Key result
Septal-lateral annular cinching reduces end-systolic mitral annular area by ~11% and alters LV geometry.
Why the study?
Although etiology-specific annular interventions and annuloplasty rings are commercially available for treating different types of mitral regurgitation, knowledge regarding how local annular alterations affect mitral annular and LV geometry was limited.
Demonstrates that localized septal-lateral annular cinching reduces overall annular area and modifies left ventricular geometry in ovine models, highlighting biomechanical impacts on repair design.
OBJECTIVE: Etiology-specific annular interventions and annuloplasty rings are now commercially available for the treatment of different types of mitral regurgitation; however, knowledge concerning the effects of local annular alterations on annular and left ventricular (LV) geometry is limited. METHODS: Seven adult sheep underwent implantation of eight radiopaque markers around the mitral annulus (MA) and eight markers on the LV (four each on two levels: basal and apical), and one on each papillary muscle tip. Trans-annular septal-lateral (SL) sutures were placed between the corresponding markers on the septal and lateral annulus at valve center (CENT) and near anterior (ACOM) and posterior (PCOM) commissures and externalized. Hemodynamic parameters and 4D marker coordinates were measured before and during SL annular cinching ('SLAC'; suture tightening 3-5 mm for 20s) at each suture location. Mitral annular SL diameter, annular area (MAA), and distance from the mid-septal annulus to the LV markers and papillary muscle tips were determined from marker coordinates every 17ms. RESULTS: End-systolic MAA decreased from 5.93+/-1.27 to 5.23+/-1.29(*)cm(2), 5.98+/-1.16 to 5.33+/-1.31(*)cm(2), and 6.30+/-1.65 to 5.61+/-1.37(*)cm(2) for SLAC(ACOM), SLAC(CENT), and SLAC(PCOM), respectively ((*)p<0.05 vs pre-cinching). Each SLAC intervention reduced the SL diameter at all three locations, while both SLAC(ACOM) and SLAC(CENT) affected ventricular geometry, and SLAC(PCOM) only slightly altered valvular-subvalvular distance. Only SLAC(CENT) altered papillary muscle position. CONCLUSIONS: Local annular SL reduction influences remote annular SL dimensions and affects LV geometry. The effect of local annular interventions on global annular geometry and LV remodeling should be considered in surgical or interventional approaches to mitral regurgitation and the design of new annular prostheses as well as supra-annular and sub-annular catheter interventions.
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Timek et al. (2008) studied Mitral regurgitation (experimental ovine model) (n=7). Septal-lateral annular cinching (SLAC) at anterior commissure, valve center, and posterior commissure vs. Pre-cinching baseline was evaluated on End-systolic mitral annular area (MAA, cm2) for central cinching (SLAC CENT) (p=<0.05). Septal-lateral annular cinching significantly reduced end-systolic mitral annular area across all three locations (e.g., center: 5.98 to 5.33 cm2, p<0.05) and altered LV geometry.
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