Abstract 3177: Saddle-shaped Mitral Valve Annuloplasty Rings Improve Leaflet Coaptation Geometry
Introduction: The mitral valve annulus naturally conforms to a saddle-shape in systole. This configuration is believed to set the leaflets in a lower-energy equilibrium with the annulus and subvalvular apparatus. Conventional flat annuloplasty rings restrict posterior leaflet motion which may result in a “mono-cusp” valve, affecting valvular stress distribution.
Hypothesis: Saddle-shaped annuloplasty rings cause less distortion of the physiologic leaflet geometry compared with flat rings.
Methods: Ten animals were studied in an acute porcine in vivo model with 3D echocardiography and sonomicrometry before and after implantation of dedicated rigid flat and saddle-shaped annuloplasty rings. Anterior-posterior and commissure-commissure dimensions of the rings were equal. The saddle-shaped rings had an annular height to commissural width ratio of 15%.
Results: Saddle-shaped rings maintained dual leaflet operation, although leaflet geometry relative to the annular plane resulted in decreased height, area, and angles (Fig⇓.). Following flat ring implantation, the posterior leaflet became immobile and the anterior leaflet aligned flat along the annulus in systole. The average distance from the papillary muscles to the posterior annulus decreased by 2.4 ± 0.4 mm and 1.4 ± 0.3 mm following flat and saddle-shaped ring implantation, respectively (p<0.01).
Conclusions: Saddle-shaped annuloplasty rings provide superior leaflet coaptation geometry compared with flat rings, potentially having a beneficial impact on valvular stress distribution and repair durability. Annular and subvalvular geometric relationship can be a contributing factor to these results.