Normal hepatic spectral Doppler waveforms
The normal hepatic artery has a rapid systolic upstroke and continuous diastolic flow. The normal portal veins have continuous hepatopedal (toward the liver) flow with mild phasicity due to respiratory and cardiac activity. Normal portal vein velocity is approximately 20 cm/sec. Due to proximity to the heart, the normal hepatic veins have multiphasic waveforms secondary to transmitted cardiac pulsation with prominent antegrade systolic and diastolic waves, with small retrograde waves after both systole and diastole reflecting right atrial overfilling against a closed tricuspid valve after systole and atrial contraction after diastole.