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(Circulation. 2002;106:I-40.)
© 2002 American Heart Association, Inc.

Surgery for Valvular Heart Disease

Mechanistic Insights Into Posterior Mitral Leaflet Inter-Scallop Malcoaptation During Acute Ischemic Mitral Regurgitation

David T. Lai, FRACS; Frederick A. Tibayan, MD; Truls Myrmel, MD; Tomasz A. Timek, MD; Paul Dagum, MD, PhD; George T. Daughters, MS; David Liang, MD, PhD; Neil B. Ingels, Jr, PhD; D. Craig Miller, MD

From the Department of Cardiovascular and Thoracic Surgery (D.T.L., F.A.T., T.M., T.A.T., P.D., G.T.D., N.B.I., D.C.M.), and Division of Cardiovascular Medicine (D.L.), Stanford University School of Medicine, Stanford, Calif.; Department of Cardiac Surgery, University Hospital, TROMSØ, Norway (T.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 and Thoracic Surgery, Falk Cardiovascular Research Center, Stanford University School of Medicine, Stanford, CA 94305-5247. E-mail dcm{at}stanford.edu

Background Three-dimensional dynamics of the 3 individual scallops within the posterior mitral leaflet during acute ischemic mitral regurgitations have not been previously measured.

Methods Radiopaque markers were sutured to the mitral annulus, papillary muscle tips, and leaflet edges in 13 sheep. Immediately postoperatively, under open-chest conditions, 3-D marker coordinates were obtained using high-speed biplane videofluoroscopy before and during echocardiographically verified acute ischemic mitral regurgitation produced by occlusion of the left circumflex coronary artery.

Results During acute ischemic mitral regurgitation, at end systole, the anterolateral edge of the central scallop was displaced 0.8±0.9 mm laterally and 0.9±0.6 mm apically away from the anterolateral scallop; such displacement correlated with lateral displacement of the lateral annulus (R²=0.7, SEE=0.7 mm, P<0.001) and movement of the right lateral annulus away from the nonischemic anterior papillary tip (R²=0.6, SEE=0.8 mm, P=0.002), respectively. End-systolic displacement of the posteromedial edge of the central scallop was 1.4±0.9 mm anteriorly and 0.9±0.6 mm laterally away from the posteromedial scallop, corresponding to anterior displacement of the mid-lateral annulus (R²=0.5, SEE=1.0 mm, P<0.001).

Conclusions Malcoaptation of the scallops within the posterior leaflet during acute left ventricular ischemia is a novel observation. The primary geometric mechanism underlying scallop malcoaptation in acute ischemic mitral regurgitation was annular dilatation, which hindered leaflet coaptation by drawing the individual scallops apart. These findings support the use of annular reduction in the repair of ischemic mitral regurgitation and also suture closure of prominent subcommissures between posterior leaflet scallops.

Key Words: Ischemic mitral regurgitation • mitral valve 3-D geometry • leaflet dynamics • posterior mitral leaflet • mitral scallops • ischemic heart disease • coronary artery disease