POTENTIAL CLINICAL IMPLICATIONS OF ABNORMAL MYOCARDIAL PERFUSION PATTERNS IMMEDIATELY AFTER REPERFUSION IN A CANINE MODEL - A MYOCARDIAL CONTRAST ECHOCARDIOGRAPHY STUDY

During myocardial infarction, lack of myocardial opacification after r eperfusion has been associated with poor or no recovery of function. W e have previously documented the presence of perfusion abnormalities a fter brief coronary occlusions without infarction and the absence of p erfusion abnormalities after prolonged occlusions with infarction. To characterize myocardial perfusion patterns immediately after reperfusi on, we studied 53 animals in two groups in a coronary occlusion-reperf usion model. Temporary occlusions (group 1, 15 minutes; group 2, 30 to 360 minutes) were performed, followed by reperfusion with and without dobutamine. Myocardial contrast echocardiography was performed with a ortic root injections of sonicated 5% serum human albumin (Albunex) du ring each intervention. Group 1 dogs showed no evidence of myocardial infarction. In group 2, 26 of 40 dogs had infarctions. After reperfusi on, no perfusion abnormalities were seen in 13 of 26 group 2 dogs with infarctions; perfusion abnormalities were identified after reperfusio n in 2 of 13 group 1 and in 8 of 14 group 2 dogs without infarctions. In animals subjected to prolonged ischemia, the absence of perfusion a bnormalities after reperfusion did not rule out the presence of necros is. Similarly, in animals without infarction subjected to ischemia, th e presence of a perfusion defect after reperfusion did not represent t he presence of necrosis but an abnormal microvascular reserve. These r esults suggest that early after reperfusion, assessment of perfusion b y myocardial contrast echocardiography has significant limitations in the evaluation of myocardial viability and salvage.