What are the options for closing intrahepatic shunts?
There are three different techniques available
- Direct Shunt embolisation (Novel technique used at SCVS)
Does closure of intrahepatic shunts always work?
The two main potential complications following closure of intrahepatic shunts are:
- Development of portal hypertension
- Formation of collateral secondary shunt vessels
Portal hypertension commonly develops following shunt closure as a consequence of poorly developed vasculature in the liver. Following shunt closure, the large blood volume normally draining from the gastrointestinal tract into the
systemic circulation is partially occluded. In order for shunt closure to be successful gradual closure of the shunt, which
allows hepatic vessels to re-develop, is key. Gradual closure using surgical ligation or stent & coil techniques can only achieved with repeated procedures. The novel Direct Shunt embolisation achieves gradual shunt closure after only one intervention in most patients, using a unique and complex heparinisation protocol.
Formation of collateral secondary shunt vessels
Hepatic veins have pre-connections between each other. These connections are usually non-patent and don't carry any blood flow in normal circumstances. However, with increased hepatic venous pressure these connections become patent, resulting in the formation of secondary
Hepatic vein pressure increases if the hepatic vein instead of the shunt vessel itself is closed as this is often the case with surgical shunt ligation and the stent&coil technique. Direct Shunt embolisation does not carry this risk.
Formation of collateral shunt vessels
The intrahepatic shunt (black part of the vessel) connects the portal vein (purple vessel) with the hepatic vein (blue) and caudal vena cava. 'Toxic' blood reaches the systemic circulation via the shunt vessel.
The portal vein branches into the liver, but these branch vessesls are usually underdeveloped and only very few are present.
Several hepatic veins (small blue vessels) exist and drain the liver pranchyma.
There are preformed connections between all the hepatic veins (dotted lines). These remain closed and do not carry any blood flow as long as the pressure within the liver veins remains low
Ligation of the hepatic vein will dramatically increase the pressure within the hepatic veins
Pre-formed connections between the hepatic veins open and a new shunt vessel develops