Portal circulation and portal hypertension.

Abstract

During the last 25 years, there have been important developments in visualising the portal vein, in examining its contents, and in measuring the pressure of blood flowing within it. Radiologists have set the scene and now is the time of the scanner. These technical advances have been applied to the diagnosis and treatment of patients with portal hypertension, and many ingenious surgical techniques have been proposed. The problem of successful treatment of the patient with bleeding oesophageal varices and cirrhosis of the liver, however, has not yet been solved. This report discusses the portal vein in terms of pressure, flow, and regeneration factors. Portal hypertension is classified and methods of relief are discussed. Methods of visualising the portal vein RADIOLOGICAL TECHNIQUES Peroperative injection of contrast material directly into portal vein or one of its tributaries This method has the obvious disadvantage of necessitating surgery. Filling of the portal system can be so great that interpretation of anatomy is difficult. Splenic venography This is simple to perform. The portal system and collaterals are seen particularly clearly and the portal pressure can be measured at the same time through the splenic needle. The small risk of haemorrhage from the splenic puncture is a disadvantage. Abnormal blood clotting or deep jaundice are contraindications. .Selective visceral angiography The coeliac axis is catheterised via the femoral artery with a pre-formed opaque catheter and the injection of a bolus of radio-opaque contrast material'. The portion of contrast material that flows into the splenic artery returns through the splenic and portal veins and produces a splenic and portal venogram of variable quality. Similarly, a bolus of contrast material introduced into the superior mesenteric artery returns through the superior mesenteric and portal vein, which can be seen in radiographs exposed at the appropriate intervals. The portal vascular bed is not seen so clearly as with splenic venography. Because splenic venous blood may be diverted into large gastro-oesophageal collaterals a splenic venogram may occasionally show a non-filled portal vein, even though the vein is patent. In such cases, a mesen-70

COMPARISON OF PER‐RECTAL PORTAL SCINTIGRAPHY USING 99mTECHNETIUM PERTECHNETATE TO MESENTERIC INJECTION OF RADIOACTIVE MICROSPHERES FOR QUANTIFICATION OF PORTOSYSTEMIC SHUNTS IN AN EXPERIMENTAL DOG MODEL

“…Per-rectal administration of technetium-99m pertechne- [10][11][12][13][14][15] seconds following deposition of 99mT~04-in the colon.27 Normally 99mT~04-reaches the liver 8-16 seconds before it enters the heart (Fig. 1).…”

A Bypassing Technique for the Remedy of Portal Hypertension through Extra Hepatic Portal Vein Obstruction by CFD Analysis

“…As seen in previous reports, the thrombosis is often limited to the portal trunk and does not extend into the intrahepatic branches [15][16]. Here we consider Extra Hepatic Portal Vein Obstruction (EHPVO) by forming partial block in the main portal vein (without involving intrahepatic obstruction).…”

Hemodynamic Changes in Patients with Portal Venous Obstruction

“…This normal hepatic venous pressure gradient suggests normal liver architecture and no liver cell lesions. In patients with portal venous obstruction, the association of an elevated splenic venous pressure with a normal hepatic venous pressure gradient has confirmed that portal hypertension is of the so-called infrahepatic type (10,11); this type of portal hypertension differs from intrahepatic portal hypertension in which splenic venous pressure and hepatic venous pressure gradient are elevated. However, a slight increase in the hepatic venous pressure gradient has been reported in patients with normal liver architecture but with either intrasinusoidal fibrosis or major liver cell necrosis (12,13).…”

“…However, a slight increase in the hepatic venous pressure gradient has been reported in patients with normal liver architecture but with either intrasinusoidal fibrosis or major liver cell necrosis (12,13). The elevated hepatic venous pressure gradient is a well-known consequence of liver architecture distortion and is observed in patients with cirrhosis (10,14).…”