Overview
An intrahepatic arterio-portal shunt is a shunt of blood from the intrahepatic artery to the portal vein, where part of the blood from the intrahepatic artery does not pass through the normal microcirculatory system but circulates directly between the artery and the vein, and includes hepatic arterio-portal vein fistulae.
Pathogenesis
1. Pathogenic factors
Including congenital diseases and secondary diseases. Congenital diseases include congenital arteriovenous malformation, infantile hepatic hemangioendothelioma, hereditary hemorrhagic capillary dilatation, Ehlers-Donald syndrome, and congenital hepatic amyloidosis. Secondary diseases commonly include primary hepatocellular carcinoma, followed by cirrhosis, metastatic carcinoma of the liver, gastrointestinal hemorrhage, extrahepatic portal trunk and/or splenic vein obstructive diseases (e.g. acute pancreatitis, pancreatic cancer, etc.).
2. Pathogenic conditions
Elevated pressure in the hepatic sinusoids, direct communication between the walls of the hepatic artery and portal vein or formation of traffic in the neovascular network, hemodynamic changes.
3.Triggering factors
For example, overeating is prone to acute pancreatitis, inflammatory diseases, ulcerative diseases or digestive tract tumors are prone to cause gastrointestinal bleeding and so on.
Symptoms
A small amount of shunt has no effect on portal vein blood flow, so there is no characteristic clinical manifestation. Those with large shunt volume have the manifestations of portal hypertension and portal-body shunt, i.e. the clinical manifestations of related diseases, such as splenomegaly, hypersplenism, ascites, the establishment and opening of portal-body collateral circulation (e.g. hemorrhage, abdominal wall and periumbilical varicose veins, etc.) as the typical manifestations of portal hypertension.
Examination
CT, dynamic enhancement imaging of magnetic resonance imaging and hepatic artery stage of angiography can show simultaneous visualization of portal vein branches and hepatic artery branches, early visualization of portal vein trunk before splenic vein and superior mesenteric vein, and transient hepatic parenchymal enhancement.
Diagnosis
The etiology of this disease is complex and the clinical manifestations are not obvious, so the diagnosis is mainly based on imaging data. Hepatic arteriography shows early visualization of the portal vein; CT examination shows early visualization of portal vein branches. Doppler ultrasonography can assist in the diagnosis by detecting regurgitation of more than three levels of branches.
Differential diagnosis
Hepatic hemangioma with intrahepatic artery-portal vein shunt has similarity with hepatocellular carcinoma in imaging manifestations, and liver biopsy is needed to differentiate when necessary.
Treatment
For small amount of shunt, no treatment is needed. For large amount of shunt, hepatic artery embolization or transjugular intrahepatic porto-caval shunt can be performed to relieve symptoms. For those with gastrointestinal hemorrhage and inflammatory etiology, medication is needed to control the condition. Tumor patients should undergo timely surgical treatment, and hepatic artery chemoembolization is feasible for those without surgical indications. Liver transplantation can be considered if drug treatment, surgery and chemotherapy are ineffective.
Prognosis
The prognosis of intrahepatic artery-portal vein shunt is related to the primary disease and the amount of shunt, a small amount of shunt without other accompanying diseases may have no effect in the whole life, and the prognosis of tumor-induced intrahepatic artery-portal vein shunt is related to the benignity and malignant nature of the tumor, typology, staging and so on, so it can’t be generalized.