A comprehensive hematologic study in calves with total artificial hearts

Thromboembolism and infection remain potential threats for long-term circulatory assist and replacement devices. The alteration of the hemostatic system and of blood cell functions caused by device implantation may predispose the recipient to these complications. Many sensitive coagulation assays and the technology of flow cytometry would be powerful tools for this investigation. The availability of such immunologic technologies for animal species other than humans has yet to be established. In a series of in vitro tests we found that the following assays, among others, are usable in calves: TAT, TxB2, platelet surface glycoprotein IIbIIIa, and membrane aminophospholipid. F1.2, D-dimer, beta TG, PF-4, and platelet surface expression of GMP-140 and receptors for fibronectin, thrombospondin, and vWF were not measurable. A sustained mild decrease in hematocrit levels in six calves with the Cleveland Clinic-Nimbus total artificial heart for 11-120 days was attributed to an increase in circulating blood volume, but not to red blood cell damage. Whole blood platelet aggregation was suppressed only for the first 3 post operative days, with decreased GPIIbIIIa expression. Polymorphonuclear phagocytosis, chemotaxis, and superoxide anion production were not altered. Device infection and thromboembolism occurred in one of 13 cases overall.