CPSS are rare intrahepatic or extrahepatic vascular malformations redirecting blood flow from the portal circulation to the systemic circulation, bypassing the liver.  Extrahepatic portosystemic shunts (EPSS) or “Abernethy malformations” have aberrant connections between the porto-mesenteric vasculature before PV branching and a systemic vein.  Type 1 EPSS have no portal venous perfusion of the liver while Type 2 EPSS have partial portal perfusion of the liver. Intrahepatic shunts, are classified based on the abnormal connections between intrahepatic branches of the portal vein and the hepatic veins or IVC. [5, 6] There are four subtypes which include: a single large vessel connecting the right portal vein to the IVC (type 1), localized peripheral connections between peripheral PV branches and the hepatic veins in a single hepatic segment (type 2), an aneurysmal connection between a peripheral PV and hepatic vein (type 3), and localized peripheral connections between peripheral PV branches and the hepatic veins in bilateral hepatic lobes (type 4). [5, 7] Our patient was classified as a type 1, intrahepatic CPSS.
Doppler ultrasound is the main mode of diagnosis of CPSS.  Pre-procedural CT angiography and magnetic resonance angiography are often used to further evaluate complex anatomy. Shunt type, location, degree of function, patient age, severity of symptoms, and complication risks are several considerations when planning treatment.  To date, no standard treatment options exist. Given the variability of treatment options, this case study seeks to describe when endovascular approach with an Amplatzer PFO OD is appropriate and how it can successfully be utilized to treat a large type 1 intrahepatic CPSS.
Asymptomatic patients diagnosed with an incidental finding of intrahepatic shunt prenatally or in early infancy should be monitored for a year before definitive intervention, as many intrahepatic CPPS involute by this time.  Symptomatic patients, such as our patient, require immediate treatment to avoid complications associated with encephalopathy and liver dysfunction. [8, 10] Shunt type also determines treatment approach. Many intrahepatic CPSS can be treated with endovascular occlusion or surgical ligation given the presence of other hepatic PV perfusion. For patients with a type 1 EPSS, liver transplantation is required for definitive treatment, while for type 2 EPSS, embolization remains a non-invasive treatment option. 
Careful evaluation of the shunt anatomy helps to determine the appropriate embolic agent for treatment. Considering our patient’s large diameter shunt and high flow, endovascular coils and detachable balloons were considered high risk for migration. Although vascular plugs have frequently been used for treatment of CPSS, few case reports describe the use of the Amplatzer PFO OD. [3, 11, 12] Due to near parallel anatomical alignment between the right PV and IVC and as there was a circumferential hepatic parenchymal flap similar to a PFO, an Amplatzer PFO OD was determined to be a reasonable treatment option. The device’s double disc design enabled placement of one disk in the right PV and the second in the IVC as it flanked the flap. Careful deployment of the device between the two vessels was ensured to avoid fatal outcomes by occlusion of either the right PV or IVC. This device was also chosen in part due to its ease of relocation and retrievability in case of improper positioning. Suboptimal anatomy including an end-to-side shunt or diminutive IVC and portal venous branches would preclude the use of an Amplatzer PFO OD.
Traditionally, surgical ligation has been the main therapeutic treatment for shunts with high flow rates; however, when possible, percutaneous approaches can offer a less invasive and rapid correction of symptoms.  An Amplatzer PFO OD should be considered in endovascular treatment of a large CPPS when the anatomy is amenable.