Hemodynamic and morphologic evaluation of the spleen after splenic vein ligation in the dog.

The splenic vein was ligated in ten dogs in order to evaluate the time course of changes in splenic size and to relate them to splenic arterial flow, splenic pressure and development of venous collaterals. Following ligation of the splenic vein, splenic size and venous pressure immediately rose in all dogs. Arterial flow to the spleen simultaneously fell in roughly inverse proportion to the elevation of venous pressure. During the following weeks, the splenic parenchymal pressure decreased to basline levels in all but one dog, as collateral veins developed through the gastric venous network to the portal vein. Splenic size gradually decreased toward normal in eight of the ten dogs. At the time of sacrifice, 8-16 weeks after splenic vein ligation, pathologic examination demonstrated fibrosis from healed infarction. Recent hemorrhage, indicating persistence of the congestive process, we also present, although difficult to explain in view of normal splenic parenchymal pressure.