How can echocardiography be used to estimate the severity of aortic insufficiency?

As in mitral regurgitation, there are various ways to estimate the severity of aortic insufficiency using echocardiography:
1. Estimate the jet size at the regurgitant orifice using color flow Doppler. This method is even less reliable in aortic insufficiency than in mitral regurgitation because the size of the jet in aortic insufficiency also depends on the left ventricular end-diastolic pressure and the systemic vascular resistance.
2. Measure the width of the regurgitant jet at the level of the valve orifice using 2DE (best seen in the parasternal short axis).
3. Calculate the P1/2. Contrary to the situation with mitral stenosis, the shorter the P1/2, the more severe the regurgitation. A short P1/2 reflects a rapid equilibration of pressures between the left ventricle and aorta.