A new direct portosystemic collateral in canine portal hypertension

Two different models of extrahepatic portal obstruction were prepared in dogs to examine the development of portosystemic collateral pathways. The collateral pathways that developed were of two main types, portosplenic communications with the azygos system and a direct communication between the portal vein complex and the intrathoracic part of the inferior vena cava (IVC). This direct communication between the portal venous system and the IVC was unknown to us prior to these studies. The channel we describe has a potential for directly inducing pulmonary embolism, a possibility not seriously considered so far.