156: Changes in the shape of the heart of growth-restricted fetuses in relation to peripheral hemodynamic deterioration

To evaluate dynamic changes in the shape of the heart in growth-restricted fetuses. A total of 80 fetuses with an estimated fetal weight <10th percentile for gestational age were evaluated; 38 with umbilical artery pulsatility index (UA-PI) >95th percentile but with still-present positive end-diastolic velocities and 42 with absent or reversed end-diastolic velocities (ARED) in the umbilical artery. A video sequence of the cardiac cycle obtained at the 4-chamber view was obtained. The global sphericity index (GSI) was calculated at end-diastole by computing the ratio between two perpendicular measurements: the basal-apical and transverse lengths of the 4-chamber view (Figure 1). These measurements included all of the structures (walls and chambers) and were measured from epicardial to epicardial borders. End-diastole was determined by reviewing each frame of the video sequence until the first downward systolic motion at the junction of the annulus of the tricuspid or mitral valve occurred. When this frame was identified, the frame before was chosen to represent end-diastole. Differences in the GSI measurement and the GSI z-scores between the two groups were analyzed using the Student T test. Fetuses with ARED in the umbilical artery showed a significantly lower GSI (1.07 (SD 0.11); z-scores -1.66) than fetuses with UA-PI>95th percentile but who still had positive end-diastolic velocities (GSI=1.15 (SD 0.11); z-scores -0.86). Figures 2a and 2b show differences in GSI (p=0.004) and GSI Z-scores p=0.003) between the two groups, respectively. Either as an adaptive process or as a consequence, the heart of growth-restricted fetuses modifies its shape as the peripheral vascular resistance increases. The hearts of growth-restricted fetuses with ARED in the umbilical artery are more globular than those from fetuses with end-diastolic velocities still present in the umbilical artery. If the GSI is used as a simple screening tool to identify fetuses with abnormal globular instead of normal ellipsoid-shaped hearts, further investigation using more sophisticated techniques would be warranted to investigate which specific cardiac structures (chambers, walls) are involved in reshaping the 4-chamber view of the fetal heart.View Large Image Figure ViewerDownload Hi-res image Download (PPT)