872 Racial differences in spiral artery remodeling

Abstract

Maternal race is a determinant of the frequency and severity of ischemic placental disease. Current Doppler methods infer, but do not directly assess, function of the spiral arteries (SA), the root of placental dysfunction. We developed a novel ultrasound method combining B-flow, spatiotemporal image correlation (STIC) and M-Mode to image and measure SA intraluminal diameter during the maternal cardiac cycle in both systole (S) and diastole (D)(Fig 1). We tested the hypothesis that measurable SA function differs between races. In an IRB-approved prospective longitudinal observational study, we defined a supernormal population (parity=0, no co-morbidities or pregnancy complications) to control covariables. S and D were quantified in all trimesters, with a compound ultrasound technique: In B-flow mode, STIC/4D image blocks of individual SA were acquired systematically in the placental bed. S and D diameters were measured via M-Mode. At the first trimester visit, serum analytes (PAPP-A, PlGF, AFP) were obtained. At each visit, BMI, mean arterial blood pressure, mean uterine artery-PI, gestational age (GA), race and age were recorded. Quality control included formal training, written criteria for image acceptance and screening of every image by senior study personnel, all blinded to patient characteristics/outcome. Longitudinal analysis utilized a linear mixed-effects model with random intercept and random slope. A total of 645 SA were measured serially in 43 women (15 each) at 11-32 weeks. Women self-assigned race as Black (24), White (14) or Asian (5). S and D diameters rose with GA (p<0.001 for both). S was significantly higher in W than B and A (Fig 2) The model showed significant interaction between S and PAPP-A (p<0.0001). The study shows B-flow/M-mode can detect and quantify SA remodeling and illustrates the normal loss of mural tone of these vessels as pregnancy advances. Even when pregnancy outcome is normal, black women show less remodeling, a potential clue to their liability for placental dysfunction across pregnancy and the puerperium.View Large Image Figure ViewerDownload Hi-res image Download (PPT)