Intrahepatic portosystemic venous shunt: diagnosis by color Doppler imaging.

Intrahepatic portosystemic venous shunt is a rare clinical entity; only 33 such cases have been reported. It may be congenital, or secondary to portal hypertension. Five patients with this disorder are presented, each of whom was diagnosed by color Doppler imaging, including waveform spectral analysis. One patient with clinical evidence of cirrhosis and portal hypertension had episodes of hepatic encephalopathy and elevated blood levels of ammonia. This patient had a large tubular shunt between the posterior branch of the portal vein and the inferior vena cava. Shunts of this type are considered to be collateral pathways which develop in the hepatic parenchyma as a result of portal hypertension. The other four patients had no evidence of liver disease, and all four evidenced an aneurysmal portohepatic venous shunt within the liver parenchyma. Shunts of this type are considered congenital. The diagnosis of intrahepatic portosystemic venous shunts was established by color Doppler imaging, which demonstrated a direct communication of color flow signals between the portal vein and hepatic vein, in addition to the characterization of the Doppler spectrum at each sampling point from a continuous waveform signal (portal vein) to a turbulent signal (aneurysmal cavity), and finally, to a biphasic waveform signal (hepatic vein). As demonstrated by the five patients, color Doppler imaging is useful in the diagnosis of an intrahepatic portosystemic hepatic venous shunt, and the measurement of shunt ratio may be useful in the follow-up and determining the therapeutic option.