Incompetent valves

Deep vein (1), connecting vein (2), full-blown varicose vein (3)

Impaired function or loss of function of the valves in the superficial or deep veins. The valves no longer close properly and are not able to control the direction of flow. Incompetent (leaky) valves allow the blood to flow in the wrong direction under the force of gravity. Blood pools in the veins. The pressure in the vessels increases continuously until they dilate and ultimately develop varicose veins.