The effects of oral pretreatment with
mioflazine (2.5 mg X kg-1) on regional myocardial reflow,
infarct size reduction and hemodynamic recovery were studied in 24 anesthetized open-chest dogs undergoing 90 minutes of acute left anterior descending coronary artery (LAD) occlusion followed by 150 minutes of reperfusion. Regional myocardial blood flow was measured with tracer
microspheres, and
infarct size was determined by triphenyl tetrazolium
chloride staining. Pretreatment with
mioflazine resulted in a reduced diastolic aortic pressure (p less than 0.05) and an elevated cardiac output and LV dpdt max (p less than 0.05). These effects persisted throughout the experiment. In control animals (n = 12) a hyperemic reflow response was found in the perfusion area of the LAD during the first minutes of reperfusion. After 150 min of reperfusion, however, the viable myocardium of the LAD area became underperfused, and almost no reflow was found in the infarcted zones. In the animals pretreated with
mioflazine (n = 12) the hyperemic response persisted throughout the reperfusion phase and the
no-reflow phenomenon was prevented.
Infarct size (expressed as percentage of perfusion area) tended to be smaller in this group: 23.7 +/- 12.4% versus 33.7 +/- 19.2% (p greater than 0.05). Left atrial pressure increased during LAD occlusion in both groups but normalized completely in the
drug-pretreated animals (p less than 0.05). It is concluded that pretreatment with
mioflazine prevents the
no-reflow phenomenon after reperfusion of an evolving
infarction, tends to reduce
infarct size and improves hemodynamic recovery.