title: The influence of open-heart surgery during extreme hemodilution on the hemostatic mechanism in the dog.
abstract: 12 Labrador retriever dogs had mitral disc valves implanted during cardiopulmonary bypass (CPB) with extreme hemodilution, obtained with preoperative blood withdrawal, the use of blood-free priming fluid during perfusion, and retransfusion of autologous blood. Before operation, platelet adhesiveness as well as the reactivity of the intrinsic and extrinsic coagulation systems were markedly higher than in man. During CPB, the number of functioning platelets was very low, but increased after retransfusion, and were after 4 h twice as high as in 7 human patients who received aortic disc valves during CPB with extreme dilution. The extrinsic coagulation system also reacted much faster during and after CPB in the dogs, and heparin activity was rapidly neutralized and intrinsic coagulation normalized in them. Intravascular coagulation did not occur, and more hemolysis was induced in the dogs than in the patients. 3 of the dogs died from valve thrombosis within 24 h. The high reactivity of platelets and coagulation systems in the dog makes the canine model a very difficult one for experimental open-heart surgery because of a strong tendency to thrombosis.
mesh_terms: D000818:Animals; D001021:Aortic Valve / Q000601:surgery; D001780:Blood Coagulation Tests; D006348:Cardiac Surgical Procedures; D002315:Cardiopulmonary Bypass; D004285:Dogs; D006350:Heart Valve Prosthesis; D006438:Hemodilution; D006487:Hemostasis; D006801:Humans; D008943:Mitral Valve / Q000601:surgery; D010973:Platelet Adhesiveness; D010976:Platelet Count; D011183:Postoperative Complications; D013927:Thrombosis / Q000209:etiology