Definition: Arteriovenous malformations are congenital anomalies of the hepatic vessels characterized by an abnormal formation of the hepatic blood vessels. Due to this abnormal formation, an arteriovenous shunt is created. There is no association with the hepatic neoplasias.
Ultrasound findings: The ultrasound findings include enlarged vessels located in one lobe of the liver. The prenatal diagnosis is difficult.
Differential diagnosis: Hemangioma. MRI imaging might be use for distinguish an arteriovenous malformation from a hemangioma.
Diagnosis: A hepatic arteriovenous malformation manifests clinically in neonates with anemia, hepatomegaly and portal hypertension. Sometimes it can also manifest in late childhood with hepatic ischemia and portal hypertension
Definition: Fetal hepatic arteriovenous fistulas are rare and associated with a high mortality rate. They consist in a communication between the hepatic artery and the portal venous system. Congenital arterioportal fistulas are a rare cause of portal hypertension. They can be classified in:
Ultrasound findings: The most common sign is a dilatation of the hepatic artery and the segment of the portal vein where the fistula is located. Doppler is the most useful tool for making the diagnosis.
Diagnosis: Most of patients are asymptomatic within the first year of life. The symptoms as portal hypertension, splenomegaly, hypersplenism and ascites, can appear only after the first year of life. So, it is difficult to determine if the fistula is congenital or acquired.
Associated anomalies: Hereditary hemorrhagic telangiectasia, Ehlers-Danlos syndrome, and biliary atresia.
Prognosis: Congenital hepatic arterioportal fistula in infants with biliary atresia is difficult to resolve because these infants are abnormally dependent on arterial inflow, and ligation or embolization of the hepatic artery could lead to fatal hepatic necrosis.
Infradiaphragmatic Anomalous Pulmonary venous connections
Definition: Anomalous Pulmonary venous connections refer to abnormal connection between the pulmonary veins and the atria. Instead of connecting to the left atrium, the anomalous veins connect to the right atrium or one of the systemic veins. It can be classified accordingly their location and their type:
In total (or complete) anomalous pulmonary venous connection, 20 to 25% are infra-diaphragmatic, connection with the portal-hepatic veins and are obstructed. In 1/3 of cases, the connection is to the innominate vein via a vertical vein.
Associated anomalies: Associated anomalies can be found in one third of the cases and includes: atrial septal defect, hypoplastic left ventricle, heterotaxy syndromes, truncus arteriosus, coarctations and transposition of the great arteries.
Ultrasound findings: A very characteristic sign is the absence of confluence of the pulmonary veins with the left atrium. The right heart may be enlarged from the right sided increased in flow. The left heart may appear comparatively small. Finally in the infradiaphragmatic form, the pulmonary vein drain into an anomalous "verticalâ€ vein that extends caudally to connect in the liver to the hepatic circulation Doppler helps determine the vascular nature of the tubular structure. It also helps identify the level of obstruction.
Prognosis: The prognosis depends on: the number of veins affected the degree of obstruction and the presence of associated anomalies. The total anomalous pulmonary veins return consists of progressive clinical deterioration.
1. Gallego C, Velasco M, Marcuello P, Tejedor D, De Campo L, Friera A. Congenital and Acquired Anomalies of the Portal Venous System. RadioGraphics 2002; 22:141—159
2. Sozos J. Fasouliotis, MD, Reuven Achiron, Zvi Kivilevitch, MD, Simcha Yagel, MD. The Human Fetal Venous System Normal Embryologic, Anatomic, and Physiologic Characteristics and Developmental Abnormalities J Ultrasound Med 2002;21:1145—1158
3. Gallego C, Miralles M, Carlos Marin C, Muyor P, Gonzalez G, GarcÃ½a-Hidalgo E. Congenital Hepatic Shunts. RadioGraphics 2004; 24:755—772