Application of multigate pulsed Doppler systems in congenital heart disease

Abstract

Single gate pulsed Doppler systems enable the transcutaneous investigation of the hemodynamic behavior at a rather well determined site. The spatial resolution of pulsed Doppler systems in both axial and lateral direction with respect to the ultrasound beam provides a means to emphasize specific phenomena without interference caused by Doppler signals originating from outside the sample volume. However, a single gate system obscures the three-dimensional nature of blood flow in the cavities of the heart. A multigate pulsed Doppler system allows the assessment of the hemodynamic behaviour in a number of sample volumes simultaneously. Preferable a large number of sample volumes of small dimensions hould be employed to maintain detail in the velocity distribution along the ultrasound beam. To provide feedback about the position of the ultrasound beam with respect to the structures investigated a multigate pulsed Doppler system should be connected to a two-dimensional imaging system. Operating alternately the echo- and the Doppler system allows verification of the position of the ultrasound beam intermittently.