Univentricular heart

Univentricular heart (also known as single ventricle heart, single ventricle physiology, or cor triloculare biatriatum) is a rare congenital heart defect in which one of the two ventricles of the heart is severely underdeveloped or absent, leaving only one functional pumping chamber. This condition encompasses a spectrum of cardiac malformations including double inlet left ventricle (DILV), double inlet right ventricle, tricuspid atresia with a large ventricular septal defect, and hypoplastic left heart syndrome variants where only one ventricle is capable of supporting systemic circulation. The heart is unable to effectively separate oxygen-rich blood from oxygen-poor blood, leading to mixing of the two circulations. Clinical features typically present at birth or shortly thereafter and include cyanosis (bluish discoloration of the skin due to low oxygen levels), tachypnea (rapid breathing), poor feeding, failure to thrive, and signs of congestive heart failure. Without treatment, the condition is life-threatening in the neonatal period. The severity of symptoms depends on the specific anatomy, the degree of obstruction to pulmonary or systemic blood flow, and the presence of associated cardiac anomalies such as transposition of the great arteries, pulmonary stenosis, or coarctation of the aorta. Treatment involves a staged surgical approach aimed at eventually establishing a Fontan circulation, in which venous blood flows passively to the lungs without a pumping ventricle. This typically involves three operations: the Norwood procedure or pulmonary artery banding in the neonatal period, the bidirectional Glenn or hemi-Fontan procedure at approximately 4–6 months of age, and the Fontan completion at 2–4 years of age. While these palliative surgeries have significantly improved survival, patients require lifelong cardiac follow-up and may face long-term complications including arrhythmias, protein-losing enteropathy, liver fibrosis, exercise intolerance, and eventual heart failure. Heart transplantation may be considered in cases of failing Fontan physiology.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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