Cerebral oxygen metabolism in neonates with congenital heart disease quantified by MRI and optics.

Neonatal congenital heart disease (CHD) is associated with altered cerebral hemodynamics and increased risk of brain injury. Two novel noninvasive techniques, magnetic resonance imaging (MRI) and diffuse optical and correlation spectroscopies (diffuse optical spectroscopy (DOS), diffuse correlation spectroscopy (DCS)), were employed to quantify cerebral blood flow (CBF) and oxygen metabolism (CMRO(2)) of 32 anesthetized CHD neonates at rest and during hypercapnia. Cerebral venous oxygen saturation (S(v)O(2)) and CBF were measured simultaneously with MRI in the superior sagittal sinus, yielding global oxygen extraction fraction (OEF) and global CMRO(2) in physiologic units. In addition, microvascular tissue oxygenation (StO(2)) and indices of microvascular CBF (BFI) and CMRO(2) (CMRO(2)(i)) in the frontal cortex were determined by DOS/DCS. Median resting-state MRI-measured OEF, CBF, and CMRO(2) were 0.38, 9.7 mL/minute per 100 g and 0.52 mL O(2)/minute per 100 g, respectively. These CBF and CMRO(2) values are lower than literature reports for healthy term neonates (which are sparse and quantified using different methods) and resemble values reported for premature infants. Comparison of MRI measurements of global S(v)O(2), CBF, and CMRO(2) with corresponding local DOS/DCS measurements demonstrated strong linear correlations (R(2)=0.69, 0.67, 0.67; P<0.001), permitting calibration of DOS/DCS indices. The results suggest that MRI and optics offer new tools to evaluate cerebral hemodynamics and metabolism in CHD neonates.

Risk factors for preoperative periventricular leukomalacia in term neonates with hypoplastic left heart syndrome are patient related.

BACKGROUND: Preoperative brain injury is common in neonates with complex congenital heart disease. Increasing evidence suggests a complex interaction of prenatal and postnatal risk factors for development of brain white matter injury, called periventricular leukomalacia (PVL), in neonates with complex congenital heart disease. To date, there remains a limited understanding of the risk factors contributing to preoperative PVL in hypoplastic left heart syndrome (HLHS). METHODS: Neonates with HLHS or HLHS variants from 3 prospective magnetic resonance imaging studies (2003-2010) were selected for this cohort. Preoperative brain magnetic resonance imaging was performed the morning of the surgery. Stepwise multilogistic regression of patient characteristics, mode of delivery (cesarean section vs vaginal), time of diagnosis (prenatal vs postnatal), HLHS subtypes, brain total maturation score, time to surgery, individual averaged daily preoperative blood gases, and complete blood cell count values was used to determine significant associations. RESULTS: A total of 57 neonates with HLHS were born at 38.7 ± 2.3 weeks; 86% (49/57) had a prenatal diagnosis, with 31% (18/57) delivered by cesarean section. HLHS with aortic atresia (AA) was common in this cohort, 71% (41/57). Preoperative PVL was identified in 19% (11/57). Male patients with AA (P = .004) were at higher risk for PVL. Lower total brain maturation score was also identified as a strong predictor for preoperative PVL (P = .005). CONCLUSIONS: In neonates with HLHS, nonmodifiable patient-related factors, including male sex with AA (lack of antegrade blood flow) and lower total brain maturation score, placed neonates at the greatest risk for preoperative white matter injury.

Sodium bicarbonate causes dose-dependent increases in cerebral blood flow in infants and children with single-ventricle physiology.

BACKGROUND: Sodium bicarbonate (NaHCO3) is a common treatment for metabolic acidemia; however, little definitive information exists regarding its treatment efficacy and cerebral hemodynamic effects. This pilot observational study quantifies relative changes in cerebral blood flow (ΔrCBF) and oxy- and deoxyhemoglobin concentrations (ΔHbO2 and ΔHb) due to bolus administration of NaHCO3 in patients with mild base deficits. METHODS: Infants and children with hypoplastic left heart syndrome (HLHS) were enrolled before cardiac surgery. NaHCO3 was given as needed for treatment of base deficit. Diffuse optical spectroscopies were used for 15 min postinjection to noninvasively monitor ΔHb, ΔHbO2, and ΔrCBF relative to baseline before NaHCO3 administration. RESULTS: Twenty-two anesthetized and mechanically ventilated patients with HLHS (aged 1 d to 4 y) received a median (interquartile range) dose of 1.1 (0.8, 1.8) mEq/kg NaHCO3 administered intravenously over 10-20 s to treat a median (interquartile range) base deficit of -4 (-6, -3) mEq/l. NaHCO3 caused significant dose-dependent increases in ΔrCBF; however, population-averaged ΔHb and ΔHbO2 as compared with those of controls were not significant. CONCLUSIONS: Dose-dependent increases in cerebral blood flow (CBF) caused by bolus administration of NaHCO3 are an important consideration in vulnerable populations wherein risk of rapid CBF fluctuations does not outweigh the benefit of treating a base deficit.