Abstract 13552: How do Annuloplasty Rings Affect Mitral Annular Strains in the Beating Ovine Heart?
Introduction: We hypothesized that annuloplasty ring implantation alters mitral annular strains in a beating ovine heart preparation.
Methods: Sheep had 16 radiopaque markers sewn equally spaced to the mitral annulus. Edwards Cosgrove partial flexible band (COS, n=12), St. Jude complete rigid saddle-shaped annuloplasty ring (RSA, n=10), and Carpentier-Edwards Physio (PHY, n=11), IMR ETlogix (ETL, n=11), and GeoForm (GEO, n=12) annuloplasty rings were implanted in a releasable fashion. Four-dimensional marker coordinates were obtained using biplane videofluoroscopy with the ring inserted (R) and after ring release (C) at end-diastole (ed) and end-systole (es). From marker coordinates, a functional spatio-temporal representation of each annulus was generated through a best fit using 16 piecewise cubic Hermitian splines. Mitral annular strains were calculated as the relative change in length tangent to the annular curve as: 1) cardiac cycle strains (ed to es) with ring (edR-esR) and without ring (edC-esC) as well as 2.) ring strains, i.e. strains with ring implanted compared to Control at ed and es (edC-edR and esC-esR, respectively).
Results: Cardiac cycle strains were significantly smaller with any of the rings implanted (edC-esC vs. edR-esR, Fig, A). Ring strains were: 1.) Significantly greater than cardiac cycle strains with no ring implanted (edC-edR and esC-esR vs. edC-esC, Fig, A/B); 2.) Smallest for COS and greatest for ETL at es (Fig, B); 3.) greatest along the posterior commissure and lateral annulus (Fig, D).
Conclusions: In healthy, beating ovine hearts, annuloplasty rings (COS, RSA, PHY, ETL and GEO) reduce mitral annular cardiac cycle strains and induce ring strains that are: 1.) greater than cardiac cycle strains without ring; 2.) predominant in the posterior and lateral annular regions; 3.) smallest with flexible partial bands (COS) and greatest for flat, asymmetric rigid rings with intrinsic septal-lateral downsizing (ETL).
- © 2011 by American Heart Association, Inc.