BACKGROUND: Selectively flexible rings, Colvin-Galloway (CG) Future and Carpentier-Edwards (CE) Physio II, are used for annuloplasty during mitral valve repair to facilitate dynamic annular motion while preventing annular dilation. In this study, we assessed the extent and nature of the flexibility of these rings in vivo, which has not been objectively demonstrated. METHODS: Three-dimensional transesophageal echocardiography was used intraoperatively to acquire data regarding dynamic motion of mitral annuli and annuloplasty rings in 33 patients undergoing mitral repair (15 CG Future and 18 CE Physio II) and in 15 control patients. Data were analyzed to assess the dynamic changes in annular geometry after implantation of selectively flexible rings. RESULTS: After annuloplasty, there was an immediate and significant decrease in annular displacement (p 0.001) and annular displacement velocity (p 0.01). Dynamic change in multiple variables including anteroposterior diameter (p 0.001) and annular area (p 0.001) was also significantly depressed. In comparison with normal mitral valves, partially flexible rings allowed limited dynamic motion: percentage changes in anteroposterior diameter (p 0.001), anterolateral posteromedial diameter (p 0.001), and total circumference (p 0.001) were significantly lower. Compared with each other, the two rings resulted in similar changes in anterior annulus length (p = 0.93), posterior annular length (p = 0.82), and annular area (p = 0.31). CONCLUSIONS: Mitral annular dynamics were uniformly depressed after implantation of these rings. Selective flexibility could not be demonstrated in vivo using echocardiographic data.