Restricted posterior leaflet motion after mitral ring annuloplasty

Background. The effects of ring annuloplasty on mitral leaflet motion are incompletely known. The three-dimensional dynamics of the mitral valve in vivo were examined to determine how two types of annuloplasty rings affect leaflet motion during valve closure. Methods. Miniature radiopaque markers on the mitral leaflets, annulus, and left ventricle were implanted in three groups of sheep. One group served as control (n = 7); other sheep were randomly assigned to receive either a flexible Duran (n = 6) or a semirigid Carpentier-Edwards Physio ring (n = 6). After recovery, three-dimensional marker coordinates were computed from simultaneous (60 Hz) biplane videofluoroscopic marker images. Results. Both types of rings immobilized the middle scallop of the posterior leaflet without affecting anterior leaflet motion. The excursion of the anterior leaflet edge from maximally open to fully closed was not different between the groups (control, 13 ± 2 mm; Duran 13 ± 1 mm; Physio ring, 14 ± 1 mm; p> 0.05), but posterior leaflet edge excursion was restricted (control, 7.4 ± 0.4 mm; 2.3 ± 0.3 mm [p< 0.001]; Physio, 2.7 ± 0.2 mm [p< 0.001]) by both rings. Conclusions. Mitral annuloplasty with either ring type markedly reduced the mobility of the central posterior leaflet in normal ovine hearts such that valve closure became essentially a single (anterior) leaflet process with the frozen posterior leaflet serving only as a buttress for closing.