Why the study?
Do nitroglycerin and propranolol alter regional myocardial blood flow distribution during acute myocardial ischemia in a canine model?
Do nitroglycerin and propranolol alter regional myocardial blood flow distribution during acute myocardial ischemia in a canine model?
In a canine model of acute myocardial ischemia, nitroglycerin and propranolol improved the endocardial to epicardial blood flow ratio in both ischemic and nonischemic areas.
Hypothesis-generating for transmural flow redistribution in ischemia; leaves open translation to human acute coronary syndromes.
Radioactive microspheres were used to estimate the changes in regional myocardial blood flow occurring during acute myocardial ischemia. Carbonized 15-µ spheres were injected into the left atrium of 28 open-chest dogs and the radioactivity of selected areas determined after sacrifice. Acute occlusion of the left circumflex coronary artery produced a significant diminution in the proportion of microspheres reaching the circumflex area. In addition, there was a disproportionate decrease in endocardial radioactivity in the ischemic area (endocardial/epicardial radioactivity ratio falling from 1.17 to 0.76, P < 0.001) but not in the nonischemic area. Both nitroglycerin (0.4 mg) and propranolol (1 mg/kg) failed to cause a significant change in the ratio of circumflex to descendens radioactivity during ischemia. They did, however, cause a significant increase in the ratio of endocardial to epicardial radioactivity in both ischemic and nonischemic areas.
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Becker et al. (1971) studied this question.
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