Computer analysis of portal hemodynamics after small-diameter portacaval H-grafts: the theoretical basis for partial shunting.
We have previously reported on the clinical results of partial shunting using small-diameter portacaval H-grafts. In this study, we defined the theoretical basis for partial shunting using the Wheatstone bridge model of the splanchnic circulation. The model was modified to include a variable resistance for a portacaval shunt and was programmed as a computer simulation. We calculated portal flow as a function of shunt resistance to determine the resistance necessary to maintain prograde portal flow in patients with portal hypertension. The resistance of 8- and 10-mm portacaval H-grafts, as positioned clinically, was determined using a laboratory apparatus. The experimentally derived values for resistance were inserted into the graph of portal flow predicted by the computer program. Portacaval H-grafts 8 mm in diameter should produce prograde portal flow, 10-mm H-grafts should be borderline, and shunts larger than 10 mm should routinely result in reversed flow. These predictions were confirmed by clinical observations in 29 patients undergoing portacaval H-grafts.
D003198:Computer Simulation; D004932:Esophageal and Gastric Varices / Q000601:surgery; D006801:Humans; D006975:Hypertension, Portal / Q000503:physiopathology; D011167:Portacaval Shunt, Surgical / Q000379:methods; D011168:Portal System / Q000502:physiology*; D013152:Splanchnic Circulation; D014655:Vascular Resistance