A common complaint that affects many people is varicose veins, which are caused by the superficial veins of the leg not working as well as they could. However, DVT is different from varicose veins and is a more serious problem. There are two systems of veins in your legs: deep veins, which are the most important and carry most of the blood back to your heart, and superficial veins just under the skin, which are less important and transport blood from the skin and from the tissue just below the skin. Varicose veins are affected superficial veins and can lead to chronic venous insufficiency, i.e. venous obstruction of the blood flow in the leg. As a result of this blood flow obstruction, the risk of a thrombosis forming can be increased.