Experimental evaluation of portal venous pulsatile flow synchronized with heartbeat intervals

The aim of this study was to analyze pulsatile flow in the portal vein, to clarify the origin of pulsatile flow, and to acquire new knowledge about the hepatic circulation.

Mini-pigs underwent general anesthesia. Pressure and flow in the portal vein, inferior vena cava, hepatic artery, and mesenteric artery were measured simultaneously. We (1) studied the relationship between changes in pressure and changes in flow and (2) measured heartbeat intervals and the onset times of pressure and flow waves.

In the inferior vena cava, pressure and flow showed mirror-image changes. In the hepatic artery and the mesenteric artery, pressure and flow increased simultaneously. In the inferior vena cava, the longer the heartbeat interval, the more delayed were the onset times of pressure and flow waves. The onset time of pressure and flow waves in the hepatic artery and the mesenteric artery was only minimally affected by changes in heartbeat interval. The relationship between pressure and flow in the portal vein was closer to that in the hepatic artery and the mesenteric artery. However, the onset times of pressure and flow waves in the portal vein showed two different patterns: some showed a pattern similar to that of the inferior vena cava, whereas others showed a pattern similar to that of the hepatic artery and the mesenteric artery.

Blood flow in the portal vein is pulsatile and influenced by both the inferior vena cava and the arterial system in a complex manner.