Collateral Pathways in Portal Hypertension

Abstract

Presence of portosystemic collateral veins (PSCV) is common in portal hypertension due to cirrhosis. Physiologically, normal portosystemic anastomoses exist which exhibit hepatofugal flow. With the development of portal hypertension, transmission of backpressure leads to increased flow in these patent normal portosystemic anastomoses. In extrahepatic portal vein obstruction collateral circulation develops in a hepatopetal direction and portoportal pathways are frequently found. The objective of this review is to illustrate the various PSCV and portoportal collateral vein pathways pertinent to portal hypertension in liver cirrhosis and EHPVO. ( J CLIN EXP HEPATOL 2012;2:338-352) A lmost any vein in the abdomen may serve as a potential collateral channel to the systemic circulation. Presence of abnormal collateral vessels appears to be one of the most sensitive (70-83%) and specific sonographic signs for the diagnosis of portal hypertension. 1 When blood flow through a vessel or a vascular bed is obstructed due to occlusion, as in EHPVO, or distortion, as in liver cirrhosis, collateral pathways open up as blood bypasses the occlusion or obstruction, always flowing down a pressure gradient from a high pressure to a low-pressure vessel or bed. The formation of portosystemic pathways occurs due to reopening of collapsed embryonic channels or reversal of the flow within existing adult veins. 2,3 The number of collateral channels depends on the severity of portal hypertension i.e. the differential gradient driving the flow between the portal and the systemic circulations and the duration of portal hypertension. The more severe and more prolonged the portal hypertension, the higher are the number of portosystemic pathways. However, this traditional hypothesis has been challenged and it has been suggested that the formation of portosystemic collateral circulation may be due in part to angiogenesis driven by vascular endothelial growth factor. 4,5 Almost 50 years have passed since the first detailed description of portosystemic collateral veins (PSCV) in portal hypertension appeared. 6 Precise mapping of PSCV is essential to therapeutic decisions and multidetector computerized tomography (MDCT) is sometimes used for cartography of PSCV. 7 EUS is increasingly being used for evaluation of PSCV and additionally provides an option for performing therapeutic interventions. 8 In addition to PSCV, PPCV pathways are frequently found in extrahepatic portal vein obstruction (EHPVO). The objective of this review is to illustrate the various PSCV and PPCV pathways pertinent to portal hypertension in liver cirrhosis and EHPVO. NORMAL PORTOSYSTEMIC ANASTOMOSESThe left gastric vein (LGV) anastomoses with the esophageal veins, which in turn drain into the azygos vein (AV). The superior rectal vein (SRV) anastomoses with the middle and inferior rectal veins (IRV), which are, respectively, tributaries of the internal iliac and the pudendal veins. The paraumbilical vein (PUV) anastomoses with subcutaneous veins in the anterior abdominal...

Successful Treatment of Bleeding Rectal Varices with Balloon-Occluded Retrograde Transvenous Obliteration in a Patient with a History of Sigmoidectomy

“…Rectal varices represent portal systemic collaterals that manifest as discrete dilated submucosal veins and constitute a pathway for portal venous flow between the superior rectal veins of the inferior mesenteric system and the middle and inferior rectal veins of the iliac system [1].…”

“…The development of portosystemic collateral vessels is common in portal hypertension due to liver cirrhosis [1]. Rectal varices are a type of ectopic varices that occur outside of the gastroesophageal region.…”

Imaging and radiological interventions in extra-hepatic portal vein obstruction

“…Additionally, there is opening up of multiple portosystemic collaterals (mainly left gastric and perisplenic) as a compensation to distribute the high splanchnic bed pressure. Sometimes, the accessory portal veins of Sappey which enter the liver capsule via falciform ligament, triangular ligament, gastrohepatic omentum, bare area of liver or ligamentum venosum supply portal blood to the liver by forming transhepatic portosystemic shunts (PSS) [3] . The cavernous transformation of portal vein and resultant extra and intrahepatic biliary ductal and gall bladder complications has been termed portal cavernoma cholangiopathy (PCC) also called portal biliopathy.…”

Utility of cone-beam computed tomography in the assessment of the porto-spleno-mesenteric venous system

“…As the resistance increases, there is redirection of blood flow. Collateralization aims to return blood to the liver via porto-portal collaterals or into systemic circulation via porto-systemic collaterals or both (15). There are a few common and several uncommon sites for these collaterals (16).…”