title: Is avoidance of air contact necessary for the in vitro evaluation of thrombogenicity in mechanical circulatory assist devices?
abstract: An effective in vitro protocol for the investigation of thrombogenicity can provide many advantages in the development of mechanical circulatory assist devices. Strict avoidance of air contact with blood recently was proposed for reliable in vitro evaluation. This study was performed to confirm the necessity of avoidance of air contact for the in vitro test of thrombogenicity in a rotary pump. Two sets of mock circuits with the same rotary blood pumps, reservoirs, and connecting tubes were made. In one system, blood came in contact with air while the other did not. The test blood was heparinized at the dose of 1 IU per 1 ml of blood. The tests were terminated at an activated coagulation time of 1.5 times the control value. The levels of hematocrit, platelet, factors VIII and XII, fibrinogen, thromboxane B2, and plasma-free hemoglobin were measured during the procedures. After the experiments, the thrombi formed were observed, measured, and compared with those formed in in vivo circumstances. The tests were repeated 12 times. There were no statistically significant differences between the 2 groups in hematologic parameters and the amounts of thrombi formed. The thrombi observed in both groups showed the same pathologic findings as those formed in vivo with the exception of intermittent multiple air bubbles found in thrombi of the air-contact group. In conclusion, the effect of air contact in the in vitro investigation of thrombogenicity was negligible while the proposed in vitro test models of thrombogenesis in the mechanical circulatory assist device proved to be reliable.
authors.affiliation: Department of Thoracic and Cardiovascular Surgery, Clinical Research Institute, Seoul National University Hospital, Heart Research Center, Seoul National University College of Medicine, Seoul, Korea. wongon@plaza.snu.ac.kr
authors.forename: W G
authors.initials: WG
authors.lastname: Kim
authors.forename: M H
authors.initials: MH
authors.lastname: Na
authors.forename: J H
authors.initials: JH
authors.lastname: Kim
mesh_terms: D000388:Air; D000925:Anticoagulants / Q000008:administration & dosage / Q000097:blood; D001243:Assisted Circulation / Q000295:instrumentation*; D001769:Blood; D001777:Blood Coagulation / Q000502:physiology; D004867:Equipment Design; D005169:Factor VIII / Q000032:analysis; D005174:Factor XII / Q000032:analysis; D005340:Fibrinogen / Q000032:analysis; D006400:Hematocrit; D006454:Hemoglobins / Q000032:analysis; D006493:Heparin / Q000008:administration & dosage / Q000097:blood; D006801:Humans; D010976:Platelet Count; D015203:Reproducibility of Results; D013927:Thrombosis / Q000209:etiology*; D013929:Thromboxane B2 / Q000097:blood; D014914:Whole Blood Coagulation Time
chemical_list: D000925:Anticoagulants; D006454:Hemoglobins; D013929:Thromboxane B2; D005169:Factor VIII; D005174:Factor XII; D005340:Fibrinogen; D006493:Heparin