Chronic haemodynamic performance of a biorestorative transcatheter heart valve in an ovine model

Background: The Xeltis biorestorative transcatheter heart valve (BTHV) leaflets are made from an electrospun bioabsorbable supramolecular polycarbonate-urethane and are mounted on a self-expanding nitinol frame. The acute haemodynamic performance of this BTHV was favourable. Aims: We sought to demonstrate the preclinical feasibility of a novel BTHV by evaluating the haemodynamic performances of five pilot valve designs up to 12 months in a chronic ovine model. Methods: Five design iterations (A, B, B', C, and D) of the BTHV were transapically implanted in 46 sheep; chronic data were available in 39 animals. Assessments were performed at implantation, 3, 6, and 12 months including quantitative aortography, echocardiography, and histology. Results: At 12 months, greater than or equal to moderate AR on echocardiography was seen in 0%, 100%, 33.3%, 100%, and 0% in the iterations A, B, B', C, and D, respectively. Furthermore, transprosthetic mean gradients on echocardiography were 10.0 +/- 2.8 mmHg, 19.0 +/- 1.0 mmHg, 8.0 +/- 1.7 mmHg, 26.8 +/- 2.4 mmHg, and 11.2 +/- 4.1 mmHg, and effective orifice area was 0.7 +/- 0.3 cm(2), 1.1 +/- 0.3 cm(2), 1.5 +/- 1.0 cm(2), 1.5 +/- 0.6 cm(2), and 1.0 +/- 0.4 cm(2) in the iterations A, B, B', C, and D, respectively. On pathological evaluation, the iteration D demonstrated generally intact leaflets and advanced tissue coverage, while different degrees of structural deterioration were observed in the other design iterations. Conclusions: Several leaflet material iterations were compared for the potential to demonstrate endogenous tissue restoration in an aortic valve in vivo. The most promising iteration showed intact leaflets and acceptable haemodynamic performance at 12 months, illustrating the potential of the BTHV.