title: Nuclear magnetic resonance analysis of acute myocardial infarction in dogs: the effects of transient coronary ischemia of varying duration and reperfusion on spin lattice relaxation times.
abstract: The purposes of this study were to evaluate the effects of acute myocardial ischemia with reperfusion on T1 (spin-lattice) nuclear magnetic resonance (NMR) relaxation times in a canine model and correlate these changes with bulk myocardial water content (%H2O). In 15 dogs the left anterior descending coronary artery was occluded for either 40 minutes (n = 5), 1 hour (n = 5), or 2 hours (n = 5). In 15 additional dogs, matched occlusion periods were followed by 3 hours of reperfusion. T1 of tissue from normal and ischemic myocardium was measured in vitro with a 2.5 kg NMR spectrometer. In the reperfusion animals, the 2-hour group showed significant increases in %H2O and T1 when the ischemic segment of myocardium was evaluated (both p less than 0.01). All but one animal in the 1-hour (reperfusion) group showed increases in both %H2O or T1 in the ischemic segment of myocardium when compared to control segments. The mean values from the ischemic myocardium in the 1-hour group were significantly higher than the values from the matched control segment for %H2O (p less than 0.05) and T1 (p less than 0.05). In the group undergoing 40 minutes of ischemia followed by 3 hours of reperfusion, neither %H2O nor T1 changed significantly. In the nonreperfused animals, neither T1 nor %H2O content increased significantly after 40 minutes. Significant increases were seen in the 1-hour (p less than 0.05) and 2-hour groups (without reperfusion) (p less than 0.01). In addition, the 2-hour occlusion followed by reperfusion animals had significantly greater T1 relaxation times and %H2O than control ischemic animals.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000818:Animals; D001157:Arterial Occlusive Diseases / Q000378:metabolism / Q000503:physiopathology; D001834:Body Water / Q000378:metabolism; D003327:Coronary Disease / Q000378:metabolism / Q000503:physiopathology / Q000628:therapy*; D004285:Dogs; D009682:Magnetic Resonance Spectroscopy; D009200:Myocardial Contraction; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000378:metabolism / Q000503:physiopathology; D009206:Myocardium / Q000378:metabolism; D010477:Perfusion; D013997:Time Factors