Studies in intravascular coagulation. I. Coagulation changes in isolated venous segments.

Significant advances have recently been made in our understanding of the biochemistry of blood coagulation. Most of this work has, of necessity, been performed on blood in vitro. In sivo studies have been hampered by the difficulty of producing clots and thromboses in animals under controlled conditions and by the fact that, unlike the hemorrhagic diseases, there are no known clinical states in which a specific defect responsible for hypercoagulability of the blood has been demonstrated. We had been impressed by the repeated references in the literature to the effect that a stationary column of blood in a vein included between two carefully applied ligatures will remain liquid for weeks (1, 2). The experiments referred to were carried out more than seventy-five years ago and review of the original data did not indicate clearly whether or not clotting had occurred in these segments (3, 4). It occurred to us that a study of what did happen to the clotting mechanism in isolated endothelial-lined segments might provide a bridge between our knowledge of test tube coagulation and of the clotting process as it evolves in a more physiologic environment. Some of the results obtained are herewith presented.