Continuous Wave Doppler:
©Walter Rasmussen, R.D.C.S.
In continuous wave Doppler mode, blood flow is sampled along the entire length of the ultrasound beam, superimposing all encountered forward flow and reverse flow on the spectral Doppler graph.
The advantage of CW Doppler is that it can record much higher velocities than PW Doppler because the Doppler signal is not pulsed and does not have to interrupt the signal in order to receive the blood flow information. The disadvantage of CW Doppler is that it cannot indicate at what depth the displayed velocity is located and therefore is best used in combination with two-dimensional imaging and color Doppler in order to make certain that no other high velocity blood flow can be confused with the intended target.
The uses of CW Doppler for echocardiography will be discussed in detail as it applies.