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DOI: 10.1055/s-2006-925873
Percutaneous pulmonary valve replacement: Long-term evaluation of valved nitinol stents
Introduction: Percutaneous pulmonary valve implantation is emerging as an alternative or additional option for congenital surgery. To date, these procedures are performed by the balloon-in-balloon-technique with steel stents. The use of self-expanding stents for percutaneous valve replacement is assumed to improve preservation of the valve in its folded condition and the valve's long-term function. We evaluated the long-term outcome of percutaneously implanted pulmonary valves using self-expanding stents in an animal model.
Methods: Valved segments of bovine jugular veins were sutured into self-expanding nitinol stents. Implantation in pulmonary position was evaluated in seven sheep weighing 24 to 33kg. Through a modified commercially available delivery system (22 French) the self-expanding valved stents were implanted via the groin. Three months later, hemodynamic parameters were re-assessed, and radiological evaluation was performed by angiography and CT scan. In addition, patho-anatomical studies were carried out.
Results: One sheep died 2.5 months after the procedure due to vegetations on the neo-valve leading to subtotal stenosis. All other animals survived the three months study time (n=6). Orthotopic pulmonary valved stent position was achieved in five animals and supravalvular position in two. The peak-to-peak transvalvular gradient was 5.5±3.1mmHg initially (n=5), and 6.8±3.9mmHg at follow-up (n=5). Early and late angiographic studies confirmed competent neo-valves without paravalvular leakage. Postmortem examination revealed intact valved stents without adherent clots. There was no macroscopic damage of cardiac structures.
Conclusion: This study demonstrates for the first time good long-term function of percutaneously implanted valved nitinol stents in sheep.