The Journal of Thoracic and Cardiovascular Surgery, Vol 86, 710-717, Copyright © 1983 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association
Persistent myocardial ischemia following chronic hyperoxia in conscious dogs
JF Borgia, SM Horvath and RA Sorich
Following acute occlusion of the proximal left anterior descending (LAD)
coronary artery, dogs were exposed continuously for 4 days in an
environmental chamber to either 21% or 40% oxygen. Regional transmural
myocardial blood flow was then determined by means of radioactive
microspheres (8 to 10 microD) while each animal breathed room air
(approximately equal to 21% oxygen). Blood flows in the anterolateral and
apical regions of the left ventricle in normoxic animals (n = 5) averaged
0.95 +/- 0.03 and 0.69 +/- 0.13 ml/min X gm-1, respectively. In hyperoxic
dogs (n = 5), blood flows in these regions were significantly lower,
averaging 0.71 +/- 0.07 and 0.28 +/- 0.08 ml/min X gm-1, respectively in
the anterolateral free wall, the greatest disparity in perfusion between
experimental groups occurred in the subendocardial layers, and macroscopic
evidence of necrosis was more widespread after hyperoxia.