Surgical technique
Following median full sternotomy, cardiopulmonary bypass was routinely established by aortic and bicaval cannulation, and the mitral valve was exposed via a right-sided left atriotomy under cardioplegic arrest. Complete debridement of the infective and destructive valve tissue was performed first (Figure 1a). Fresh autologous pericardium was harvested and trimmed to an appropriate size corresponding to the mitral valve defect. The size of the harvested pericardium was slightly larger than the size of the mitral valve defect, with a 5-mm-wide seam allowance. The mitral valve was then reconstructed with this fresh autologous pericardium. The base of the patch was attached to the mitral annulus with 4-0 polypropylene running sutures, and the side edges of the patch were sutured to the remnant of the leaflet tissues with 5-0 polypropylene sutures (Figure 1b). As artificial chordae, 5-0 double-armed polytetrafluoroethylene sutures (Gore-Tex; W. L. Gore & Associates, Newark, DE, USA) were placed to the free edge of the reconstructed pericardium if needed (Figure 1c). Finally, mitral annuloplasty with a prosthetic ring was performed (Figure 1d). The prosthetic ring size was routinely determined according to the inter-trigonal distance and anterior leaflet height.