title: Novel pathogenetic mechanisms and structural adaptations in ischemic mitral regurgitation.
abstract: Ischemic mitral regurgitation (MR) is a common complication of myocardial infarction thought to result from leaflet tethering caused by displacement of the papillary muscles that occurs as the left ventricle remodels. The author explores the possibility that left atrial remodeling may also play a role in the pathogenesis of ischemic MR, through a novel mechanism: atriogenic leaflet tethering. When ischemic MR is hemodynamically significant, the left ventricle compensates by dilating to preserve forward output using the Starling mechanism. Left ventricular dilatation, however, worsens MR by increasing the mitral valve regurgitant orifice, leading to a vicious cycle in which MR begets more MR. The author proposes that several structural adaptations play a role in reducing ischemic MR. In contrast to the compensatory effects of left ventricular enlargement, these may reduce, rather than increase, its severity. The suggested adaptations involve the mitral valve leaflets, the papillary muscles, the mitral annulus, and the left ventricular false tendons. This review describes the potential role each may play in reducing ischemic MR. Therapies that exploit these adaptations are also discussed.
authors: Icahn School of Medicine at Mount Sinai, New York, New York. Electronic address: jeffrey.silbiger@mssm.edu.
authors: Jeffrey J
authors: JJ
authors: Silbiger
mesh_terms: D000222:Adaptation, Physiological; D064752:Atrial Remodeling / Q000502:physiology*; D004108:Dilatation, Pathologic; D006352:Heart Ventricles / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D008943:Mitral Valve / Q000473:pathology / Q000503:physiopathology; D008944:Mitral Valve Insufficiency / Q000000981:diagnostic imaging / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D009203:Myocardial Infarction / Q000150:complications; D010210:Papillary Muscles; D014463:Ultrasonography; D016277:Ventricular Function, Left / Q000502:physiology
keywords: Atriogenic leaflet tethering; EMT; Echocardiography; Epithelial (endothelial)–mesenchymal transition; Epithelial-mesenchymal transition; Ischemic mitral regurgitation; LV; Left ventricular; Left ventricular false tendons; MR; Mitral annulus; Mitral regurgitation; PM; Papillary muscle; Papillary muscles; VVL; Ventricular valvular loop; Ventricular-valvular continuity