Effective perioperative management of Abernethy Malformation for complex congenital cardiac surgery utilizing zero-balance ultrafiltration

Abernethy malformation is a rare congenital vascular anomaly in which portal venous blood bypasses the liver and drains directly into the systemic circulation. As a result, splanchnic venous blood is not processed by the liver. Clinical manifestations include hyperammonemia causing hepatic encephalopathy, pulmonary arteriovenous malformations, primary pulmonary artery hypertension, and hepatic neoplasms. Herein, we describe the case of a three-year-old male with heterotaxy syndrome and complex congenital heart disease presenting for biventricular repair on cardiopulmonary bypass. He also had Abernethy malformation and a history of hepatic encephalopathy managed with intense medical therapy. Existing literature offers limited guidance on managing Abernethy malformation or hyperammonemia during cardiopulmonary bypass. We were concerned that the perioperative phase of surgery could acutely raise the ammonia to dangerous levels through blood transfusions and hemolysis due to prolonged time on the heart-lung machine and the excessive use of cardiotomy suction and vents using roller pumps. Therefore, a multidisciplinary team developed a comprehensive perioperative plan. This report describes careful monitoring and management across all perioperative phases, with an emphasis on cardiopulmonary bypass ammonia management through zero balanced ultrafiltration (Z-BUF). Together, these efforts contributed to a favorable postoperative outcome.