Color Doppler sonography to evaluate transjugular intrahepatic portacaval stent shunt

Changes in hepatic perfusion after administration of hydroxyethyl starch in intensive care patients assessed using color-coded Doppler sonography

Using color-coded Doppler sonography (CCDS), changes in the resistance index of the hepatic artery (HA-RI) and in the velocities of the hepatic artery, portal and splenic vein (HA-V, PV-V, SV-V) were measured after administration of hydroxyethyl starch (HES) in 50 intensive care patients. PV-V and SV-V increased, whereas HA-V and HA-RI remained unchanged. CCDS is suitable to assess liver perfusion in intensive care patients. Since HES enhances splanchnic perfusion, its application improves hepatic perfusion in intensive care patients.

The hemodynamics of transjugular intrahepatic portosystemic shunts: investigations with Doppler sonography and development of an in vitro model

RATIONALE AND OBJECTIVES

We evaluated Doppler sonography-based measurements of transjugular intrahepatic portosystemic shunt (TIPS) function and developed an in vitro model of normal TIPS hemodynamics.

METHODS

We reviewed retrospectively the results of all trans-TIPS manometries (N = 116) performed during a 24-month period. Portosystemic pressure gradient was compared with peak stent velocity as measured by angle-corrected Doppler sonography. A flow phantom simulating TIPS was created using 8-, 10-, and 12-mm-diameter wire-mesh stents placed in cylindrical channels with lengths ranging from 3.4 to 6.0 cm.

RESULTS

Among 50 trans-TIPS manometries with corresponding Doppler sonography performed on well-functioning shunts, measured portosystemic pressure gradient and peak velocity were not correlated (R2 = .014). On the basis of a regression of measurements in the flow phantom, pressure loss in a stented cylindrical channel was estimated as follows: delta p = rho.(0.145 -0.001.Rey + 0.816.L/D).(Vmean2/2), where rho is the fluid density, Rey is the Reynolds number, L is the channel length, D is the stent diameter, and Vmean is the time-averaged velocity within the stent. Predicted and measured pressure gradients were correlated (R2 = .91).

CONCLUSION

Peak velocity in patients with a normally functioning TIPS does not predict the magnitude of the portosystemic pressure gradient.