Coronary hemodynamics and subendocardial perfusion distal to stenoses.
We compared distal coronary hemodynamics and regional myocardial perfusion in anesthetized dogs in the presence of a single or two coronary artery stenoses in series. After application of either a single or two stenoses on the left anterior descending coronary artery, regional myocardial blood flow was measured with radioactive microspheres. Moderate degrees of single-vessel stenosis (no change in resting coronary blood flow but reduction in reactive hyperemic response of 70%) resulted in no significant change in regional myocardial perfusion at rest despite a pressure drop across the stenosis of 24 +/- 3 mm Hg. When two such stenoses were applied in series, there was a 91% decrease in reactive hyperemia, a significant reduction in resting diastolic coronary blood flow and a 51 +/- 7 mm Hg pressure drop across the two stenoses. Alone, each stenosis produced no change in regional myocardial perfusion; however, together the two stenoses resulted in a significant decrease in subendocardial blood flow and a redistribution of transmural perfusion within the ischemic zone favoring the subepicardium (endo/epi from 0.95 +/- 0.03 to 0.72 +/- 0.03). The results indicate that whereas resting subendocardial perfusion is not significantly affected by moderate degrees of a single coronary artery stenosis, multiple stenoses of the same severity may dramatically reduce subendocardial perfusion.
D000818:Animals; D001794:Blood Pressure; D003326:Coronary Circulation; D003327:Coronary Disease / Q000000981:diagnostic imaging / Q000503:physiopathology*; D003331:Coronary Vessels / Q000502:physiology; D004285:Dogs; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging; D006339:Heart Rate; D006439:Hemodynamics; D008297:Male; D008863:Microspheres; D009200:Myocardial Contraction; D011868:Radioisotopes; D011877:Radionuclide Imaging
D011868:Radioisotopes