ABSTRACT
Echocardiography is a combination of complementary techniques. These techniques are
two-dimensional echocardiography and Doppler ultrasound. Two-dimensional echocar-
diography displays three-dimensional structures in a two-dimensional format. It is an
excellent method to interrogate anatomical structures. Fortunately, the high resolution of
today’s echocardiography technology enables very detailed examination of cardiac
anatomy. Although two-dimensional echocardiography reveals much information about
anatomy, it provides no information about blood flow and the forces associated with this
flow. Doppler ultrasound provides this information. Doppler ultrasound is used to
examine blood flow in terms of direction, velocity, and pattern of flow. It is a quantitative
process and can be used as a means of grading disease severity. Two-dimensional
echocardiography, on the other hand, can be used to diagnosis the disease itself. Two-
dimensional echocardiography and Doppler ultrasound are complementary in that the first
is used to evaluate structure and the second is used to evaluate function. Understanding
the value and limitations of Doppler ultrasound is essential to understanding the
diagnostic utility of ultrasound as a whole.