Distribution of hepatic venous blood in the total cavo-pulmonary connection: an in vitro study

Objectives: The objective of this project was to quantify the effects of ge ometry on the distribution of hepatic blood to the lungs in patients with a total cavo-pulmonary connection. The basis for this work is the suppositio n that hepatic blood is necessary for proper lung function. Methods: Plasti c models of these connections were made with varying degrees of offset betw een the inferior and superior vena cava and attached to an in vitro flow lo op. Dye was injected into the inferior vena cava and its concentration quan tified in each pulmonary artery. These data were converted to percentage co ncentration and distribution of hepatic blood to each lung. Results: With n o offset between the vena cava, hepatic blood distribution and concentratio n to each lung was similar to normal. For an offset of one or more diameter s, hepatic blood tended to flow preferentially towards the nearest pulmonar y artery with the opposite pulmonary artery exhibiting a deficit (<10% of n ormal). Conclusions: Distribution of hepatic blood to each lung was found t o be a function of vena cava offset and pulmonary artery flow split. Under normal conditions, 60% of blood towards the right pulmonary artery, the hep atic blood distribution to both lungs could be maintained above 50% of norm al if the inferior vena cava was offset towards the left pulmonary artery. Offsetting the inferior vena cava towards the right pulmonary artery jeopar dized the delivery of hepatic blood to one lung. (C) 2000 Elsevier Science B.V. All rights reserved.