Case Report: Higher modelled pulmonary wall shear stress in an adult with Celoria-Patton type B aortic interruption, ventricular septal defect, and patent ductus arteriosus.

Background: Interrupted aortic arch (IAA) is a rare congenital cardiac anomaly, almost invariably lethal in the neonatal period without surgical intervention, with adult survival exceedingly rare. The hemodynamic consequences of uncorrected Celoria-Patton type B IAA with a ventricular septal defect (VSD) and a patent ductus arteriosus (PDA) have not been previously characterized by 4D cardiac computed tomography (4D-CCT)-based computational fluid dynamics (CFD). Case presentation: An 18-year-old woman with known congenital heart disease since childhood but without complete anatomic characterization presented with exertional dyspnea (NYHA class II), a grade 6/6 holosystolic murmur, and a 22 mmHg arm-leg blood pressure gradient. Echocardiography identified a large perimembranous VSD (3.33 cm) with bidirectional flow, a 0.60 cm ductus arteriosus, severe tricuspid regurgitation (PGmax 203 mmHg), and an estimated pulmonary artery systolic pressure of 168 mmHg. 4D-CCT confirmed Celoria-Patton type B IAA with the descending thoracic aorta arising as a ductal continuation from the right pulmonary artery and supplying the left subclavian artery distally. Right heart catheterization documented severe predominantly pre-capillary pulmonary hypertension (mPAP 82 mmHg; PAWP 9 mmHg; PVRi 9.6 Wood units·m Conclusion: In adults with unrepaired type B IAA, 4D-CCT-based CFD characterizes bidirectional shunting and provides hypothesis-generating biomechanical information concordant with invasive hemodynamics; it may be useful for longitudinal surveillance of pulmonary artery geometry.