Association of Bulboventricular Foramen Size and Need for Early Intervention in Infants with Tricuspid Atresia or Double-Inlet Left Ventricle with Normally Related Great Arteries.

Background: The association of bulboventricular foramen (BVF) size and systemic outflow adequacy has been studied in patients with tricuspid atresia (TA) or double-inlet left ventricle (DILV) with transposed great arteries. The aim of this study was to determine the relationship between initial BVF size and risk for progressive pulmonary outflow obstruction requiring intervention to increase pulmonary blood flow in patients with TA or DILV with normally related great arteries.

Methods: Patients with TA or DILV with normally related great arteries were identified by retrospective chart review at a single center from 2005 to 2021. Patients were stratified by indexed BVF area (iBVFA) to determine the relationship of iBVFA size and the need for intervention before the Glenn operation to establish supplemental pulmonary blood flow with either a Blalock-Taussig-Thomas shunt (BTTS) or patent ductus arteriosus (PDA) stent. Patients were followed through the time of their Glenn operations. Logistic regression analysis was performed to determine optimal iBVFA cut points.

Results: Thirty-seven patients with TA or DILV with normally related great arteries were included. Sixteen had iBVFA < 1 cm/m, with all 16 (100%) requiring either a BTTS or PDA stent to increase pulmonary blood flow before the Glenn operation. Seventeen had iBVFAs of 1 to 2 cm/m, with 10 (59%) requiring either a BTTS or PDA stent. Nine of those 10 demonstrated flow acceleration across the BVF and/or pulmonary outflow tract. Four had iBVFA > 2 cm/m, with only one patient (25%) requiring a BTTS. Among our cohort, an iBVFA of <1.8 cm/m provided sensitivity of 96% with good positive and negative predictive values (81% and 80%, respectively) for requiring intervention with a BTTS or PDA stent before the Glenn operation.

Conclusions: An iBVFA of ≤1.8 cm/m on initial postnatal echocardiography is associated with the development of subpulmonary obstruction requiring intervention with a BTTS or PDA stent before the Glenn operation, with the highest risk noted in those with iBVFA of ≤1 cm/m. Factors such as BVF flow acceleration or pulmonary outflow tract narrowing should also be considered in the decision to augment pulmonary blood flow.