Computational Fluid Dynamics as an Adjunctive Functional Assessment of Airway Narrowing After Pulmonary Artery Banding: A Case Report.

Airway compression is a recognized complication after pulmonary artery banding (PAB) in infants with congenital heart disease; however, conventional imaging primarily provides anatomical information. We report an infant with respiratory instability after PAB who underwent computational fluid dynamics (CFD) as an adjunctive functional assessment. After extubation, recurrent intercostal retractions and oxygen desaturation occurred during crying. Contrast-enhanced CT and bronchoscopy revealed mild-to-moderate tracheobronchial narrowing caused by dilated pulmonary arteries without intrinsic obstruction. A patient-specific CFD model simulated inspiratory airflow at 100 mL/s, approximating crying. Total airway resistance was markedly elevated (15 Pa/mL/s vs. approximately 0.07 Pa/mL/s in healthy infants), with pronounced airflow asymmetry and reduced flow to the right main bronchus, suggesting functional impairment despite relatively preserved airway lumens. These findings were considered complementary to the overall clinical assessment, rather than an independent surgical indication. The patient's symptoms resolved after pulmonary artery plication and ventricular septal defect closure.