Effects of different annuloplasty ring types on mitral leaflet tenting area during acute myocardial ischemia

Abstract

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.

How Do Annuloplasty Rings Affect Mitral Annular Strains in the Normal Beating Ovine Heart?

“…First, images were acquired under baseline conditions with the ring inserted (Ring, R). As reported earlier, a brief period of ischemia (90 seconds) was then induced and another dataset with ring and ischemia was acquired [7]. After hemodynamics returned to normal values, the ring was released and data were acquired under baseline conditions without ring (Control, C).…”

Rigid, Complete Annuloplasty Rings Increase Anterior Mitral Leaflet Strains in the Normal Beating Ovine Heart

“…All annuloplasty devices were true-sized (as all animals had similarly sized leaflets, each received size 28 rings or bands). The left atrium (LA) was closed and the left circumflex artery (LCx) was encircled with a vessel loop for a parallel study [9]. Data from mitral annular and leaflet geometry using this dataset have been published earlier [8-11].…”

Characterization of Mitral Valve Annular Dynamics in the Beating Heart

“…For biplane videofluoroscopic imaging, we transferred the animals to the experimental catheterization laboratory 1-2 h after weaning them off of cardiopulmonary bypass. After acquiring the data set for a separate study, acute ischemia with 90s of LCx occlusion, 3 we recorded 3D marker coordinates in the beating heart at a sampling frequency of 60 Hz under open chest conditions in the right lateral decubitus position. In order to prevent ventricular fibrillation, we administered a loading dose of lidocaine (1 mg/kg IV) followed by a lidocaine infusion (1 mg/min) along with bretylium (75 mg IV) and magnesium (3 g IV).…”