Ranking the contributing risk factors in venous thrombosis in terms of therapeutic potential: Virchow's triad revisited.

Aim: Thromboemoblism is an attendant feature of a variety of pathological conditions. We reconsidered Virchow's pathogenetic triad of stasis, humoral factors and vascular wall pathologies in the light of platelet behavior in vivo.

Methods: Rat mesenteric microcirculation was examined by intravital microscopy. After isolated rat platelets had been injected i.v. into rats, their behavior in venules was examined under the following conditions: stasis from pressure, hemoconcentration from erythropoietin injections, or endothelial damage from tumor necrosis factor-alpha.

Results: In the endothelial damage group, platelets displayed transient adhesion and rolling, while some platelets exhibited stationary adhesion to venular endothelium. The stasis and hemoconcentration groups exhibited only a slight change in adhesive response.

Conclusion: Endothelial dysfunction appears to be the most important contributing factor in the development of venous thrombosis. As such, targeting this dysfunction is suggested for therapeutic intervention.