Effect of Portal Blood Flow and Intra-Arterially Injected Starch Microspheres on the Passage of a Labelled Tracer Through the Liver: An experimental study in pigs

Pig liver was used to study the influence of portal blood flow and degradable starch microspheres (DSM) on the passage of radiolabelled methylene-di-phosphonate from the hepatic artery to the systemic circulation. When the portal vein was clamped abut 70 per cent of the labelled marker injected into the hepatic artery passed to the systemic circulation and the remaining 30 per cent passed when the portal vein was opened. When the flow of the hepatic artery was stopped, the portal blood flow alone drained about 65 per cent of the marker, which was given as a small volume injection into the hepatic artery. When both the arterial perfusion and the portal blood flow were closed the marker only slowly passed to the systemic circulation. DSM injected into the hepatic artery reduced the passage of the marker through the liver to 75 per cent of the reference level when the portal vein was open. When it was clamped this figure was reduced to about 25 per cent. The effect of DSM on the passage of the labelled marker was found to be dose dependent. It is suggested that the reduced passage of a labelled tracer given mixed with DSM is a useful measure of degree of arterial occlusion in the liver. However, because of the drainage via the portal system the passage cannot be completely inhibited.