Differential 18F-2-deoxyglucose uptake in viable dysfunctional myocardium with normal resting perfusion: evidence for chronic stunning in pigs.
BACKGROUND
Viable, chronically dysfunctional myocardium can have normal or reduced resting flow. We previously produced hibernating myocardium with reduced resting flow in pigs with a chronic stenosis and hypothesized that hibernation is preceded by chronic stunning with normal resting perfusion.


RESULTS
Pigs instrumented with a proximal left anterior descending coronary artery (LAD) stenosis were studied 1 or 2 months later in the closed-chest anesthetized state. Stenosis severity increased from 74+/-5% at 1 month to 83+/-6% at 2 months and was accompanied by anteroapical hypokinesis (wall motion score, 2.1+/-0.1 at 1 month and 1.5+/-0.3 at 2 months; normal=3). Resting perfusion was similar in normal and dysfunctional regions, but the deposition of 18F-2-deoxyglucose (FDG) varied. At 1 month, subendocardial FDG deposition by excised tissue counting was similar in each region (0. 034+/-0.006 mL. g-1. min-1 LAD region versus 0.032+/-0.004 mL. g-1. min-1 in normal regions, P=NS). At 2 months, subendocardial FDG deposition was increased (0.084+/-0.025 mL. g-1. min-1 LAD region versus 0.042+/-0.017 mL. g-1. min-1 in normal regions, P<0.05). Increases in FDG uptake were inversely related to LAD subendocardial flow reserve during adenosine (3.5+/-0.6 at 1 month versus 1.4+/-0.2 at 2 months, P<0.01).


CONCLUSIONS
These data indicate a progression of physiological adaptations in pigs with viable, chronically dysfunctional myocardium. As coronary flow reserve decreases, fasting FDG uptake increases. Flow at rest remains normal, consistent with "chronic stunning," and contrasts with reduced flow and increased FDG characteristic of hibernating myocardium in similarly instrumented pigs after 3 months. This temporal progression of adaptations supports the hypothesis of a transition from a physiological phenotype of stunning to hibernation.
Fallavollita
J A
JA
Department of Veterans Affairs, Western New York Health Care System, Department of Medicine, University at Buffalo School of Medicine and Biomedical Sciences, Buffalo, NY, USA. jaf7@buffalo.edu
Canty
J M
JM
D000818:Animals; D003326:Coronary Circulation / Q000502:physiology*; D003327:Coronary Disease / Q000503:physiopathology; D019788:Fluorodeoxyglucose F18; D006605:Hibernation / Q000502:physiology; D017682:Myocardial Stunning; D019275:Radiopharmaceuticals; D013552:Swine
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18