title: Magnetic resonance imaging assessment of cardiac function in a swine model of hibernating myocardium 3 months following bypass surgery.
abstract: Clinical studies demonstrate delayed recovery of hibernating myocardium (HM) following coronary artery bypass graft (CABG) surgery. Cardiac magnetic resonance (CMR) imaging is effective in identifying HM in clinical settings. Our animal model of HM shows partial but incomplete functional recovery 1 month following CABG using echocardiography. This study uses CMR imaging to determine completeness of recovery 3 months post-CABG.
  
  
  
  Swine (N = 12) underwent left anterior descending artery (LAD) 1.5-cm constrictor placement creating a territory of HM over 12 weeks. CMR at 12 weeks confirmed hibernation without infarction (N = 12). Off-pump left internal thoracic artery (LITA) to the LAD was performed in 9 animals. Three animals were killed as HM controls. CMR imaging was repeated in revascularized animals before death at 1 (n = 4) or 3 months (n = 5). CMR imaging was performed at baseline and with dobutamine infusion (5 μg/kg/min).
  
  
  
  Twelve weeks after constrictor placement, CMR imaging confirmed viability in LAD region and LAD stenosis in all animals. In HM, wall thickening is reduced at baseline but with contractile reserve present during dobutamine infusion. Following revascularization, CMR imaging confirmed patent LITA graft (n = 9). Analysis of baseline regional function shows incomplete recovery of HM following CABG, with reduced contractile reserve at both 1 and 3 months post-CABG.
  
  
  
  CMR imaging provides accurate spatial resolution of regional contractile function and confirms the presence of HM at 12 weeks following instrumentation of the LAD. Three months following CABG, partial recovery of HM with contractile reserve is present in the single LAD territory.
authors.affiliation: Department of Surgery, University of Minnesota, Minneapolis, Minn. Electronic address: stone337@umn.edu.
authors.forename: Laura L
authors.initials: LL
authors.lastname: Hocum Stone
authors.affiliation: Department of Surgery, University of Minnesota, Minneapolis, Minn.
authors.forename: Cory
authors.initials: C
authors.lastname: Swingen
authors.affiliation: Department of Surgery, University of Minnesota, Minneapolis, Minn.
authors.forename: Christopher
authors.initials: C
authors.lastname: Holley
authors.affiliation: Department of Surgery, University of Minnesota, Minneapolis, Minn.
authors.forename: Christin
authors.initials: C
authors.lastname: Wright
authors.affiliation: Department of Surgery, University of Minnesota, Minneapolis, Minn.
authors.forename: Erin
authors.initials: E
authors.lastname: Chappuis
authors.affiliation: Department of Surgery, University of Minnesota, Minneapolis, Minn.
authors.forename: Herbert B
authors.initials: HB
authors.lastname: Ward
authors.affiliation: Cardiology Division, Minneapolis VA Medical Center, Minneapolis, Minn.
authors.forename: Edward O
authors.initials: EO
authors.lastname: McFalls
authors.affiliation: Department of Surgery, University of Minnesota, Minneapolis, Minn.
authors.forename: Rosemary F
authors.initials: RF
authors.lastname: Kelly
mesh_terms: D000818:Animals; D001026:Coronary Artery Bypass / Q000379:methods*; D003324:Coronary Artery Disease / Q000601:surgery; D003326:Coronary Circulation / Q000502:physiology*; D004195:Disease Models, Animal; D005500:Follow-Up Studies; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D009200:Myocardial Contraction / Q000502:physiology*; D017682:Myocardial Stunning / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D011184:Postoperative Period; D020127:Recovery of Function; D013552:Swine; D013997:Time Factors
keywords: cardiac MRI; hibernating myocardium; ischemia