The effect of synchronized coronary venous retroperfusion of arterial blood on cardiac function after experimental coronary occlusion was examined by two-dimensional echocardiography. In 18 closed chest anesthetized dogs, the proximal left anterior descending coronary artery was occluded for 6 hours with an intracoronary balloon catheter. Eight of these animals served as untreated controls. Ten were treated with synchronized retroperfusion initiated 30 minutes after occlusion, and treatment was interrupted for 5 minutes at 1 hour after occlusion for study of the rapidity of retroperfusion response. Quantitative echographic analysis yielded global ejection fraction and regional indexes of contraction in a low left ventricular short-axis section, including segmental systolic area change, systolic wall thickening and end-diastolic wall thickness. At 6 hours after occlusion, ejection fraction had decreased from 50.7 +/- 4.9% to 28.1 +/- 7.7% (mean +/- standard deviation) in control dogs, but was significantly (p less than 0.01) less depressed in treated dogs (from 55.9 +/- 5.2 to 41.8 +/- 9.3%). The ischemic zone fractional area change at 30 minutes of occlusion exhibited a marked depression in both groups, after which the dysfunction persisted in the control dogs, but was largely reversed with retroperfusion from 6.0 +/- 6.5 to 35.9 +/- 15.9% at 6 hours of occlusion (p less than 0.01). Brief interruption of retroperfusion 1 hour after occlusion reduced ischemic zone fractional area change from 33.0 +/- 14.9 to 12.2 +/- 9.5% (p less than 0.01). This depression was promptly reversed to 33.6 +/- 12.2% when retroperfusion was resumed. Segmental wall thickening followed a similar trend.(ABSTRACT TRUNCATED AT 250 WORDS)