Percutaneous pulmonary valve replacement: polyurethane valved stent implantation

Background: Transfemoral application of pulmonary heart valves has been recently introduced clinically. Nevertheless, size restriction of percutaneous heart valved stent are still immanent.

Methods: In this study we implanted percutaneously a novel low-profile polyurethane valved stent. Percutaneous implantation in pulmonary position was evaluated in 7 sheep. The new valved stent fits into a 14-French delivery device. The self-expanding nitinol stent was produced by a dip coating technique and a modified commercially-available endovascular stent-graft system served as a delivery device. The valved stents were deployed directly over the native pulmonary valve under fluoroscopic control. Thransthoracic echocardiography was done after 4 weeks. At the time of explantation the animals were reanalyzed and sacrificed. Angiography was performed at implantation and at the end of the study. Explanted constructs were analyzed macros- and microscopically.

Results: Angio- and echocardiography in all animals demonstrated orthotopic position of the stents at the time of implantation and after 4 weeks. During the deployment procedure, rhythm disturbances occurred in all animals. The peak-to-peak transvalvular gradient was 2.3±1.2mmHg initially, and 4.1±2.4mmHg at follow-up (p=ns). One-month-follow-up confirmed competent neovalves without any paravalvular leakage. Gross morphology demonstrated good opening and closure characteristics. No calcification was seen macroscopically and surrounding tissue was also free of calcification.

Conclusion: In the present study we demonstrated successful merging of two novel technologies for percutaneous treatment of pulmonary valve diseases using polyurethane stented valve constructs