Diagnosis and assessment of valve stenosis and regurgitation and coarctation of the aorta with Doppler ultrasound.

With the use of Doppler ultrasound localized increases in blood flow velocities can be recorded and used to diagnose obstructions to blood flow. From the increase in maximal velocities the pressure drop across an obstruction can be calculated, both the peak instantaneous and the mean pressure drop. Regurgitations are diagnosed by recording reversal of blood flow across the valve. Semi-quantitative evaluation of the degree of regurgitation can be made by using both jet width, extension and intensity, as well as increase in forward flow velocity, reversal of flow in great vessels and influence on pressures. In coarctation of the aorta localized increase in velocity in the descending aorta can be shown and the pressure drop can be calculated. In some, more than one level of obstruction can be shown. In neonates the presence of a patent ductus arteriosus may mask the obstruction and a significant pressure drop may become apparent only when narrowing or closure of the duct occurs.