Measurement of Blood Flow in the Collateral Vessels of the Portal Vein; Preliminary Results of a New Method

The portal vein and its branches may be demon-strated by the intrasplenic injection of radiocon-trast media. Such identification of collateral ves-sels aids understanding of some of the symptoms of chronic liver disease (1-4). The size and lo-cation of collateral vessels is shown; however, the blood flow through them is not measured. Cer-tain syndromes, such as the neurological complica-tions of chronic liver disease (portal systemic en-cephalopathy), depend more on the total collateral blood flow than on the presence of any specific col-lateral vessels (5). This paper reports a method for measuring the portal collateral blood flow and its application in 12 patients. If an indicator substance is introduced into, and is rapidly absorbed from the spleen, part of it reaches the general circulation by passing through the liver and the remainder by passing through any collateral channels present (Figure 1). The amount passing by each of the two routes is di-rectly proportional to its respective blood flow. The amount passing through the liver is measured from the concentration of the indicator in the he-patic venous blood and the blood flow through the liver. Some indicator recirculates to the portal vein by way of the arteries and is measured in the femoral artery. When absorption is com-plete the total amount of the indicator absorbed may be determined from the product of its con-centration and its volume of distribution. During the time required to reach equilibrium, the difference between the amount of radioactivity leaving the splanchnic bed and the amount enter-ing should be equal to the effective radioactivity