Social inequities impact infant mortality due to congenital heart disease.

OBJECTIVES: To evaluate how educational, economic, and racial residential segregation may impact congenital heart disease infant mortality (CHD-IM). STUDY DESIGN: This is a population-based US ecological study. METHODS: This study evaluated linked live birth-infant death files from the National Center for Health Statistics for live births from 2006 to 2018 with cause of death attributed to CHD. Maternal race and education data were obtained from the live birth-infant death files, and income data were obtained from the American Community Survey. A spatial social polarization measure termed the Index of Concentration at the Extremes (ICE) was calculated and split by quintiles for maternal education, household income, and race for all US counties (n = 3142). The lowest quintile represents counties with highest concentration of disadvantaged groups (income < $25K, non-Hispanic Black, no high school degree). Proximity to a pediatric cardiac center (PCC) was also analyzed in a categorical manner based on whether each county was in a metropolitan area with a US News and World Report top 50 ranked PCC, a lower ranked PCC, or not proximal to any PCC. RESULTS: Between 2006 and 2018, 17,489 infant deaths were due to CHD, an unadjusted CHD-IM of 0.33 deaths per 1000 live births. The risk of CHD-IM was 1.5 times greater among those in the lowest ICE-education quintile (0.41 [0.39-0.44] vs 0.28 deaths/1000 live births [0.27-0.29], P < 0.0001) and the lowest ICE-income quintile (0.44 [0.41-0.47] vs 0.29 [0.28-0.30], P < 0.0001) in comparison to those in the highest quintiles. CHD-IM increases with higher ICE-race value (counties with a higher concentration of non-Hispanic White mothers). However, after adjusting for proximity to a US News and World Report top 50 ranked PCC in the multivariable models, CHD-IM decreases with higher ICE-race value. CONCLUSIONS: Counties with the highest concentration of lower-educated mothers and the highest concentration of low-income households were associated with higher rates of CHD-IM. Mortality as a function of race is more complicated and requires further investigation.

Impact of congenital heart disease on cerebrovascular blood flow dynamics in the fetus.

OBJECTIVES: Neurological abnormalities are present in some children after repair of congenital heart disease (CHD). Recently, structural brain abnormalities have been identified in infants prior to cardiac surgery. By altering in utero blood flow patterns, the type of CHD may impact upon cerebrovascular flow dynamics prior to birth. We sought to determine whether left- and right-sided obstructive congenital heart lesions modify cerebrovascular flow dynamics in the fetus. METHODS: Pulsed Doppler was used to measure blood flow velocities in the umbilical (UA) and middle cerebral (MCA) arteries in 172 fetuses from 20 to 39 weeks' gestational age referred for fetal echocardiography. Pulsatility index (PI), an indicator of downstream vascular resistance, was determined by (peak systolic velocity--end-diastolic velocity)/mean velocity. RESULTS: Fetuses with hypoplastic left heart syndrome (HLHS; n = 28) had decreased MCA-PI (P = 0.009) compared to normal fetuses (n = 114). Fetuses with right-sided obstructive lesions (RSOL; n = 17) had increased MCA-PI (P = 0.001) when compared to fetuses with HLHS. The UA-PI was elevated in fetuses with RSOLs (P = 0.045). CONCLUSIONS: Cerebrovascular resistance is lower than normal in fetuses with HLHS, a condition in which cerebral perfusion occurs retrograde via the ductus arteriosus. Fetuses with RSOL had significantly higher cerebrovascular resistance compared to fetuses with HLHS. The type of CHD impacts upon fetal cerebrovascular blood flow distribution and this may have implications for later development of neurological sequelae.

Effects of beta-adrenergic antagonists on the QT measurements from exercise stress tests in pediatric patients with long QT syndrome.

It has been proposed that beta-adrenergic antagonist protection against cardiac events in patients with long QT syndrome (LQTS) may be related to a decrease in baseline QTc dispersion. To determine the effects of beta-blocker therapy on QT measurements, we evaluated the exercise tests of 25 pediatric patients with LQTS. Measurements were made of the maximum QTc interval and QTc dispersion during the various segments of the exercise test. There was no statistically significant difference between the pre-beta-blocker and post-beta-blocker maximum QTc interval during the supine (0.473 +/- 0.039 vs 0.470 +/- 0.038 sec), exercise (0.488 +/- 0.044 vs 0.500 +/- 0.026 sec), or recovery (0.490 +/- 0.031 vs 0.493 +/- 0.029 sec) phases of the exercise stress test. There was also no statistically significant difference between the pre-beta-blocker and post-beta-blocker QTc dispersion during the supine (0.047 +/- 0.021 vs 0.058 +/- 0.033 exercise vs 0.063 +/- 0.028 sec), or recovery (0.045 +/- 0.023 vs 0.052 +/- 0.026 sec) phases of the exercise stress test. Therefore, the protection that beta-blockers offer appears not to be related to a reduction of the baseline QTc interval or a decrease of QTc dispersion.