Asymptomatic Pulmonary Edema in Children With Secundum Atrial Septal Defect: A Bedside Lung Ultrasound Screening Study.

BACKGROUND: Secundum atrial septal defect (ASD II) is a common congenital heart defect that produces a left-to-right shunt and increases pulmonary blood flow. Whether chronic pulmonary overcirculation raises extravascular pulmonary fluid before overt symptoms appear is uncertain. Lung ultrasound is a rapid, noninvasive, radiation-free bedside method that detects extravascular lung fluid through B-line artifacts and is an established tool for assessing pulmonary congestion. OBJECTIVE: This study aimed to screen for sonographic evidence of pulmonary edema in clinically asymptomatic children with isolated ASD II using bedside lung ultrasound. METHODS: This prospective observational single-center study was conducted from January 2025 to May 2026. Children aged two to eight years with an echocardiographically confirmed ASD II, without chronic lung disease and without another significant shunt lesion or complex congenital anatomy, were screened. Echocardiography was performed per American Society of Echocardiography guidelines, and the pulmonary-to-systemic flow ratio (Qp/Qs) was estimated echocardiographically. Lung ultrasound was performed at the bedside with a portable system (SonoSite; Fujifilm SonoSite Inc., Bothell, WA) using a high-frequency hockey-stick linear probe (HSL25x, 6-13 MHz). A scan was defined as positive when at least three B-lines were present in at least two bilateral lung zones. Descriptive statistics were used. RESULTS: Ten children were included (seven female, three male; mean age, 4.3 years; range, 2-8). Mean ASD diameter was 16.2 mm (range, 9.6-28.0), and the mean Qp/Qs was 2.8 (range, 1.26-4.4). Pro-B-type natriuretic peptide was available in eight of 10 children and was within the normal range in all of them. Lung ultrasound was positive in one of 10 children (10%) and negative in nine (90%). The single positive scan occurred in a child with a normal natriuretic peptide level, no comorbidity, and a moderate defect; the children with the largest defect and the highest shunt ratios all had negative scans. CONCLUSIONS: In this small cohort of asymptomatic children with isolated ASD II, sonographic signs of increased extravascular lung water were uncommon and did not correlate with defect size, shunt magnitude, or natriuretic peptide level. Bedside lung ultrasound was feasible. These findings require confirmation in larger, controlled studies.