OBJECTIVE
To quantify effects of different annuloplasty rings on mitral leaflet septal-lateral (S-L) tenting areas (TAs) during acute myocardial ischemia.
METHODS
Radiopaque markers were implanted in 30 sheep: two to the S-L aspects of the mitral annulus; four and two along the central S-L meridian of anterior and posterior mitral leaflet (AML, PML), respectively. Ten true-sized Carpentier-Edwards Physio (PHYSIO), Edwards IMR-ETLogix (ETL) and GeoForm (GEO) annuloplasty rings were inserted in a releasable fashion. Marker coordinates were obtained using biplane videofluoroscopy with ring inserted, at baseline (RING_BL), and after 90s of LCx occlusion (RING_ISCH). After ring release, another dataset was acquired before (No_Ring_BL) and after LCx occlusion (No_Ring_ISCH). AML and PML 3-D TAs were computed at mid-systole from sums of marker triangles with the midpoint between the annular markers being the vertex for all triangles.
RESULTS
Compared to No_Ring_BL, MR grades and all TAs significantly increased with No_Ring_ISCH. Relative to No_Ring_ISCH: 1.) All rings significantly prevented MR and reduced all TAs; 2.) ETL and GEO reduced PML, but not AML TA to a significantly greater extent than PHYSIO; and, 3.) ETL and GEO affected TAs similarly.
CONCLUSIONS
In response to acute LV ischemia, disease specific FMR/IMR rings (ETL, GEO) more effectively reduced PML, but not AML TA compared to true-sized physiological rings (PHYSIO). Despite its radical 3-D shape and greater amount of mitral annular S-L downsizing, GEO did not reduce TAs more than ETL, suggesting that further reduction in TAs may not be effectively achieved using annular size reduction.