Advances in Experimental Percutaneous Pulmonary Valve Replacement

Abstract

Percutaneous pulmonary valve implantation is emerging as an alternative and additional option for a successful surgical scheme. To date, these procedures are performed by the balloon-in-balloon technique. The use of self-expanding stents for percutaneous valve replacement is assumed to improve preservation of the valve in its folded condition in the application device and the valve's long-term functioning. Therefore, initial experience with the development of a completely percutaneous transfemoral technique for pulmonary valve implantation using a self-expanding valved stent is described. Bovine jugular xenografts were sutured into nitinol stents, and functional in vitro tests of valved stents were carried out. Transfemoral implantation in pulmonary position was acutely evaluated in 6 sheep weighing 22 to 29 kg. Radiologic evaluation was performed by angiography and multislice computed tomography (MSCT) scan. In addition, pathoanatomical studies were performed. Exact implantation in pulmonary valve position was achieved in 5 of 6 sheep, with 1 early stent migration. Another sheep died before stent placement owing to perforation of the right ventricle by the delivery system. Orthotopic pulmonary valved stent position was depicted by MSCT in all other sheep (n = 4). The peak-to-peak transvalvular gradient was 8.2 +/- 3.9 mm Hg (n = 5). Postmortem examination revealed intact stent valves with no adherent clots. No macroscopic damage of the pulmonary artery was noted, whereas minor hematoma of the right atrium and the right ventricular outflow tract were observed in 2 hearts. This acute study demonstrates that memory nitinol valved stents can be optimally deployed in the pulmonary position through the groin in sheep.