Magnetic resonance imaging assessment of cardiac function in a swine model of hibernating myocardium 3 months following bypass surgery

Abstract Objective 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 fun...

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Bibliographic Details
Published in:The Journal of thoracic and cardiovascular surgery 2017-03, Vol.153 (3), p.582-590
Main Authors: Hocum Stone, Laura L., PhD, Swingen, Cory, PhD, Holley, Christopher, MD, Wright, Christin, BA, Chappuis, Erin, Ward, Herbert B., MD, McFalls, Edward O., MD, PhD, Kelly, Rosemary F., MD
Format: Article
Language:English
Subjects:
Animals
cardiac MRI
Cardiothoracic Surgery
Coronary Artery Bypass - methods
Coronary Artery Disease - surgery
Coronary Circulation - physiology
Disease Models, Animal
Follow-Up Studies
hibernating myocardium
ischemia
Magnetic Resonance Imaging, Cine - methods
Myocardial Contraction - physiology
Myocardial Stunning - diagnosis
Myocardial Stunning - etiology
Myocardial Stunning - physiopathology
Postoperative Period
Recovery of Function
Swine
Time Factors
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Summary:Abstract Objective 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. Methods 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). Results 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. Conclusions 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.
ISSN:0022-5223
1097-685X
DOI:10.1016/j.jtcvs.2016.10.089