Unanticipated Abdominal Compartment Syndrome in an Infant Undergoing Atrioventricular Septal Defect Repair

Atrioventricular septal defect (AVSD) is a common congenital cardiac condition, particularly in patients with trisomy 21, requiring surgical correction in infancy to prevent progressive heart failure and pulmonary hypertension.[1,2] Abdominal compartment syndrome (ACS) is a rare but potentially life-threatening complication, often linked to excessive fluid resuscitation or capillary leak syndrome.[3,4] We present a rare and highly unusual case of ACS developing intraoperatively during cardiopulmonary bypass (CPB) in a 6-month-old undergoing AVSD repair, a complication not previously described during pediatric cardiac surgery.