Low descending aorta flow is associated with adverse feeding outcomes in neonates with small left-sided structures

Feeding intolerance and necrotizing enterocolitis (NEC) cause significant morbidity in neonates with duct-dependent systemic circulations. Whether these complications are associated with low blood flow to the bowel is unproven. The aim of this study was to determine whether low descending aortic (DAO) flow is associated with adverse feeding outcomes in neonates with small left-sided structures, including borderline left ventricle and hypoplastic left heart syndrome (HLHS). The cardiac magnetic resonance (CMR) imaging studies and abdominal Doppler ultrasound profiles prior to any cardiac interventions in neonates with small left-sided structures were analyzed. Descending aortic flows, indexed to body surface area, were collected. Medical charts were reviewed for a composite outcome of feeding intolerance and/or NEC. Among the 51 enrolled study patients (mean age 4.6, SD 4.5 days), 13 experienced the composite outcome (feeding intolerance in 13, NEC in 2). The mean DAO flow in patients who experienced the composite outcome was 0.89 L/min/m² (SD 0.33 L/min/m²), compared to 1.23 L/min/m² (SD 0.41 L/min/m²) in those that did not (p = 0.007). A DAO flow of 0.91 L/min/m² identified patients who experienced feeding intolerance or NEC with a sensitivity of 61% and a specificity of 76%. Doppler ultrasound metrics of DAO flow did not correlate with DAO flow or predict adverse feeding outcomes. Low DAO flow is associated with adverse outcomes, including feeding intolerance and NEC, in neonates with small left-sided structures. Heightened clinical vigilance towards feeding complications in patients with low DAO flow is recommended.