Minimally invasive off-pump valve-in-a-valve implantation: the atrial transcatheter approach for re-operative mitral valve replacement

Aims This study was designed to evaluate the feasibility and haemodynamic performance of transcatheter valve-in-a-valve (VinV) implantation for failed mitral xenografts using a minimally invasive, transatrial, off-pump approach. Methods and results Nine adult sheep (71.1 +/- 3.4 kg) underwent mitral valve replacement with a 25 mm bioprosthesis using standard conventional techniques. After weaning from cardiopulmonary bypass, a transcatheter 23 mm pericardial prosthesis mounted on a balloon-inflatable steel stent was deployed within the conventional xenograft. The VinV implantation (10.1 +/- 0.9 min) was performed off-pump using an antegrade transatrial approach under fluoroscopic guidance successfully in all nine sheep. Mean transvalvular gradient was 4.6 +/- 1.0 mmHg, and five of nine sheep had no paravalvular leak with two sheep each having mild and moderate one. All transcatheter prostheses were confirmed in good position on post-mortem analysis. In an in vitro model, the minimum force required to dislodge the valve was 22.5 +/- 3.0 N, which was well above the normal estimated forces generated by the left ventricle (LV). When this model was attached to a LV assist device, the VinV withstood pressure loops of 300 mmHg, without dislocation or embolization. Conclusion Transatrial, transcatheter mitral VinV implantation is feasible off pump. This is a truly minimally invasive concept to treat patients with failed xenografts using a right lateral minithoracotomy.