The effectiveness of a coronary perfusion catheter was studied in an animal model of acute coronary occlusion. Systemic hemodynamic variables, regional myocardial blood flow (RMBF) in the subepicardium and subendocardium, and regional systolic function (systolic segmental shortening) of the area perfused by the circumflex coronary artery (CX) were measured in eight anesthetized dogs. After baseline measurements, the CX coronary artery was occluded with a silk snare and measurements were repeated after 5 minutes of ischemia (occlusion No. 1). The snare was released and 1 hour later the snare occlusion was repeated after placement of a perfusion catheter in the CX coronary artery. After 5 minutes, measurements were repeated (occlusion No. 2). To determine the long-term effectiveness of the catheter, hemodynamic variables and regional function measurements were then obtained every 15 minutes for a total of 60 minutes. During occlusion No. 1, RMBF decreased from 1.30 +/- 0.20 to 0.41 +/- 0.13 ml.min-1.gm-1 (p less than 0.01), and subendocardial RMBF decreased from 1.44 +/- .24 to 0.34 +/- 0.15 ml.min-1.gm-1 (p less than 0.01). After insertion of the perfusion catheter (occlusion No. 2), subepicardial RMBF was maintained at 0.97 +/- 0.16 and subendocardial RMBF was maintained at 0.78 +/- 0.13 ml.min-1.gm-1; during occlusion No. 2 subepicardial RMBF was greater (p less than 0.05) than occlusion No. 1 and was not different from baseline.(ABSTRACT TRUNCATED AT 250 WORDS)