Diastolic flow reversal in the descending abdominal aorta in aortic regurgitation

Using a subcostal window, just to the left of the midline, the pulse wave Doppler (PWD) sample volume from the abdominal aorta (ABAO) viewed in its long axis (panel A). In severe aortic regurgitation, the reverse diastolic flow component is almost equal in size to the forward flow signal (panel B). However, the net forward flow is actually greater than the reversed flow because the diameter of the aorta in systole is much larger than in diastole, due to augmented pulsitility. In the normal subject, diastolic flow in the aorta is minimal (panel C); there is a prominent forward flow signal above the baseline and a small and brief signal of reversed diastolic flow below (arrows).