A technique to assess fibrinogen, platelet and red cell kinetics in calves with artificial hearts or circulatory assist devices.

1. Normal data for routine hematologic studies including fibrinogen, VIIIAHF, AT III, and circulating platelet aggregates are reported for Holstein calves. 2. Therapy with warfarin, ASA, and dipyridamole does not alter these parameters such as VIIIAHF, AT III, or circulating platelet aggregates. 3. 75SeM can be used as an in vivo label to study the fibrinogen, platelet, and red cell kinetics simultaneously in calves. 4. Decreased VIIIAHF levels and decreased platelet survival are the most sensitive parameters to estimate the activation of coagulation in the animals with circulatory assist devices. 5. The total heart animals seem to have a significant decrease in fibrinogen and VIIIAHF levels as compared to normal and left ventricular assist animals. 6. Despite the use of warfarin and antiplatelet drugs, decreased platelet survival occurred in both the total heart and the left ventricular assist animals. Fibrinogen half life with 75SeM must be interpreted with caution until corrections for pool size, reutilization, and nonpeptide binding have been considered.