Radiological definition of a new model of portal diversion in the rat

Abstract

Diversion of portal blood away from the liver can be accomplished in the rat by two straightforward surgical procedures: subcutaneous transposition of the spleen followed later by portal vein ligation. This experimental model has great potential value in the study of liver cell transplants, porto-systemic shunts and hepatic porto-privation. Contrast medium radiology has been used to clarify and define the model further. Splenography, achieved by direct percutaneous puncture, demonstrated the developing spleno-subcutaneous vessels. Collaterals are seen as early as 3 days and appear extensive by 21 days after transposition. Almost all emanate from the convex outer surface of the spleen and course cranially and caudally in the subcutaneous tissues to drain into the subclavian and iliac veins. The appearance of these collaterals correlates well with survival after portal vein occlusion subsequent to splenic transposition. Direct portography demonstrates that, following portal vein ligation, contrast medium is diverted away from the liver into the splenic veins, through and around the spleen, before draining into the systemic circulation through spleno-subcutaneous collaterals. These radiological studies have demonstrated the changed circulatory pathways of this model of portal diversion and have confirmed that it is the splenic veins and the spleno-subcutaneous collaterals which are fundamental to its successful outcome.

Induction of intestinal ischemia reperfusion injury by portal vein outflow occlusion in rats

“…Clamping of the distal branches of the mesenteric vein and of the intestinal lumen could have resulted in a higher degree of ischemia and injury that was not related to venous congestion alone. Portal vein stenosis has been previously shown to result in even higher mesenteric vein pressures than mesenteric vein clamping itself [15], as porto-systemic shunts do not develop within minutes of acute portal occlusion [16].…”

Partial Splenectomy, Transposition of the Spleen to the Abdominal Wall or Splenohepatoplasty in Portal Hypertensive Rats. Effects on Portal Venous Pressure and Homeostasis - Microscopical Appearance of the Transposed Spleen

“…Concomitantly to the wound healing, venovenous portosystemic shunts (Figs. 2, 5, 6) and lymphatic communications will develop (1,2,3,10,12,13,14,31,33). Table 1 Body weights, relative weights of liver, platelet counts, serum pratein levels, colloid osmotic pressure and ammonium levels (M±MAD).…”

“…Experimentally, the model of portosysternic diversion by subcutaneous transposition of the spleen was used to study portal circulation, collateral capacity after complete ligature of this vein or to evaluate the efficiency of this method for enhancing the survival rate after hepatectomy (3,12,13,18).…”

Dynamic Pressure Measurements in the Evaluation of a Pancreaticolienal Portal Diversion Model in the Rat

“…This has been recently demon strated radiologically in our laboratory. Con trast medium -infused into a mesenteric vein -outlines the dilated portal trunk and splenic veins; it is then seen passing through and around the splenic pulp before draining into the systemic circulation via the profuse splenosubcutaneous collaterals [5].…”

“…If the spleen is scarified at the time of trans position, mature splenosubcutaneous vessels develop [5] and acute portal vein transec tion, a procedure which is normally uni formly fatal, can be performed 2-4 weeks later without significant mortality [6]. It ap pears that following transection a new circu latory pathway is established in which splenic vein flow is reversed, portal blood being diverted across the pancreas and spleen before draining via splenosubcuta neous collaterals into the general circulation [5] (fig. lb).…”