title: Platelet aggregation in partially obstructed vessels and its elimination with aspirin.
abstract: In 35 open chest anesthetized dogs coronary and aortic blood flow were measured with electromagnetic flowmeters while aortic and distal coronary blood pressure and an epicardial ECG were recorded. A fixed amount of stenosis (60-80%) was produced in the coronary artery by an externally applied plastic cylinder. In 24 of the 35 dogs the coronary blood flow showed cyclical reductions to near zero, with a sudden spontaneous return to near control levels. During reduced flow the epicardial ECG showed ST-segment depression suggestive of ischemia, and ventricular premature beats were often noted. Six animals died acutely during episodes of reduced flow. After 35 mg/kg of aspirin were given intravenously the cyclical reductions in coronary blood flow were abolished and the in vitro platelet aggregations were reduced from a control of 62.1 +/- 15 units (Born technique) to an average of 23.7 +/- 12 units. Histologic sections of the narrowed coronary artery obtained when coronary flow was reduced show an amorphous mass in the lumen which was thought to be a platelet aggregate. Perhaps a similar process of platelet aggregation occurs in the stenosed coronary arteries in man, producing acute coronary obstruction, ischemia, and sudden death.
mesh_terms: D000818:Animals; D001241:Aspirin / Q000627:therapeutic use*; D001783:Blood Flow Velocity; D001794:Blood Pressure / Q000187:drug effects; D003326:Coronary Circulation / Q000187:drug effects; D003327:Coronary Disease / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology; D003331:Coronary Vessels / Q000473:pathology / Q000503:physiopathology; D004211:Disseminated Intravascular Coagulation / Q000473:pathology / Q000503:physiopathology; D004285:Dogs; D004562:Electrocardiography; D005260:Female; D006493:Heparin / Q000627:therapeutic use; D008297:Male; D010974:Platelet Aggregation / Q000187:drug effects*
chemical_list: D006493:Heparin; D001241:Aspirin