Gritti MN, Farid P, Hassan A, Marshall AC. Pediatr Cardiol. 2024 Feb 10. doi: 10.1007/s00246-024-03408-w. Online ahead of print. PMID: 38341390
Take Home Points:
- Residual MPA/branch PA stenosis following the arterial switch operation can result in significant right ventricular hypertension.
- Branch PA angioplasty and branch PA stenting can improve RV hypertension, decrease gradients across the branch PAs, and improve the caliber of the vessel without major adverse events.
- More concrete indications for intervention and long term follow up, especially of stented branch PAs following ASO is needed to help guide optimal therapy.

Commentary from Dr. Ryan Romans (Kansas City, MO), section editor of Congenital Heart Disease Interventions Journal Watch:
Dextro-transposition of the great arteries (d-TGA) is repaired in the neonatal period via the arterial switch operation (ASO) +/- closure of a ventricular septal defect if present. Pulmonary artery translocation with the LeCompte maneuver can results in the branch pulmonary arteries (PAs) both sitting on top of the ascending aorta. Branch PA stenosis is relatively common following this (up to 28% in previous studies) secondary to multiple factors. Additionally, pulmonary artery stenosis at the anastomotic site can also occur, though seem to be decreasing in frequency with improvement in surgical techniques. This, along with branch PA stenosis, can lead to RV hypertension. This study sought to describe the outcomes of transcatheter interventions in this patient population.
A retrospective review of all patients who underwent both an ASO and cardiac catheterization (excluding balloon atrial septostomy) was performed at a single center from 1/2004-12/2020. Patients were excluded if they did not have a right heart catheterization (RHC) performed. A total of 544 patients had an ASO during this time. 110 patients had a cardiac catheterization performed, with 58 patients meeting inclusion criteria. 9 patients underwent a diagnostic RHC only. 49 patients underwent 76 right sided interventional cardiac catheterizations at a median age of 3 ± 3.9 years. Many patients had a cardiac catheterization performed for RV hypertension (42%), branch PA pressure gradient (29%), and significant branch PA size discrepancy (19%). The RV to systemic pressure ratio was higher in the interventional group vs the diagnostic group (0.68±0.21 vs 0.52±0.16, p<0.02). In the intervention group, 33% of patients had a significant RPA gradient and 33% LPA. 17% had a significant size discrepancy. In the 76 interventional catheterizations, balloon angioplasty of the RPA was performed 27, LPA in 42, and MPA in 10. Reduction in the RV hypertension was accomplished with angioplasty of the RPA (0.69±0.17 to 0.54±0.15, p<0.001) and LPA (0.66±0.17 to 0.54±0.17, p<0.001). The RPA gradient was reduced from a mean of 21.4 mmHg to 10.5 mmHg and LPA gradient from 22.8 mmHg to 13.3 mmHg. The size of both branch PAs increased following angioplasty as well (RPA 4.6 to 5.2 mm, LPA 4.4 to 6.8 mm). 15 patients had a stent placed in their RPA and 16 in their LPA with significant reduction in the RV pressure and gradients with near doubling in vessel caliber. 5 patients had stents placed in both branch PAs. There were no complications in the diagnostic RHC cohort and 9 (12%) in the interventional cohort. None of these complications were considered high severity.
This study showed that branch PA interventions in young children following ASO can result in a significant decrease in RV hypertension with an acceptable risk profile. Unfortunately, this study was not able to clearly delineate indications for intervention as determined by noninvasive imaging. I expect there is still significant practice variation across centers given this. Long term follow-up of this population is needed, especially following branch PA stenting, given the known risk of late aortopulmonary fistula formation. Additionally, it is unclear what degree of RV hypertension and/or branch PA flow discrepancies are clinically significant in patients post ASO.