Sonograms of the fetus of coarctation of the aorta at the four-chamber view. The four-chamber view shows symmetrical left and right chambers. In addition, a bidirectional shunt (indicated by the arrows) between the left and right ventricles is demonstrated by color Doppler. DA: ductus arteriosus; DAO: descending aorta; L: left; LA: left atrium; LV: left ventricle; R: right; RA: right atrium; RV: right ventricle; SP: spine