Abstract 17390: Maternal and Fetal Cardiovascular Adaptations to Pregnancy and Outcomes in Mothers With Cardiac Disease - A Magnetic Resonance Imaging Study

Abstract

Introduction: Insufficient maternal cardiac output (CO) has been implicated in poor pregnancy outcomes in mothers with heart disease (HD). Simultaneous delineation of vascular flows in the mother and her fetus have not been reported but could contribute to our understanding of the mechanisms of adverse events in this susceptible population. Methods: Pregnant women with moderate or severe HD (n=22; age 32±5 years) were studied using magnetic resonance imaging (MRI) and were compared with healthy controls (n=21; 34±3 years). Each MRI study included maternal and fetal components during the third trimester of pregnancy (corresponding to peak CO) and six months postpartum (surrogate for baseline hemodynamics). Phase contrast (PC) imaging was used to quantify maternal and fetal vascular flows. Fetal vessel T1 and T2 oximetry was used for derivation of fetal oxygen delivery and consumption. Maternal cardiac index (CI) was calculated using CO and pre-pregnancy body surface area. In the HD group, an “adapter” to pregnancy was defined as a woman with peak pregnancy CI measurement which met or exceeded the mean CI in the control population. Maternal and fetal outcomes were recorded. Results: There was no antepartum differences in absolute CO or CI in HD versus controls (CO 7.2±1.5 versus 7.3±1.6 L/min, p=0.79; CI 4.0±0.7 versus 4.3±0.7 L/min/m 2 , p=0.28). The percent increase in CO and CI (antepartum minus postpartum) was greater in women with HD versus controls (CO 46±24% versus 27±16%, p=0.02; CI 51±28% versus 28±17%, p<0.01). Fetal growth and oxygen delivery/consumption were similar between groups. Six adverse maternal cardiovascular events occurred in the HD group (heart failure n=2 and arrhythmia n=4) and there were none in the control group. There were no adverse fetal events in either group. There were 6 HD adapters (30%) and the adverse event rate was lower as compared with non-adapters (0% versus 38%, p=0.03). Conclusions: Maternal and fetal vascular flows can be characterized in pregnancy using MRI. Impaired adaptation to pregnancy in women with HD, as determined by magnitude of change in CO/CI, appears to be associated with adverse outcomes of pregnancy in the mother.