Fontan Outcomes in Oligemia vs Plethora in Univentricular CHD

This prospective cohort study evaluates differences in clinical outcomes between pulmonary oligemia and pulmonary plethora in patients with cyanotic congenital heart disease and univentricular heart physiology undergoing staged palliation culminating in the Fontan procedure.Fifty-two patients will be classified into two groups based on pulmonary blood flow characteristics and followed for approximately 1.5 years after the Fontan procedure. Outcomes include mortality, morbidity, pulmonary hemodynamics, functional capacity, neurocognitive status, and quality of life.

Univentricular heart physiology represents a complex form of congenital heart disease requiring staged surgical palliation. The Fontan procedure has improved survival; however, outcomes remain variable and are influenced by pulmonary vascular conditions. Pulmonary blood flow abnormalities-oligemia (reduced flow) and plethora (increased flow)-may affect lung development from fetal life. Oligemia has been associated with pulmonary hypoplasia, impaired alveolar formation, and increased pulmonary vascular resistance, which may adversely affect Fontan circulation. This prospective cohort study aims to compare outcomes between patients with oligemia and those with plethora. Participants will undergo standard clinical care, including staged procedures (Bidirectional Glenn and Fontan), and comprehensive assessments (clinical, laboratory, imaging, and hemodynamic). Follow-up will be conducted for approximately 1.5 years post-Fontan. The study will evaluate mortality, morbidity, pulmonary hemodynamics, biomarkers (NT-proBNP, ET-1, Activin-A), exercise capacity, neurocognitive outcomes, and quality of life. Findings are expected to improve risk stratification and management strategies in univentricular CHD.

Inclusion Criteria: * Diagnosed cyanotic CHD * Univentricular heart physiology * Planned staged palliation including Fontan procedure * Informed consent obtained (patient or guardian) Exclusion Criteria: * Refusal to participate * Incomplete clinical data * Inability to complete follow-up