Which valve and which size should we use in the valve-on-valve technique for re-do mitral valve surgery?

The valve-on-valve (VOV) technique is that a mechanical valve is implanted on the sewing cuff of the previous bioprosthesis after removing degenerated leaflets. We conducted an in vitro study to determine the size-match of the valves for VOV technique. The Carpentier-Edwards pericardial (CEP) valve and Mosaic valve were used. We measured the inner diameter of the bioprosthesis after removing the leaflets. We investigated five mechanical mitral valves and two mechanical aortic valves (inverted use). The mitral valves used in this study were the ATS valve (ATS), the CarboMedics standard valve (CMS), the CarboMedics OptiForm valve (CMO), the On-X valve, and the St Jude valve (SJM). Two aortic mechanical valves, CarboMedics and St Jude Regent valves, were investigated for inverted use. After removing the tissue leaflets, the inner diameter of the Mosaic valve was 3 mm smaller than that of the CEP valve even in the same catalogue labeling size. The outer diameters of the housing of the ATS, CMS, CMO, On-X, and SJM valves of the same catalogue size (25 mm) were 25.7, 25.8, 22.0, 25.0, and 23.2 mm, respectively. SJM and CMO valves are the favorite mechanical valve for the VOV technique in terms of the profile and size-match.