The effects of intravenous nitroglycerin on hemodynamics, coronary blood flow and morphologically and enzymatically estimated infarct size in conscious dogs.
Nitroglycerin (TNG) decreases ST-segment elevation accompanying myocardial ischemia, but its effect on morphometrically and enzymatically estimated infarct size (IS) has not been defined. Accordingly, coronary occlusion was produced in 92 conscious dogs; 65 survived for 24 hours. Thirty-three received TNG (200-300 microgram/min i.v. for 8 hours) and the results were compared with those in 32 untreated dogs. Coronary blood flow (CBF) was measured with tracer microspheres (141Ce, 85Sr and 95Nb) 5 minutes after occlusion before TNG, 20 minutes after TNG and again at 8 hours. Mean blood pressure decreased from 103 to 84 mm Hg with TNG, vs 99 to 94 mm Hg in controls (p > 0.02). Nitroglycerin increased CBF in the subendocardium of ischemic areas by 45% (0.09 to 0.13 ml/min/g). The dogs were sacrificed after 24 hours and IS was estimated morphometrically (25 +/- 1% vs 27 +/- 1% of left ventricular weight) and from myocardial CK depletion (23 +/- 1% vs 24 +/- 1%) were similar for the two groups. Thus, despite increased subendocardial CBF, prolonged i.v. TNG did not decrease infarct size, although a 15% difference would have been detected with this sample size. TNG may relieve coronary spasm but does not appear to be beneficial with sustained coronary occlusion.
D000818:Animals; D001157:Arterial Occlusive Diseases / Q000401:mortality; D001794:Blood Pressure; D003326:Coronary Circulation / Q000187:drug effects*; D003327:Coronary Disease / Q000401:mortality; D003402:Creatine Kinase / Q000097:blood; D004285:Dogs; D006339:Heart Rate; D006439:Hemodynamics / Q000187:drug effects*; D008297:Male; D009203:Myocardial Infarction / Q000503:physiopathology; D009206:Myocardium / Q000201:enzymology*; D005996:Nitroglycerin / Q000494:pharmacology*; D012039:Regional Blood Flow
D003402:Creatine Kinase; D005996:Nitroglycerin