title: Mechanistic insights into functional mitral regurgitation.
abstract: Effective valve repair in patients with mitral regurgitation (MR) demands an understanding of its mechanism. In patients with ischemic heart disease and functional MR, which doubles late mortality, normal leaflets are apically displaced. This reflects an altered balance of forces acting on the leaflets: increased tethering forces restricting closure, resulting from an altered geometry of leaflet attachments, and decreased ventricular forces acting to close the leaflets. Extensive evidence confirms a central and predominant role of tethering as the final common pathway inducing functional MR; left ventricular (LV) pressure dynamically modulates the orifice area. Because ischemic MR is a disease of the entire mitral complex, including the remodeling LV, reducing annular size alone is often ineffective. Undersizing rings attempts to compensate for tethering; new and potentially more effective strategies directly address tethering by infarct plication, papillary muscle repositioning with a localized patch, or basal chordal cutting to increase coaptational surface area without prolapse. A comprehensive understanding of the valve in its ventricular context, therefore, provides new opportunities for successful valve repair in patients.
authors.affiliation: Massachusetts General Hospital, Department of Medicine, Non-Invasive Cardiology Laboratory VBK508, 55 Fruit Street, Boston, MA 02114, USA. rlevine@partners.org
authors.forename: Robert A
authors.initials: RA
authors.lastname: Levine
authors.forename: Judy
authors.initials: J
authors.lastname: Hung
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Otsuji
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Messas
authors.forename: Noah
authors.initials: N
authors.lastname: Liel-Cohen
authors.forename: Nadia
authors.initials: N
authors.lastname: Nathan
authors.forename: Mark D
authors.initials: MD
authors.lastname: Handschumacher
authors.forename: J Luis
authors.initials: JL
authors.lastname: Guerrero
authors.forename: Shengqiu
authors.initials: S
authors.lastname: He
authors.forename: Ajit P
authors.initials: AP
authors.lastname: Yoganathan
authors.forename: Gus J
authors.initials: GJ
authors.lastname: Vlahakes
mesh_terms: D006801:Humans; D008944:Mitral Valve Insufficiency / Q000473:pathology* / Q000503:physiopathology* / Q000601:surgery