Detailed assessment of fetal ventricular septal defect with 4D color Doppler ultrasound using spatio‐temporal image correlation technology

A 25-year-old woman, gravida 2 para 1, presented at 23 weeks' gestation for detailed targeted organ scanning with fetal echocardiography, after having received contradictory opinions concerning a suspected ventricular septal defect (VSD) during previous ultrasound examinations. The parents reported no family history of congenital heart malformation. Targeted organ scanning for exclusion of fetal anomalies was performed, including complete fetal echocardiography as described previously1. Two-dimensional gray-scale and color Doppler mapping raised the suspicion of VSD, but the flow was detected only at intervals, and the defect was apparent only at certain angles of insonation. Three- and four-dimensional spatio-temporal image correlation (STIC) technology2 was applied: Figure 1a shows the resulting multiplanar image depicting the fetal heart in three orthogonal views with color Doppler. Figure 1b shows the four-chamber view in surface rendering mode with an apparently intact septum, although a ‘crater’ appears on the left ventricular face of the septum where it appears thinner. Figure 1c shows rendering mode with color Doppler obtained by progressing frame-by-frame through the acquired cardiac cycle. The blue jet shows shunting of the blood through the VSD during diastole. Figure 1d is, to the best of our knowledge, the first publication of a lateral view of the septum and VSD. The entire area of the septum is visualized intraventricularly from the left chamber, and the VSD highlighted by blue Doppler flow mapping. These views reveal the VSD in its entirety and allow, for the first time, measurement of the area of the defect. The two images characterize the spatial and temporal nature of the defect and of the shunt during the cardiac cycle. Figure 1e confirms the absence of flow during systole: flow is apparent in the left ventricular outflow tract (red) but not through the VSD. These images emphasize the temporal changes in pressure gradient between the heart ventricles through the cardiac cycle; the gradient is not necessarily greater during systole. (a) Multiplanar with color Doppler images of the fetal heart in three orthogonal views, with blood shunting across the ventricular septal defect (VSD) in the upper left image. (b) Surface-rendered image of the fetal heart in apical four-chamber view. The arrow indicates the apex. The interventricular septum (IVS) appears intact. (c) Surface-rendered image with color Doppler mapping showing blood shunting through the VSD. (d) Surface rendered image with color Doppler mapping on lateral view of the IVS and VSD. (e) Color Doppler mapping of the fetal heart in systole; note the red flow in the left ventricular outflow tract (lvot). ao, aorta; la, left atrium; lv, left ventricle; ra, right atrium; rv, right ventricle. This case of isolated VSD in a 23-week fetus demonstrates the added power of STIC technology when used in tandem with color Doppler 3D and surface rendering in fetal echocardiography. Application of this modality allowed measurement of the area of the defect, its spatial location in the septum and its temporal location in the cardiac cycle. An additional value of this modality may be the easier detection and evaluation of multiple VSDs, also known as ‘Swiss cheese septum’.