Coronary and Microvascular Thrombolysis with Guided Diagnostic Ultrasound and Microbubbles in Acute ST Segment Elevation Myocardial Infarction

摘要

During a microbubble infusion, guided high mechanical index impulses from a diagnostic two dimensional transducer improve microvascular recanalization in acute ST segment elevation myocardial infarction (STEMI). The purpose of this study was to further elucidate the mechanism of improved microvascular flow in normal and hyperlipidemic, atherosclerotic pigs. In 14 otherwise normal pigs, an acute left anterior descending thrombotic coronary occlusion was created. Pigs subsequently received aspirin, heparin and ½ dose fibrinolytic agent (Tenecteplase or tissue plasminogen activator), followed by randomization to either no additional treatment (Group I), or a continuous infusion of non-targeted microbubbles and guided high mechanical index impulses from a three dimensional transducer (3D/mechanical index; Group II). Epicardial recanalization rates, ST segment resolution, microsphere-derived myocardial blood flow (MBF), and ultimate infarct size using myocardial contrast echocardiography were compared. The same coronary thrombosis was created in a set of 12 hypercholesterolemic pigs who were then treated with the same pharmacologic and ultrasound regimen (Group III; n=6) or the pharmacologic regimen alone (Group IV; n=6). Epicardial recanalization rates in Group I and II pigs were the same (29%), however, peri-infarct MBF and ultimate infarct size improved following treatment in Group II pigs (p <0.01 versus Group I). In Group III pigs, epicardial recanalization was 100% (compared to 50% in Group IV), and there were significant reductions in ultimate infarct size (p=0.02 compared to Group IV). We conclude that guided high mechanical index impulses from a diagnostic transducer and non-targeted microbubbles improve peri-infarct microvascular flow in acute STEMI, even when epicardial recanalization does not occur.