This study examines the effects of brief periods of ischemia on average and cardiac cycle-dependent variation of regional ultrasonic backscatter paralleled with changes in regional myocardial contraction, and to what extent these changes could be reversed by synchronized coronary venous retroperfusion. In five closed-chest dogs, the left anterior descending coronary artery was occluded on four occasions for a 2-minute period and retroperfusion was applied randomly to two of the coronary occlusions. Complete functional recovery was allowed between the occlusions. Two-dimensional echocardiographic images were obtained before and at the peak of the 2-minute occlusion period. Regional myocardial contraction as measured by fractional area change and systolic wall thickening during untreated occlusions decreased from 33.9 +/- 14.0% to -0.15 +/- 6.2%, and from 22.0 +/- 1.8% to -17.9 +/- 2.2%, whereas during retroperfusion-treated occlusions it changed from 37.4 +/- 8.5% to only 23.4 +/- 11.2% (p less than 0.005 versus baseline), and from 24.1 +/- 2.8% to only 12.7 +/- 2.0% (p less than 0.005 versus baseline), corresponding to a preservation of 62% and 52% of baseline regional contraction, respectively. Average regional gray level (arbitrary units) during untreated coronary occlusions exhibited a significant increase in the ischemic regions, from 5.6 +/- 2.7 at baseline to 11.5 +/- 4.4 during occlusion (p less than 0.005); during retroperfusion-treated occlusions, average gray level increased from 4.7 +/- 3.6 to only 6.3 +/- 3.6 (NS). Untreated coronary artery occlusions resulted in a systolic increase in gray level in the ischemic region, followed by a diastolic decrease.(ABSTRACT TRUNCATED AT 250 WORDS)