Venous hemodynamics and microcirculation in chronic venous insufficiency

Venous hemodynamics provide our understanding for the development of chronic venous insufficiency and lower extremity venous ulcers. Venous blood flow and its anatomic conduits have now been well elucidated due to technological advancements both in imaging and flow dynamics. This has provided us with tools for effective clinical diagnosis, minimally invasive interventions, and ulcer treatment. More challenging, and with less progress, has been the elucidation of the cellular and biochemical pathophysiological mechanisms of ulcer development. Increased capillary hydrostatic pressures secondary to valvular insufficiency or venous obstruction are an extension of macrovascular hypertension. This in turn leads to increased capillary permeability, leakage of protein-rich fluid into the interstitial space causing elevated oncotic pressure within the interstitium leading to progressive edema formation when lymphatic drainage is overcome. Concomitantly, extensive cellular and cytokine inflammatory involvement induces a cascade of pathologic changes that, if unrelieved, causes permanent skin changes and ulcerations.