Aortic flow velocity by Doppler echo
Aortic flow is estimated by placing the Doppler cursor just beyond the aortic valve in the apical five chamber view. If the velocity is high as in aortic stenosis, continuous wave (CW) Doppler has to used to avoid aliasing. The gradient is calculated from the velocity (V) using the Bernoulli’s equation: Gradient = 4 V2. The calculation is automatically done by the machine software. A good estimate requires that the cursor and the jet has a parallel allignment. Angle correction can be applied using built in software in most echocardiographic machines if proper allignment is not possible. But the errors will be high if the mal-allignment is more than 20 degrees.