Abstract
Congenital portosystemic shunt, also known as Abernethy malformation, is a rare vascular anomaly in which portal venous blood partially or completely bypasses the liver and enters the systemic circulation. This condition can lead to severe complications such as hepatopulmonary syndrome, hepatic encephalopathy, hypoxemia, and hyperammonemia. This article presents the first clinically confirmed and successfully treated case of Abernethy type II malformation in a child in Kazakhstan, who developed severe hepatopulmonary syndrome. A detailed description is provided of the diagnostic algorithm, angiographic evaluation, the endovascular intervention technique, and the patient’s clinical course over a five-year follow-up period. Shunt closure resulted in marked clinical improvement, including normalization of oxygen saturation (from 60% to 98%), reduction in blood ammonia levels, increased exercise tolerance, and enhanced quality of life.The findings support the effectiveness of an individualized, stepwise approach in the management of type II CPSS. The importance of early recognition of this condition is emphasized, particularly in pediatric patients presenting with unexplained cyanosis, hypoxemia, or signs of hepatic dysfunction. Endovascular techniques, due to their minimally invasive nature and high clinical efficacy, represent an optimal therapeutic strategy in pediatric practice.