Myocardial infarction in a canine model monitored by two-dimensional 31P chemical shift spectroscopic imaging.
We have developed a closed chest animal model that allows noninvasive monitoring of cardiac high energy phosphate metabolism before, during, and for at least 3 weeks after a myocardial infarction. Ten beagles underwent 2 h of coronary occlusion followed by 3 weeks of reperfusion. Myocardial high energy phosphates from 12-ml voxels were noninvasively tracked using 31P two-dimensional chemical shift imaging. Gadolinium enhanced 1H MRI identified the zone at risk, and radioactive microspheres assessed regional blood flow and partition coefficients. Occlusion of the left anterior descending coronary artery produced infarcts that were 13.7+/-8.8% (mean+/-SD) of the left ventricular volume. Rapid changes in the phosphocreatine and inorganic phosphate levels were observed during occlusion, whereas adenosine triphosphate levels decreased more slowly. All metabolites recovered to base-line levels 2 weeks after occluder release. Multiple inorganic phosphate peaks in the infarct voxel spectra indicated that more than one metabolically compromised tissue zone developed during occlusion and reperfusion. Microsphere data indicating three distinct blood flow zones during ischemia and reperfusion (<0.3, 0.3-0.75, and >0.75 ml/min/g) supported the grouping of pH values into three distinct metabolic distributions.
Farrall
A J
AJ
Lawson Research Institute, St. Joseph's Health Centre and Department of Medical Biophysics, The University of Western Ontario, London, Canada.
Thompson
R T
RT
Wisenberg
G
G
Campbell
C M
CM
Drost
D J
DJ
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D001783:Blood Flow Velocity; D003287:Contrast Media; D004195:Disease Models, Animal; D004285:Dogs; D005260:Female; D005500:Follow-Up Studies; D019786:Gadolinium DTPA; D006863:Hydrogen-Ion Concentration; D007089:Image Enhancement / Q000379:methods; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008863:Microspheres; D009203:Myocardial Infarction / Q000378:metabolism* / Q000503:physiopathology; D015425:Myocardial Reperfusion; D010725:Phosphocreatine / Q000031:analogs & derivatives / Q000378:metabolism; D010759:Phosphorus Isotopes
D003287:Contrast Media; D010759:Phosphorus Isotopes; D010725:Phosphocreatine; C025403:phosphocreatinine; D000255:Adenosine Triphosphate; D019786:Gadolinium DTPA