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(Circulation. 2003;108:II-116.)
© 2003 American Heart Association, Inc.

Surgery for Valvular Heart Disease

Geometric Distortions of the Mitral Valvular-Ventricular Complex in Chronic Ischemic Mitral Regurgitation

Frederick A. Tibayan, MD; Filiberto Rodriguez, MD; Mary K. Zasio, BS; Lynn Bailey, AS; David Liang, MD, PhD; George T. Daughters, MS; Frank Langer, MD; Neil B. Ingels, Jr, PhD; D. Craig Miller, MD

From the Department of Cardiovascular and Thoracic Surgery, Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, California, and Laboratory of Cardiovascular Physiology and Biophysics, Research Institute of the Palo Alto Medical Foundation, Palo Alto, California

Correspondence to D. Craig Miller, M.D., Department of Cardiovascular and Thoracic Surgery, Falk Cardiovascular Research Center, Stanford University School of Medicine, Stanford, CA 94305-5247. Phone: 650-723-3826, Fax: 650-725-3846, E-mail: dcm{at}stanford.edu

Background— Better understanding of the precise 3-dimensional geometric changes of the mitral valvular-ventricular complex in chronic ischemic mitral regurgitation (CIMR) is needed in order to devise better surgical repair techniques. We hypothesized that changes after inferior myocardial infarction would be different in hearts that developed CIMR compared with those that did not.

Methods and Results— Twenty-four sheep underwent coronary snare and marker placement (annulus, papillary muscles, and anterior and posterior leaflets). After 8 days, cinefluoroscopy provided 3-dimensional marker data, and snare occlusion of obtuse marginal branches created inferior myocardial infarction, including the posterior papillary muscle. After 7 weeks, the 16 surviving animals were studied again and grouped by mitral regurgitation grade ( 2+, n=10 versus 1+, n=6). End-systolic mitral annulus dimensions, components of papillary muscle and leaflet displacement, were calculated. After inferior myocardial infarction, total displacement of the posterior papillary muscle from the midseptal annulus ("saddle horn") was greater in CIMR(+) animals: 6.5±3.2 versus 3.1±2.7 (P=0.02), with the posterior papillary muscle moving more laterally (6.8±3.4 versus 2.5±3.5 mm, P=0.01). Increase in mitral annular septal-lateral diameter was greater in animals with CIMR (4.9±2.7 versus 2.3±2.0, P=0.02), and apical displacement of the posterior leaflet (PL) margin was also greater in the CIMR(+) group (1.7±1.0 versus 0.3±0.5, P=0.01).

Conclusions— The CIMR(+) group had greater septal-lateral annular dilatation, lateral posterior papillary muscle displacement, and apical PL restriction, indicating that these associated geometric alterations may be important in the pathogenesis of CIMR. Treatment of CIMR should address both annular septal-lateral dilatation and lateral displacement of the posterior papillary muscle.

Key Words: mitral regurgitation • ischemic mitral regurgitation • mitral annuloplasty • mitral valve repair • myocardial ischemia • ischemic heart disease