Experimental evaluation of portal venous pulsatile flow synchronized with heartbeat intervals: effects of vascular clamping on portal hemodynamics.

Abstract

We previously showed that blood flow in the portal vein was pulsatile and influenced by both the inferior vena cava and the arterial system in a complex manner (Nihei et al., 38:141-149, 2011). The objective of the present study is to identify determinants of blood flow and to clarify the source of pulsatile flow in the portal vein. Three-breed terminal crossbreed mini-pigs underwent general anesthesia. Pressure and flow in the portal vein, inferior vena cava, hepatic artery, and mesenteric artery were measured simultaneously. Vascular occluders were placed in the inferior vena cava, hepatic artery, and mesenteric artery to examine the effects of clamping on portal venous flow. Clamping of the mesenteric artery altered pressure and flow waves in the portal vein to waveforms similar to those in the inferior vena cava. Waves resembling those of the inferior vena cava superimposed on portal venous flow appeared later than waves of the inferior vena cava. Clamping of the inferior vena cava promptly altered portal venous pressure and flow. Because clamping of the inferior vena cava led to a sharp rise in portal venous pressure, detailed evaluations were not feasible. Clamping of the hepatic artery had no effect on flow-wave pulsation in the portal vein. In the hepatic circulation, flow-wave pulsation in the portal vein is influenced by flow in the inferior vena cava via the sinusoids and by flow in the mesenteric artery via the capillary vessels of the intestine.