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(Circulation. 2001;104:I-29.)
© 2001 American Heart Association, Inc.

Surgery for Valvular Heart Disease

Edge-to-Edge Mitral Repair

Tension on the Approximating Suture and Leaflet Deformation During Acute Ischemic Mitral Regurgitation in the Ovine Heart

Sten Lyager Nielsen, MD, PhD; Tomasz A. Timek, MD; David T. Lai, FRACS; George T. Daughters, MS; David Liang, MD, PhD; J. Michael Hasenkam, MD; Neil B. Ingels, PhD; D. Craig Miller, MD

Department of Cardiothoracic and Vascular Surgery and Institute of Experimental Clinical Research, Aarhus University Hospital–Skejby Sygehus, Aarhus, Denmark (S.L.N., J.M.H.); Department of Cardiovascular and Thoracic Surgery, Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, Calif (T.A.T., D.T.L., G.T.D., D.L., N.B.I., D.C.M.); and Laboratory of Cardiovascular Physiology and Biophysics, Research Institute of the Palo Alto Medical Foundation, Palo Alto, Calif (G.T.D., N.B.I.).

Correspondence to D. Craig Miller, MD, Department of Cardiovascular Surgery, Falk Cardiovascular Research Center, Stanford University School of Medicine, Stanford, CA 94305-5247. E-mail dcm{at}stanford.edu

Background— Edge-to-edge approximation of the mitral valve leaflets (Alfieri procedure) is a novel surgical treatment for patients with ischemic mitral regurgitation (IMR). Long-term durability may be limited if abnormal mitral leaflet stresses result from this procedure. The aim of the current study was to measure Alfieri stitch tension (F_A) and to explore its geometric determinants in an ovine model of acute IMR as a reflection of the mitral leaflet stresses imposed by the procedure.

Methods and Results— Eight sheep were studied immediately after surgical placement of (1) a force transducer interposed between sutures approximating the central leaflet edges and (2) radiopaque markers around the mitral annulus and leaflet edges. Computer-aided analysis of videofluorograms was used to obtained 3D marker coordinates. Simultaneous measurements of F_A, septal-lateral annular dimension (L_S-L), leaflet edge separation (L_SEP), anterior (L_AL) and posterior (L_PL) leaflet length, and hemodynamic variables were obtained at baseline (CTL) and during acute IMR (circumflex artery occlusion). F_A was significantly elevated throughout the cardiac cycle during IMR compared with CTL, with maximum F_A in diastole (0.26±0.05 versus 0.46±0.08 N, CTL versus IMR; P<0.05). Multivariable analysis revealed L_S-L as the single independent predictor of maximum F_A (P<0.001). Positive linear correlations were shown between values of F_A and L_AL and L_PL (dependent variables).

Conclusions— These experimental data demonstrate higher F_A during IMR and cyclic changes in F_A closely paralleling changes in L_S-L, eg, being greatest in diastole when the annulus is largest. Increased F_A during IMR is probably indicative of successful therapeutic intent, but higher diastolic leaflet stresses resulting from persistent or progressive mitral annular dilatation may adversely affect repair durability. This indirectly implies that concomitant mitral ring annuloplasty should be added to the Alfieri repair.

Key Words: mitral valve • valvuloplasty • coronary disease