Feasibility of Stent Fracture and Expansion in the Palliation of Branch Pulmonary Artery Stenosis

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Branch pulmonary artery stenosis (BPAS) is a common consequence of the repair of congenital heart disease in pediatric patients. Although a small stent may be placed to relieve the BPAS, this intervention is temporary as these patients will eventually outgrow the stent. The purpose of our study was to investigate the feasibility of a proposed method of catheter‐based palliation of BPAS with 1) placement of a small stainless steel stent followed by 2) repeat catheterizations with sequential dilation and eventual fracturing of the stent and 3) restenting of the BPAS with a larger, expandable stent. We first compared the bench‐top fracture pattern of the 5mm Paramount Mini GPS stent with the in‐vivo fracture pattern in a piglet model of BPAS in which a 4 mm Gortex band was placed around the left pulmonary artery at 3 weeks of age. The 5 mm stent fractured on its horizontal axis at 12 mm and 12 ATM and the vertical axis at 14 mm and 16 ATM. In‐vivo, a 7 mm Paramount stent was placed two weeks post‐surgical creation of the BPAS and expansion was performed at 7 and 11 weeks (73kg). This stent also fractured on it horizontal axis after dilation to 12 mm diameter but was unable to be fractured on the vertical axis despite high pressure balloon dilation to 16 mm and 20 ATM. The stent substantially for‐shortened without vertical fracture, documented with fluoroscopy and necropsy. In subsequent studies to be presented here, we will examine the impact of restenting and subsequent stent expansion on vascular growth and right heart function.