A Novel Balloon-Expandable Stenting By Hybrid Procedure For The Management Of Pulmonary Artery Stenosis In A Swine Model

Objectives:(1) To evaluate the effectiveness of autologous pericardium applied to pulmonary artery banding in a swine model.(2) To evaluate the effectiveness of implantation of balloon-expandable stent into stenotic pulmonary artery in a swine model., and also to summarize the application of hybrid procedures for the management of pulmonary artery stenosis in a swine model.Methods:(1) In a swine model, pulmonary artery stenosis was created by autologous pericardium which made the left pulmonary artery banded to30%～40%of its original diameter. Animals underwent right heart catheterization and angiography4weeks postoperatively, and balloon-expandable stents were implanted through right ventricular outflow tract (RVOT). The animals were sacrificed at12-weeks following stenting and microscopic evaluation for histologic changes was made.(2) In a swine model, pulmonary artery stenosis was created by banding the left pulmonary artery to30%～40%of its original diameter. Animals underwent right heart catheterization and angiography4weeks postoperatively, and Cobalt-Chromium alloy stents were implanted through right ventricular outflow tract. The animals were sacrificed at4-weeks and12-weeks following stenting and microscopic evaluation for histologic changes was made.Results:(1) Pulmonary artery banding was performed in8swines. The lumen diameter decreased from (16.0±0.4) mm to (6.4±0.2) mm (Mean±SD)(P<0.001) while the gradient increased from median (range)0mmHg to35(18～52) mmHg (P<0.001) following banding.1month later, the models were all survived.Compared to the instant result after banding,it was no significant difference in the lumen diameter(P=0.697) or the gradient (P=0.672), and there was no banding dislodged and also no animals with severe left pulmonary artery hypoplasia or atresia.(2) Hybrid stent implantation was performed in8swines with pulmonary artery stenosis. The lumen diameter increased from (6.4±0.2) mm to (15.6±0.4) mm (P<0.01) while the gradient decreased from median (range)34.5(23～52) mmHg to6(1～20) mmHg (P=0.012) following stenting. There were no stents dislodgement and no significant vessel tears or ruptures by12-week follow-up. The scanning electron microscope findings appeared well endothelialization and no stent malapposition. Although stents with neointimal proliferation were observed by scanning electron microscope in2animals at12weeks, there was no significant hemodynamic difference between two groups.Conclusions:(1) Autologous pericardium acts as a banding to create an experimental pulmonary artery stenosis model appears safe and effective.(2) The novel balloon-expandable stent implanted in experimental pulmonary artery stenosis model appears safe and effective. Meanwhile, the hybrid procedure can avoid cardiopulmonary bypass (CPB) and minimize surgical trauma, being an effective option for the management of pulmonary artery stenosis.