A - atrial systole - retrograde wave
S - ventricular systole - antegrade wave
V- opening of tricuspid valve - retrograde wave
D - right ventricular diastolic filling - antegrade wave
The hepatic vein Doppler shows tetraphasic waveform with reduced systolic (S) velocity with a systolic/diastolic (S/D) velocity ratio <1 due to reduction in RV longitudinal motion. This suggests pulmonary hypertension with right ventricular systolic dysfunction.
Note the normal increase in forward flow during inspiration with persistent S/D ratio <1.
The diastolic (D) waveform is prominent despite the presence of pulmonary hypertension.