Current development in Doppler echocardiography. The real-time two-dimensional Doppler flow imaging system.

Recent advances in ultrasound instrumentations have provided a new Doppler modality capable of displaying the spatial distribution of blood flow velocities by colors on the monochromatic echo image on the real time basis, called the real-time two-dimensional Doppler flow imaging system. With this new Doppler technique, we can noninvasively relate the dynamic flow pattern to the anatomy and the motion of the cardiac structures and can further our understandings of flow dynamics in the circulatory system in health and disease. In clinical cardiology, the Doppler flow imaging technique offeres a quite sensitive approach to the detection of flow abnormalities caused by valvular insufficiency or stenosis and congenital shunt diseases. The spatial distribution of the regurgitant jet flow visualized by the Doppler flow imaging technique provides a semiquantitative approach to the evaluation of the severity of the valvular insufficiency. Furthermore, we can appreciate the spatial and angular orientation of the stenotic or regurgitant jet flow, which allows us to measure the velocity of the jet flow with the optimal beam direction. Though there are some limitations and pitfalls in the Doppler flow imaging system at present, it has provided the mapping of the dynamic distribution of flow velocities, which has never been available with the conventional Doppler technique, and has expanded Doppler capabilities and utilities in clinical cardiology. The Doppler flow imaging system is now widely used as a routine part of noninvasive cardiac examination and is improving its clinical significance.