Objectives: "Heart sparing" refers to prominent antegrade fetal coronary artery (CA) blood flow readily visualized by color Doppler and is a harbinger of poor outcome in growth restricted fetus, but little is known of the features and presentation of heart sparing in normally grown fetuses. Our objective was to describe heart sparing effects in normally grown fetuses, and compare the presentation and outcome of heart sparing between fetuses with growth restriction and those who were normally grown.
Methods: In a series of fetuses with prominent antegrade CA flow, we assessed Doppler flow profiles in the aortic isthmus, ductus venosus (DV), umbilical vein (UV), umbilical artery (UA) and middle cerebral artery (MCA). We calculated MCA and UA systolic/diastolic ratios and the cerebral placental ratio, and measured fetal biometry. We evaluated cardiac function using the myocardial performance index (MPI) and the cardiovascular profile score (CVPS).
Results: Ten fetuses with heart sparing had normal DV flow at 24-36.6 (mean 30.9) weeks of gestation. Five had growth restriction (Group 1); 4/5 had normal MPI and CVPS, and one died. Five were normally grown (Group 2); 5/5 had elevated MPI and decreased CVPS, of these 2 died in utero and one died immediately after birth despite urgent delivery. Coronary arteries were normal after birth or autopsy.
Conclusions: Heart sparing confers a poor prognosis in fetal growth restriction and in normally grown fetuses with cardiac dysfunction. We suggest CA flow be assessed in all high-risk fetuses.
Keywords: Cardiomyopathy; coronary blood flow; fetal growth restriction; fetus; heart sparing.