Static analysis of annuloplasty rings sutured on an annulus model of the mitral valve: Comparison between the Duran ring and the Carpentier Classic ring

A novel in vitro evaluation system was developed to study the performance of newly developed and conventional annuloplasty rings. Using this system, a comparative study between the Duran flexible ring and the Carpentier Classic (rigid) ring was conducted with the aim of achieving a better understanding of these devices and of providing surgeons with better criteria for selecting the most appropriate annuloplasty ring. It was possible to obtain quantitative data using a microscope and a load cell to measure valve orifice area and tensile load on the valve annulus, respectively. Among the results were the findings that the orifice area of the rigid ring was smaller by 12.0% than that of the flexible ring and that in both rings the load was greater in the posterior region than in the anterior region. Further analysis using a beam model demonstrated that the stress applied to the sutures of the rigid ring is higher than that for the flexible ring in terms of shearing force and bending moment of the ring. This pilot study yielded several important findings: the ability of a ring to maintain valve orifice area is observable; larger loads are applied to the posterior annulus than to the anterior annulus; and it is possible to clarify and compare the characteristics of various types of annuloplasty rings.