The flow pattern in the portal vein is usually monophasic with a near constant velocity throughout the cardiac cycle (Fig. 1 and 2).
Decreased compliance of the liver vascular bed and/or increases in blood volume flow to the liver lead to enhanced pulsatility in portal vein flow. Common reasons include cirrhosis of the liver, right-sided CHF and tricuspid regurgitation (1).
Increased pulsatility usually takes the form of an undulating waveform with one dip and one peak per cardiac cycle (Fig. 3 and 4).
Occasionally the whole central venous phasicity is transmitted across the sinusoids resulting in a tetrainflectional, triphasic flow pattern in the portal vein (Fig. 5).
Mirroring this waveform around the baseline (Fig. 6) results in a perfect depiction of a central venous flow pattern, in this case with a relatively blunted systolic (X) and a prominent diastolic (Y) descent typical of right-sided heart failure and/or tricuspid regurgitation (2).
- McNaughton DA, Abu-Yousef MM. Doppler US of the liver made simple. RadioGraphics. 2011;31(1):161–188. doi:10.1148/rg.311105093.
- Scheinfeld MH, Bilali A, Koenigsberg M. Understanding the spectral Doppler Waveform of the Hepatic veins in health and disease. RadioGraphics. 2009;29(7):2081–2098. doi:10.1148/rg.297095715.