455: Fetal growth restriction cardiac dysfunction is independent of Doppler indices

Abstract

The ventricular sphericity index, a ratio of ventricular length divided by ventricular width, is used to assess cardiac function. Cardiac dysfunction, even affecting only one ventricle, results in an increase in overall heart size and a more globular shape. In a previous study, we found a higher rate of abnormal shape, assessed by global sphericity index (GSI), and increased cardiac area (CA) in fetuses with fetal growth restriction (FGR). In the current study, we hypothesized that these measures of cardiac dysfunction in FGR would relate to abnormal Doppler findings. 46 fetuses with estimated fetal weight (EFW) <10th percentile were studied serially. Using 2-D real time clips, GSI was calculated from the 4-chamber view at ventricular end diastole. Measurements were obtained from the epicardial borders at the widest transverse diameter (TL) and the longest basal/apical length (BAL) (Image). CA was calculated using the same two measurements (TL and BAL). Based on prior studies, a GSI of <1.08 and CA >90th% are considered abnormal. Umbilical artery (UA) PIs and middle cerebral artery (MCA) PIs were determined to be abnormal or normal by available nomograms. GSI and CA percentiles based on EFW (grams) were compared in a cross-sectional gestational age range (31-35 weeks), and analyzed with an unpaired t-test or Chi squared. 10 fetuses (21%) had abnormal GSIs and 21 (45%) had abnormal CAs. There were no significant differences between normal and abnormal UA groups in either GSI (1.16 ± 0.016, n=32 vs 1.15 ± 0.033, n=14; p=0.7681) or CA (88.94 ± 4.18, n=32 vs 93.4± 9.37, n=14; p=0.44). Similarly, GSI (1.16 ± 0.017, n=30 vs 1.15 ± 0.027, n=16; p=0.42) and CA (92.7 ± 4.81, n=30 vs 76.73 ± 6.98, n=16; p=0.302) values did not differ between normal and abnormal MCA. A comparison of percentages of abnormal GSI (<1.08) and CA (>90th%), showed no differences between normal and abnormal UA or MCA. While CA and abnormal GSI are increased in FGR compared to average for gestational age controls, there does not appear to be a Doppler dependent difference within our cohort. This suggests that the fetal heart responds to FGR in a way that cannot be predicted by measures of placental resistance or brain sparing, and could be used as an independent predictor of fetal compromise.