Implantation of a modified stented bovine pulmonary valve in a beating heart sheep model.

ABSTRACT

PURPOSE: The aim of this research was to assess the performance of a modified bovine stent valve implanted transventricularly in the pulmonary position in sheep with a 3-month follow-up period. MATERIALS AND METHODS: Seven modified pulmonary bovine stent valves were transventricularly implanted in the pulmonary position into seven sheep using a delivery system. Stent valve performance was investigated and evaluated hemodynamically, angiographically, and with echocardiograms before, immediately after, and 3 months following implantation. Macroscopic, histologic, and radiographic examinations were performed on the explanted graft at 3 months. RESULTS: The modified stent valves were all deployed and implanted successfully in the pulmonary position in seven sheep. Angiographic, echocardiographic, hemodynamic, and macroscopic analyses confirmed firm anchoring of the stents in the target position in the early and 3-month follow-up period. All modified stent valves showed satisfactory function, except one moderate stenosis (32 mmHg gradient) with mild regurgitation that was discovered at 3 months. All seven valves were free of any calcification and thrombus formation at postmortem macroscopic examination, which was confirmed by histologic and radiographic examination. All stents were intact without any fracture at microscopic or radiographic examination. CONCLUSIONS: Transventricular implantation of a modified nitinol pulmonary valve stent showed good structural and functional outcomes without stent fracture or migration.