Thrombolytic effects of intracoronary streptokinase on canine coronary artery thrombosis

Abstract

The thrombolytic and hemodynamic properties of intracoronary streptokinase (SK) application were studied in an in-vivo canine model with left circumflex coronary artery thrombosis, initiated by electrical stimulation (150 microA, DC for 6 h) of the artery's intima via an implanted silver wire. In pentobarbital-anesthetized, open-chest dogs acute myocardial ischemia was determined by a dehydrogenase-dependent staining of the coronary artery perfusion area. Thrombus weight was determined post-mortem. Saline-treated control animals developed coronary thrombosis after 3.1 +/- 0.4 h of stimulation. Thrombus weight was 64 +/- 3.1 mg. Acute infarct volume was 32 +/- 3.1% of total left ventricle, and 53 +/- 6.2% of the coronary artery risk region for infarction. At occlusive thrombosis, blood pressure, ventricular pressure and the LV dP/dtmax fell significantly, whereas heart rate and the end-diastolic filling pressure increased. Severe ST-segment elevation and loss of R wave voltage indicated myocardial ischemia. At 20 min into thrombotic vessel occlusion, 2,000 IU/min SK were infused by way of a Sones-catheter advanced to the thrombus. Coronary thrombosis consistently lysed after 12 +/- 0.7 min of SK infusion, and coronary blood flow as well as hemodynamics were restored. Only minor acute infarction was found indicating viability of ischemic jeopardized myocardium. In another group, the continuous SK-infusion (20 IU/kg/min) concomitant with electrical vessel stimulation prevented coronary thrombosis and acute ischemia, and no significant hemodynamic alterations were noted. These results indicate that intracoronary SK-infusion can lyse acute thrombosis as sequel of electrical stimulation. This prevents development of acute myocardial infarction. Continuous SK-infusion can completely prevent coronary thrombosis in response to intimal injury.