lacked standardized approaches to neurodevelopmental testing. We identified areas of improvement for future research: (1) large multicenter studies to evaluate developmental correlates of neuromonitoring practices; (2) guidelines to standardize neurodevelopmental testing methodologies; (3) research to address geographic variation in resource utilization; (4) integration and synchronization of multimodal monitoring; and (5) research to establish a standardized framework for neuromonitoring techniques across diverse settings. IMPACT: This scoping review summarizes the literature regarding neuromonitoring practices in neonates with congenital heart disease (CHD). The identification of low cerebral oxygenation thresholds with NIRS may be used to identify neonates at risk for adverse events in the ICU or adverse neurodevelopmental outcomes. Postoperative neuromonitoring with continuous EEG screening for subclinical seizures and status epilepticus, allow for early and appropriate therapy. Future studies should focus on enrolling larger multicenter cohorts of neonates with CHD with a standardized framework of neuromonitoring practices in this population. Postoperative neurodevelopmental testing should utilize standard assessments and testing intervals.

Lung volumes are increased in fetuses with transposition of the great arteries on intrauterine MRI

Fetal brain size is decreased in some children with complex CHDs, and the distribution of blood and accompanying oxygen and nutrients is regionally skewed from early fetal life dependent on the CHD. In transposition of the great arteries, deoxygenated blood preferentially runs to the brain, whereas the more oxygenated blood is directed towards the lungs and the abdomen. Knowledge of whether this impacts intrauterine organ development is limited. We investigated lung, liver, and total intracranial volume in fetuses with transposition of the great arteries using MRI.Eight fetuses with dextro-transposition and without concomitant disease or chromosomal abnormalities and 42 fetuses without CHD or other known diseases were scanned once or twice at gestational age 30 through 39 weeks. The MRI scans were conducted on a 1.5T system, using a 2D balanced steady-state free precession sequence. Slices acquired covered the entire fetus, slice thickness was 10 mm, pixel size 1.5 × 1.5 mm, and scan duration was 30 sec.The mean lung z score was significantly larger in fetuses with transposition compared with those without a CHD; mean difference is 1.24, 95% CI:(0.59;1.89), p < 0.001. The lung size, corrected for estimated fetal weight, was larger than in the fetuses without transposition; mean difference is 8.1 cm3/kg, 95% CI:(2.5;13.7 cm3/kg), p = 0.004.In summary, fetuses with dextro-transposition of the great arteries had both absolute and relatively larger lung volumes than those without CHD. No differences were seen in liver and total intracranial volume. Despite the small number of cases, the results are interesting and warrant further investigation.

Cardiovascular Ultrasound Predictors for Brain Alterations in Fetuses With Heart Disease: An Exploratory Review of the Literature

OBJECTIVE

To identify cardiovascular ultrasound predictors for brain anomalies in fetuses with heart disease.

METHODS

A literature search was performed in the following databases: MEDLINE through OVID, EMBASE, Cochrane Registry Center for Controlled Trials (CENTRAL), and LILACS, from their inception until May 2023. Clinical studies, cross-sectional studies, case-control studies, cohorts, and systematic reviews were included. Data extraction was performed, and the risk of bias was assessed using the QUADAS-2 tool.

RESULTS

Among 2705 studies evaluated, after filtering information, 10 articles were selected that met the inclusion criteria. These studies noted the following outcomes: a decrease in fetal head circumference, changes in brain maturation measured in days, decreased depth of brain fissures, and a decrease in total brain volume. The studies show a statistically significant correlation with the presence of the following cardiovascular predictors: low or mixed oxygen content in the ascending aorta (p < 0.001), retrograde flow in the aortic arch (p < 0.001), lower z values of the MCA-PI (p < 0.05), higher UA-PI z values (p < 0.01), and lower CPR (p < 0.05). In addition, lower values of left ventricular flow (p < 0.01), ductus arteriosus (p < 0.0001), and combined cardiac output index (p < 0.01) were reported.

CONCLUSIONS

This review describes the most relevant evidence correlating the effects of hemodynamic changes that lead to states of chronic hypoxia related to the aforementioned changes in the central nervous system.