Intraoperative ultrasonography of the portal vein during attenuation of intrahepatic portocaval shunts in dogs

A method for intraoperative measurement of portal blood flow velocity with duplex Doppler ultrasonography in 7 dogs with congenital intrahepatic portosystemic shunts is described. The aims of the study were to determine whether intraoperative ultrasonography was an acceptable alternative to mesenteric portography in such dogs and to identify quantitative portal hemodynamic variables that might correlate with clinical outcome better than portal pressure does. Ultrasonographic measurements did not influence decision-making by the surgeon, who attenuated the shunt on the basis of appearance of the viscera and change in mean systemic arterial blood pressure. All dogs recovered without complications, and surgery was considered to be successful in all 7. Intraoperative B-mode ultrasonography provided real-time information about the anatomy of the shunt and the portal branches, suggesting that it may be a useful alternative to mesenteric portography. The time-averaged mean portal blood velocity ranged from 6.5 to 33.7 cm/s before shunt attenuation and from 5.0 to 9.5 cm/s after shunt attenuation. This narrow range of postligation velocities suggested that intraoperative ultrasonography might be an alternative to intraoperative portal pressure measurement.