Understanding the Pathophysiology of Portosystemic Shunt by Simulation Using an Electric Circuit

Abstract

Portosystemic shunt (PSS) without a definable cause is a rare condition, and most of the studies on this topic are small series or based on case reports. Moreover, no firm agreement has been reached on the definition and classification of various forms of PSS, which makes it difficult to compare and analyze the management. The blood flow can be seen very similar to an electric current, governed by Ohm's law. The simulation of PSS using an electric circuit, combined with the interpretation of reported management results, can provide intuitive insights into the underlying mechanism of PSS development. In this article, we have built a model of PSS using electric circuit symbols and explained clinical manifestations as well as the possible mechanisms underlying a PSS formation.

Figure 1

Schematic diagram of abdominal vascular connections ignoring spatial relations. The portal system is depicted by purple lines. Any abnormal connection between the portal system and the systemic veins can form a shunt circuit (dotted line). Note that collaterals between aortic branches are omitted. CA: celiac artery. SMA: superior mesenteric artery. IMA: inferior mesenteric artery. IMV: inferior mesenteric vein. SMV: superior mesenteric vein. PV: portal vein. SV: splenic vein. HV: hepatic vein. ⓐ, ⓑ, and ⓒ: possible shunt occlusion sites.

Figure 2

Electric circuit diagram simulating a portosystemic shunt. V _AO: aortic pressure. V _PV: portal pressure. V _IVC: systemic venous pressure. I _M: mesenteric flow. I _P: portal flow. I _S: shunt flow. R _M: resistance of mesenteric vessels. R _L: resistance of intrahepatic portal vasculature. R _S: resistance of shunt. ⓐ, ⓑ, and ⓒ: possible shunt occlusion sites.