|Ideal Pathoanatomy||Challenging Pathoanatomy||Relative Pathoanatomic Contraindications|
|Primary lesion location||Posterior leaflet only||Anterior leaflet or bileaflet||None|
|Leaflet calcification||None||Mild||Moderate to severe|
|Annular calcification||None||Mild to moderate with minimal leaflet encroachment||Severe or with significant leaflet encroachment|
|Subvalvular apparatus||Thin, normal||Mild diffuse thickening or moderate focal thickening||Severe and diffuse thickening with leaflet retraction|
|Mechanism of MR||Type II fibroelastic deficiency or focal myxomatous prolapse or flail||Type II forme fruste or bileaflet myxomatous (Barlow’s) disease; Type I healed or active endocarditis; Type IIIA/B with mild restriction or leaflet thickening||Type IIIB with severe tethering and inferobasal aneurysm; Type IIIA with severe bileaflet calcification; Type I active infection with severe leaflet or annular tissue destruction|
|Unique anatomic complexities||None||Redo cardiac operation or mitral re-repair; anatomic predictors of systolic anterior motion (e.g., septal hypertrophy); adult congenital anomalies; focal papillary muscle rupture||Mitral valve reoperation with paucity of leaflet tissue; diffuse radiation valvulopathy; papillary muscle rupture with shock|
MR = mitral regurgitation.