Hepatic blood flow after canine portasystemic shunting.

Effects of portasystemic shunting on total hepatic blood flow (THBF) were evaluated in mongrel dogs with 35 and 50micro radioactive microspheres. THBF was measured prior to shunting and 1 hour and 3 weeks after surgery. Using systemic and pulmonary artery catheters, pertinent hemodynamic variables were also measured. In sham-operated dogs (n = 5), there were no significant changes in the hemodynamic parameters or the components of THBF during the experiment. After end-to-side shunting (n = 7), animals experienced a significant, permanent fall in hepatopetal portal blood flow (HABF). In contrast, dogs with side-to-side shunts (n = 7) exhibited a transient, significant increase in HABF 1 hour after surgery. Although the shunt eliminated HPBF, the rise in HABF prevented a significant, immediate fall in THBF. Three weeks after surgery, however, HABF had returned to the baseline range, and THBF was significantly lower than the preshunt value. Dogs with H-graft mesocaval shunts (n = 5) also exhibited a transient, significant rise in HABF 1 hour after surgery. Since HPBF did not fall substantially, THBF at this time was significantly higher than the baseline value. Three weeks after surgery, HABF had fallen to the baseline range, but THBF was not significantly different from the preshunt level. In animals with distal splenorenal shunts (n = 11), there was no significant change in HABF after shunting. Both HPBF and THBF were transiently, significantly reduced immediately after surgery, but three weeks later neither parameter was significantly lower than the preshunt values. There were no significant, persistent changes in the systemic perfusion pressures or flows in the shunted groups. These experiments demonstrate that the reported increase in HABF following portasystemic shunting is dependent on the type of shunt and, if it occurs, is a transient phenomenon. Hence, immediate postoperative changes in hemodynamic variables or hepatic blood flows do not necessarily reflect long-term patterns. In the normal dog, total portasystemic shunting produces a permanent, significant decrease in THBF, whereas selective shunting maintains THBF in the near-normal range.