In what conditions are descending aortic flow reversal seen on Doppler echo?

In what conditions are descending aortic flow reversal seen on Doppler echo?

Descending aortic flow reversal can be noted in aortic regurgitation, rupture of sinus of Valsalva into right ventricle and patent ductus arteriosus. It may be noted that transient descending thoracic aortic flow reversal may be detectable by Doppler echo without any of these conditions.

When the aortic wall is stiff as in hypertensives with atherosclerosis, transient flow reversal is thought to be one mechanism for cerebral embolism from aortic plaques beyond the origin of cerebral vessels.

In severe aortic regurgitation it is a pan diastolic flow reversal with end diastolic velocity more than 20 cm/s. It is taken as an indirect evidence of severe aortic regurgitation on echocardiography.