Creation of fibrinogen-enhanced experimental blood clots to evaluate mechanical thrombectomy devices for treatment of acute stroke: an in vitro study.

Purpose: To explore if addition of fibrinogen to the most commonly used experimental blood clot (EBC) model would improve its mechanical properties and histologic structure.

Materials And Methods: Fresh blood from three swine was used to create four EBC types. The Gralla model of thrombin-induced barium-opaque EBC served as the control. In three other EBC types, 50 mg, 100 mg, and 200 mg of bovine fibrinogen were added. Evaluation of EBCs was done with three tests: manual elongation, injection through an 8-F catheter, and an opacity test. Thirty EBCs of each type were evaluated with each test. Histologic evaluation followed.

Results: The control EBCs had low tensile strength and broke at 165% elongation. However, they were elastic and returned to their original length after catheter injection. The EBCs with fibrinogen exhibited increased tensile strength with increasing fibrinogen doses and withstood elongation to 213% (P < .01). Their elasticity decreased with increased tensile strength, and they remained elongated after catheter injection (P < .01 for EBC with 100 mg and 200 mg fibrinogen). Histologic examination showed more thorough mixing of blood with barium and a significantly increased amount of fibrin after addition of fibrinogen.

Conclusions: Addition of fibrinogen to a Gralla EBC model changes its mechanical properties proportionately to the fibrinogen dose. Fibrinogen increases EBC tensile strength but decreases its elasticity. Fibrinogen also significantly increases the binding of blood cells with fibrin on histologic slides.