A novel dual-orifice mitral bioprosthesis: Proof-of-concept in an ovine model

Conventional large mitral bioprostheses may cause left ventricular outflow tract obstruction. A dual-orifice mitral bioprosthesis was designed for both surgical and transcatheter valve replacement.

Pulsatile flow testing was used to measure the effective orifice area (EOA). Computational fluid dynamics analysis was conducted to assess thrombogenic and hemolysis risk. An ovine model was used to evaluate procedural safety, hemodynamic performance, and leaflet calcification.

Pulsatile flow testing showed that the EOAs of surgical dual-orifice valve (17K, 18K, 19K, 20K, 21K) were 2.0 ± 0.2, 2.1 ± 0.3, 2.4 ± 0.4, 2.5 ± 0.1, and 2.7 ± 0.3 cm² under 5 L/min cardiac output, respectively. The mean hemolysis index and platelet activation state of 19K surgical dual-orifice valve under 7 L/min cardiac output were 1.3 × 10^-8 and 2.2 × 10^-8 in the computational fluid dynamics analysis, respectively. Six ovine underwent implantation of the 19K surgical dual-orifice valve and were followed for 20 weeks. The mean pressure gradient and EOA were 3.7 ± 0.8 mm Hg and 2.7 ± 0.3 cm² immediately after implantation and 5.0 ± 2.3 mm Hg and 2.5 ± 0.2 cm² at 20 weeks, respectively. One ovine was implanted the 19K transcatheter dual-orifice valve and followed up for 125 days. The mean pressure gradient was 5.0 mm Hg immediately after implantation and 3.0 mm Hg at the end point.

The dual-orifice mitral bioprosthesis may represent an alternative design for mitral valve replacement, especially for patients with large mitral annuli. This findings also show the potential of this design in transcatheter mitral valve replacement.