Pancreatic Siphon: A Major Determinant of Selective Shunts. Is it a Historical Entity now?

Abstract

Surgical management of portal hypertension has changed according to time, evolving from just complete shunts to selective shunts and to liver transplantation. The outcomes also greatly improved owing to better understanding of portal hemodynamics and disease nature. Introduction of selective shunts showed promising results just to be challenged by poor outcome with development of "pancreatic siphon" which then studies in detail. This intra-pancreatic and peri-pancreatic collateral veins which connected portal and splenic veins formed basis of systemic loss of portal flow and thus ending up in failure of selectivity. Pancreatic siphon was found to be associated with increased rates of hepatic encephalopathy post selective shunting along with increased rates of hepatic failure. In addition to this pancreatic siphon led to metabolic sequel like new onset of diabetes, ischemic or compressive pancreatic ductopathy and intrapancreaic cholangiopathy. Although the shunting procedures are not that commonly done, pancreatic siphon has moved out of the limelight. It was just an attempt of recapping the existence of an unfamiliar entity forming delicate balance in the portal circulation. radicals connecting portal and splenic circulations [3]. Furthermore in response to pathology like portal venous thrombosis and splenic venous thrombosis these collaterlas tend to dilate and decompress respective compartments [3]. So development of pancreatic siphon is natural response of persistent elevated pressure in the mesentericoportal circulation over the intra-pancreatic and peri-pancreatic venous channels after splenic venous division and DSRS. Even such intra-pancreatic collaterals are seen in portal venous thrombosis with or without liver cirrhosis, without any clinically significant mass effect [4]. Ligation of coronary vein is a crucial step in creation of DSRS, failure of which can hasten the collateralisation and early formation of pancreatic siphon effect [5]. This intra-pancreatic collateral network along with coronary vein helps in decompressing gastrospenic compartment in inferior mesenteric-renal shunt which is a rare type of selective shunt [2]. The alcoholic patients, cirrhotics and post hepatitis patients were found to be specially prone for the development of pancreatic siphon [6], following selective shunts and porto-splenic thrombosis.