Varicose veins, along with edema, skin changes, dermatitis and venous ulcers, are typically caused by incompetent valves in the greater saphenous vein (GSV). Healthy valves in the veins stop the backflow of blood between heartbeats. When these valves are damaged, the blood leaks and pools in the legs and feet. This venous insufficiency puts significant pressure on the veins, causing them to bulge into varicose veins or resulting in the other symptoms associated with venous reflux disease.