A Preparation to Study Simultaneous Arterial and Venous Thrombus Formation in Rabbits

Injury to an artery induces formation of a platelet-rich thrombus, while stasis or trauma to a vein induces a fibrin-rich thrombus. We have implemented preparations for evolving both platelet-rich and fibrin-rich thrombi simultaneously in rabbits for use to define the efficacy of novel antithrombotic agents. For platelet-rich thrombosis, a carotid artery and contralateral jugular vein were dissected and an arteriovenous shunt inserted distally to prevent cerebral infarction during thrombus formation. The shunted artery was then instrumented with a proximal Doppler probe for measuring flow velocity and a distal transluminal needle electrode. Electrical injury to the artery was induced by application of 250 microA of anodal current to the indwelling needle electrode. Thrombotic occlusion was consistently observed within 60 min, permitting measurements of the effects on the incidence and time of occlusion of antithrombotic agents administered over 2 h. For fibrin-rich thrombosis, an external jugular vein was dissected, including the distal bifurcation. One of the branches was catheterized and a copper wire with cotton threads attached was advanced through the catheter into the superior vena cava, allowing exposure of the threads to flowing blood. A 25- to 30-mg thrombus was formed within 2 h, permitting reliable measurements of effects on thrombus weight of antithrombotic agents administered during this interval. Implementing both arterial and venous thrombosis simultaneously did not change measurements compared with either method alone. This approach may facilitate recognition of differences in efficacy of selected agents against thrombi of diverse composition.