White Thrombo - Embolism and Vascular

P LATELET thrombo-embolism is receiving recognition as an important condition. It is, as yet, poorly understood and cotssequent-ly difficult to diagnose. Lutz, Fulton and Akers’ have reported the presence of platelet thrombo-embolic conditions in hamsters after trauma, infection and malignant neoplasia and have related their results to various clinical manifest-atiotss and autopsy findings, characterized by plateletthrombi in practically all the peripheral blood vessels in 20 human cases. rfhe sigtsificatsce of intravascular agglutination has 1)eets discussed by one of us in a recent review. It is entirely logical that therapy with anticoagulants should be utilized in the treatment and prophylaxis of diseases associated with plateletthrombo-emholism. However, fundamental investigations pert-aitsitsg to the effectof these materials on platelet t-hrombo-embolism have beets limited for the most part to tests made in vitro on platelet adhesiveness.’ The testing of platelet adhesivetsess in vitro may not necessarily give a true picture of plateletagglutitsability as found in viyo. Thus the mamsy reports of no change, or even a decrease, in platelet adhesiveness during anticoagulant therapy,5’ are difficult to reconcile with the reported increase in platelet embolization under similar coisditions.’#{176} 13 The routine use of anticoagulants its pat-ietsts atsd its animals should be undertakets with a critical consideration of the possibility of detrimental changes its the st-ate of the small blood vessels and the characteristics of the blood flow. Evidence for such effects is presentits the literature. As a result of heparin administration, plateletemboli of leukocytic size w’ere seen in t-he living blood vessels of the cheek pouch of the hamster by Copley’#{176}and by Lutz, Fulton and Akers.mm Its hamsters treated with dicumarol for fourteems weeks, platelet t-hrombi and leukocytic coatings on the endothelium were observed and photographed by Lutz, Fult-oms and Akers.’3 Zucker’4 described the formation of plateletplugs as effective hemostatic agents in the mesoappendix of the rat treated with heparin and dicumarol. Jurgetss” reported that histamine and bacterial toxitss caused agglutination of platelets in the mesenteric veins of the rabbit-, even after anti-