Color Doppler examination of the outflow tracts of the fetal heart: a technique for identification of cardiovascular malformations

Abstract

The objective was to describe a technique using color Doppler to identify the outflow tracts of the fetal heart by directing the ultrasound transversely through the fetal chest. One hundred second- and third-trimester control fetuses were examined with real-time and color Doppler ultrasound. The ultrasound beam was directed cephalad, in the same transverse plane used to image the four-chamber view, and the outflow tracts were examined. Four fetuses with abnormal cardiovascular anatomy were examined using the above approach, to study the anatomical relationships of the outflow tracts identified with color Doppler ultrasound in normal fetuses. When the ultrasound beam was directed immediately cephalad to the four-chamber view, the aorta was identified as it exited the left ventricle. Further movement of the ultrasound beam cephalad identified the following vessels in a single plane: the main pulmonary artery perpendicular to the ascending aorta; the left pulmonary artery branching from the main pulmonary artery; the full length of the ductus arteriosus; and the transverse arch of the aorta. The ascending aorta, main pulmonary artery, ductus arteriosus and transverse aortic arch were identified in 100% of fetuses. Four fetuses with abnormalities of the outflow tracts (aortic stenosis, aortic regurgitation, pulmonary stenosis and premature constriction of the ductus arteriosus) were imaged using this approach in which pathology was readily identified. This technique enables rapid identification of the outflow tracts in second- and third-trimester fetuses using color Doppler and accurately identifies abnormalities of these vessels.