Myocardial Infarction Alters Adaptation of the Tethered Mitral Valve.

Autor:	Dal-Bianco JP; Cardiac Ultrasound Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts; Leducq Transatlantic Mitral Network, Fondation Leducq, Paris, France., Aikawa E; Leducq Transatlantic Mitral Network, Fondation Leducq, Paris, France; Center for Excellence in Vascular Biology, Cardiovascular Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts., Bischoff J; Leducq Transatlantic Mitral Network, Fondation Leducq, Paris, France; Vascular Biology Program, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts; Department of Surgery, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts., Guerrero JL; Surgical Cardiovascular Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts., Hjortnaes J; Center for Excellence in Vascular Biology, Cardiovascular Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts., Beaudoin J; Cardiac Ultrasound Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts; Leducq Transatlantic Mitral Network, Fondation Leducq, Paris, France., Szymanski C; Cardiac Ultrasound Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts; Leducq Transatlantic Mitral Network, Fondation Leducq, Paris, France., Bartko PE; Cardiac Ultrasound Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts., Seybolt MM; Surgical Cardiovascular Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts., Handschumacher MD; Cardiac Ultrasound Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts., Sullivan S; Surgical Cardiovascular Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts., Garcia ML; Surgical Cardiovascular Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts., Mauskapf A; Surgical Cardiovascular Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts., Titus JS; Surgical Cardiovascular Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts., Wylie-Sears J; Vascular Biology Program, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts., Irvin WS; Center for Excellence in Vascular Biology, Cardiovascular Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts., Chaput M; Cardiac Ultrasound Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts; Leducq Transatlantic Mitral Network, Fondation Leducq, Paris, France., Messas E; Leducq Transatlantic Mitral Network, Fondation Leducq, Paris, France; Departments of Cardiology and Cardiovascular Surgery, Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, University Paris Descartes, INSERM Unit 633, Paris, France., Hagège AA; Leducq Transatlantic Mitral Network, Fondation Leducq, Paris, France; Departments of Cardiology and Cardiovascular Surgery, Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, University Paris Descartes, INSERM Unit 633, Paris, France., Carpentier A; Leducq Transatlantic Mitral Network, Fondation Leducq, Paris, France; Departments of Cardiology and Cardiovascular Surgery, Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, University Paris Descartes, INSERM Unit 633, Paris, France., Levine RA; Cardiac Ultrasound Laboratory, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts; Leducq Transatlantic Mitral Network, Fondation Leducq, Paris, France; Departments of Cardiology and Cardiovascular Surgery, Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges Pompidou, University Paris Descartes, INSERM Unit 633, Paris, France. Electronic address: rlevine@partners.org.
Jazyk:	angličtina
Zdroj:	Journal of the American College of Cardiology [J Am Coll Cardiol] 2016 Jan 26; Vol. 67 (3), pp. 275-87.
DOI:	10.1016/j.jacc.2015.10.092
Abstrakt:	Background: In patients with myocardial infarction (MI), leaflet tethering by displaced papillary muscles induces mitral regurgitation (MR), which doubles mortality. Mitral valves (MVs) are larger in such patients but fibrosis sets in counterproductively. The investigators previously reported that experimental tethering alone increases mitral valve area in association with endothelial-to-mesenchymal transition. Objectives: The aim of this study was to explore the clinically relevant situation of tethering and MI, testing the hypothesis that ischemic milieu modifies mitral valve adaptation. Methods: Twenty-three adult sheep were examined. Under cardiopulmonary bypass, the papillary muscle tips in 6 sheep were retracted apically to replicate tethering, short of producing MR (tethered alone). Papillary muscle retraction was combined with apical MI created by coronary ligation in another 6 sheep (tethered plus MI), and left ventricular remodeling was limited by external constraint in 5 additional sheep (left ventricular constraint). Six sham-operated sheep were control subjects. Diastolic mitral valve surface area was quantified by 3-dimensional echocardiography at baseline and after 58 ± 5 days, followed by histopathology and flow cytometry of excised leaflets. Results: Tethered plus MI leaflets were markedly thicker than tethered-alone valves and sham control subjects. Leaflet area also increased significantly. Endothelial-to-mesenchymal transition, detected as α-smooth muscle actin-positive endothelial cells, significantly exceeded that in tethered-alone and control valves. Transforming growth factor-β, matrix metalloproteinase expression, and cellular proliferation were markedly increased. Uniquely, tethering plus MI showed endothelial activation with vascular adhesion molecule expression, neovascularization, and cells positive for CD45, considered a hematopoietic cell marker. Tethered plus MI findings were comparable with external ventricular constraint. Conclusions: MI altered leaflet adaptation, including a profibrotic increase in valvular cell activation, CD45-positive cells, and matrix turnover. Understanding cellular and molecular mechanisms underlying leaflet adaptation and fibrosis could yield new therapeutic opportunities for reducing ischemic MR. (Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)
Databáze:	MEDLINE
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