Mechanical pumping of portal blood to the liver: hemodynamic effects of a new experimental treatment for portal hypertension

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Background/Aims: It has been suggested that mechanical pumping of portal blood to the liver may correct portal hypertension while increasing portal flow to the liver, which may enhance liver function in cirrhosis. However, the hemodynamic effects of this procedure are unknown. The present study investigated these issues in rats with portal hypertension due to portal vein stenosis. Methods: Mechanical pumping of portal blood to the liver was established by an extracorporeal shunt bypassing the portal vein stenosis, connected to a continuous withdrawal/infusion pump. Portal pressure, portal-systemic shunting (mesenteric injection of Cr-51 microspheres, n=10), mesenteric artery blood flow (perivascular Transonic flowmeter, n=7) and systemic hemodynamics and regional blood flows (left ventricle injection of Ce-141 microspheres, n=15), were measured at pumping rates of 0, 3 and 6 ml·min −1. Results: Mechanical pumping of portal blood to the liver caused a marked decrease in portal pressure (from 17±1 to 12.6±1 and 9.4±.9 mmHg at pumping rates of 0, 3 and 6 ml·min −1) and portal-systemic shunting (from 97±4 to 70±4 and 51±6% respectively) ( p<0.001). However, there were no significant changes in mesenteric artery flow (5.5±3 vs 5.6±3 ml·min −1·100 g −1), suggesting that all blood pumped to the liver was withdrawn from that circulating through the collaterals. Moreover, there were no changes in mean arterial pressure, cardiac index, peripheral resistance and splanchnic arteriolar resistance. Conclusions: The short-term mechanical pumping of portal blood to the liver effectively decreases portal pressure and portal-systemic shunting and has no significant effects on systemic and splanchnic hemodynamics in portal hypertensive rats.