Entire mitral valve reconstruction using porcine extracellular matrix: static in vitro evaluation

To investigate the feasibility of reconstruction of the entire mitral valve using a tube graft made of 2-ply small intestinal submucosa extracellular matrix in vitro.

Seven explanted mitral valves with intact subvalvular apparatus from 80 kg pigs were evaluated in a left heart simulator and served as controls. After testing the native valve, the leaflets and chordae tendineae were explanted, and the 2-ply small intestinal submucosa extracellular matrix (CorMatrix®; Cardiovascular Inc., Alpharetta, GA, USA) tube graft was implanted. The characterization was based on geometric data from digital images, papillary muscle force, annular tethering force and leaflet pressure force.

The tube grafts were fully functional without any signs of leakage, tearing or rupture during incrementally increased pressures from 0 mmHg to 120 mmHg. The posterior leaflet moved anteriorly and became larger after reconstruction when compared with the native valve. However, the mid coaptation point was preserved. The anterior papillary muscle force decreased significantly (5.2 N vs 4.4 N, P = 0.022 at 120 mmHg), and the posterior papillary muscle force increased significantly (4.8 N vs 5.6 N, P = 0.017 at 120 mmHg) after reconstruction.

The entire mitral valvular and subvalvular reconstruction with a 2-ply small intestinal submucosa extracellular matrix tube graft is feasible in an in vitro model. Our method of reconstruction increased the convexity of the anterior leaflet's coaptation line and significantly redistributed the papillary muscle force towards the posterior papillary muscle. These promising results and the prospect of the entire mitral valvular and subvalvular reconstruction warrant further in vivo evaluations.