Liver Doppler Ultrasound - Pulsatility in Portal Vein Flow
The flow pattern in the portal vein is usually monophasic with a near constant velocity throughout the cardiac cycle (Fig. 1 and 2).
Fig. 1. A normal monophasic portal vein flow pattern.
Fig. 2. Another example of normal flow in the portal vein.
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).
Fig. 3. Pulsatile portal vein flow.
Fig. 4. Increased pulsatility in a patient with tricuspid regurgitation.
Occasionally the whole central venous phasicity is transmitted across the sinusoids resulting in a tetrainflectional, triphasic flow pattern in the portal vein (Fig. 5).
Fig. 5. Triphasic, tetrainflectional flow in the portal vein caused by severe right-heart failure.
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).
Fig. 6. Portal vein flow shown in figure 5 (upper part) and its mirror image (lower part), which perfectly matches a central venous flow pattern typical of right-sided heart failure +/- tricuspid regurgitation. The flow waves are labeled in accordance to central venous pressure wave nomenclature.
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- 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.