Arteries carry blood throughout the body, but veins are tasked with the more difficult, gravity-fighting job of transporting blood back up to the heart. Venous insufficiency is the main cause of leg vein diseases; meaning the valves in your leg veins aren’t working as efficiently as they should. If you’re experiencing leg vein issues, it’s a good idea to consult your doctor to determine just how serious the situation is and what the most appropriate treatment options are.