INVITRO INVESTIGATION OF THROMBOGENESIS IN ROTARY BLOOD PUMPS

Thrombus formation at sealing and stagnation areas remains a major pro blem in the development of rotary blood pumps. Until now, the complex phenomena could only be studied in vivo. In this study, an in vitro mo ck circulation previously used for hemolysis studies was adapted for t hrombosis evaluation. Blood was collected in the slaughterhouse with s trict avoidance of air contact and was heparinized (1.5 U heparin/ml b lood; activated coagulation time [ACT]: initially, 140-180 s; after co llection, 400-600 s). During the test, the ACT decreased gradually. Th e tests were stopped after 90 to 180 min at an ACT of 1.5 times the in itial value. Thrombus formation was observed at the same locations as observed in left-heart assist devices (sealing area, connecting bolts, and stagnant water areas at connectors). The thrombi were similar in shape, color, and histology to those found after 2 to 4 days in vivo. This test provides a valuable tool for evaluating thrombus formation i n prototypes and screening tests of different rotary pump designs.