[Hemodynamic consequences of portal decompression: which is the optimal shunt?]

Increased sinusoidal resistance in cirrhosis results in a decrease of the portal and a compensatory increase of the arterial blood supply to the liver. With increasing vascular resistance and development of extrahepatic collaterals stagnation and even reversion of the portal blood flow may occur. In the latter condition, the arterial blood leaves the liver through two routes: 1) through the sinusoids and the hepatic veins, and 2) through the portal vein. Experimental and clinical studies revealed that the arterio-portal pathway is metabolically inferior to the regular arterio-hepatic-venous pathway. This suggests a decrease in liver function with an increased incidence of hepatic encephalopathy (HE) in patients with reversed portal blood flow. Based on these findings, surgical shunts may be classified according to their effect on the arterial liver perfusion. The end-to-side shunt and the distal splenorenal shunt (DSRS) do not cause diversion of the arterial liver perfusion. In contrast, side-to-side shunts, with the portal vein available as an outflow tract, consistently lead to diversion of the arterial blood supply resulting in reversed portal blood flow. Thus, side-to-side shunts are supposed to have an increased incidence of HE due to decreased liver function. This hypothesis is supported by 7 controlled and randomized studies which reveal comparable results of end-to-side shunts and DSRS but significant disadvantages of side-to-side shunts compared to DSRS.