It consists in an anastomosis Between the portal vein and the Interior vena-cava, when the portal Blood is deviated from the vena-cava The pressure over the portal system Is diminished and danger from Hemorrhage from esophagus And gastric varicosity is reduced When the vena-cava can not be Used because of an obstruction by Thrombosis or any other reason One proceeds by a spleen-renal Deviation between the spleen Vena and the renal left vena