Temporal changes in function and regional glucose uptake within stunned porcine myocardium.
This study compared the effects of porcine myocardial stunning on the uptake of [18F]-fluorodeoxyglucose (FDG) at 24 hr and 7 days after reperfusion. Prior studies in animals subjected to severe myocardial ischemia have shown a sustained increase in FDG uptake relative to perfusion (FDG/MBF). The time course of recovery of FDG/MBF relative to function poststunning, however, has not been well characterized.


METHODS
Stunning was induced in eight swine by partially occluding the LAD artery for 20 min. At 1 and 7 days postreperfusion, function was assessed by two-dimensional echocardiography and PET studies were obtained with FDG and either 15O-water or 13N-ammonia. Blood flow by microspheres was determined at baseline, during ischemia and after stunning. Myocardial uptake of FDG relative to blood flow on matching images (FDG/MBF) was calculated for all ROIs and expressed as a ratio of LAD to non-LAD areas.


RESULTS
After stunning, left ventricular ejection fraction (LVEF) increased from 42% +/- 10% on Day 1 to 52% +/- 6% on Day 7 (p < 0.05). At Day 1, myocardial blood flow was 0.60 +/- 0.10 ml/min/g in LAD and 0.67 +/- 0.16 in non-LAD regions and neither differed at Day 7. The magnitude of FDG/MBF in the LAD region when normalized to the non-LAD region was 1.29 +/- 0.16 on Day 1 and 1.09 +/- 0.08 on Day 7 (p < 0.05) and was inversely proportional to global measures of LVEF (r2 = 0.61; p < 0.005).


CONCLUSIONS
The severity of postischemic LV dysfunction at 1 and 7 days after stunning correlates with the degree of enhanced regional glucose uptake as estimated by PET. Both normalize within 7 days, suggesting that metabolic and functional abnormalities within completely reperfused myocardium recover in parallel.
McFalls
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EO
Cardiovascular Division, VA Medical Center, Minneapolis, Minnesota, USA.
Baldwin
D
D
Marx
D
D
Fashingbauer
P
P
Ward
H
H
D000818:Animals; D003326:Coronary Circulation; D003847:Deoxyglucose / Q000031:analogs & derivatives; D005462:Fluorine Radioisotopes; D019788:Fluorodeoxyglucose F18; D005947:Glucose / Q000378:metabolism*; D015425:Myocardial Reperfusion; D017682:Myocardial Stunning / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000503:physiopathology; D009206:Myocardium / Q000378:metabolism*; D013318:Stroke Volume; D013552:Swine; D013997:Time Factors; D014055:Tomography, Emission-Computed
D005462:Fluorine Radioisotopes; D019788:Fluorodeoxyglucose F18; D003847:Deoxyglucose; D005947:Glucose