Background <p>A univentricular heart is a rare congenital heart defect usually diagnosed prenatelly or at the time of birth. Early intervention and continuous monitoring are crucial, especially when the condition is diagnosed later in life.</p> Case summary <p>A man in his 20 s with a known univentricular heart defect presented to a hospital seeking asylum. He showed signs of cyanosis, affecting his lips, nose, and hands. An echocardiogram revealed functional single-ventricle physiology due to a hypoplastic non-functional right ventricle and malposition of the great arteries. Given his complex condition, he was scheduled for a central transplantation evaluation. However, three days after admission, he developed a severe respiratory infection, significantly complicating his treatment and requiring urgent intervention.</p> Discussion <p>This case underscores the rarity of complex congenital heart defects in adults, such as functional single-ventricle physiology with malposition of the great arteries. Double inlet left ventricle occurs in approximately 0.05–0.1 per 1,000 live births (J Am Coll Cardiol. 2004;43(1):113–9). while transposition of the great arteries affects 1 in 3,500-5,000 live births (Orphanet J Rare Dis. 2008;3:27). when occuring in isolation. The coexistence of these anomalies represents an exceptionally rare and complex subset of congenital heart disease.</p> <p>Although many children with these defects undergo early interventions, such as the Fontan procedure, some cases are not identified or addressed until adulthood. As these patients age, the challenges of managing congenital heart defects increase, highlighting the need for a more refined, multi-disciplinary approach to care in adult congenital heart disease.</p>