Progressive change in collateral blood flow after coronary occlusion in conscious dogs

This study used a retrospective analysis of infarcted and salvaged tissue samples to determine the patterns of blood flow changes (radioactive microsphere technique) that occur within the area at risk during the first 24 h after coronary artery occlusion (CAO) in conscious dogs. With the triphenyl tetrazolium chloride (TTC) technique, individual samples were selected and included in either the infarcted (TTC-negative) or salvaged (TTC-positive) group. The infarcted and salvaged samples were paired according to blood flow levels of 0.1-0.2, 0.2-0.3, or 0.3-0.4 ml · min^-1 · g^-1 at either 5 min, 1h, 3h, or 6 h after CAO. In tissue samples that were salvaged, blood flow rose progressively, i.e., from 5 min to 1 h, from 1 to 3 h, from 3 to 6 h, and from 6 to 24 h. Blood flow to infarcted tissue rose only in the longest interval, from 6 to 24 h after CAO. When blood flow levels were <0.1 ml · min^-1 · g^-1, virtually all the samples were infarcted, whereas corresponding lesser amounts of infarction were observed with increasing blood flow levels after CAO. Thus, in the conscious dog, blood flow rises progressively to salvaged but not infarcted tissue within the area at risk. Except for myocardium with blood flow levels <0.1 ml · min^-1 · g^-1, the blood flow levels at any of the time points after CAO could not be used to predict necrosis.