The effect of hemodilution with fluorocarbon or dextran on regional myocardial flow and function during acute coronary stenosis in the pig.

: The effect of replacement of approximately 50% of the blood volume, in the presence of critical coronary stenosis, was investigated in anesthetized pigs. Two agents were used for replacement: 6% dextran 70 and Fluosol-DA, a fluorocarbon "blood substitute," capable of transporting oxygen by virtue of its high solubility. Critical coronary stenosis of 15-min duration was imposed on the circumflex coronary artery by means of a micrometer snare, before and after an exchange-transfusion with one of the above acellular agents, resulting in comparable reductions of myocardial blood flow (determined by microspheres) to the circumflex zone. In the ischemic zone, systolic wall-thickening (as determined by sonomicrometry) was reduced by 62 +/- 10% in the dextran-diluted pigs, but only by 33 +/- 7% in the Fluosol-diluted pigs (p less than .05). Estimated oxygen delivery-rate in this zone, during coronary constriction, was 6.2 and 7.5 ml min-1 100 g-1, respectively. Electron microscopic examination of the normally perfused zone of the heart showed no morphological change attributable to Fluosol. The findings suggest that, in the presence of critical coronary stenosis, hemodilution by Fluosol-DA can be tolerated, while similar hemodilution with dextran results in aggravation of myocardial hypoxia. In three instances, severe reactions were observed immediately following the administration of Fluosol. These were suggestive of complement-activation and were excluded from the analysis.