SVS on chronic venous insufficiency Chronic Venous Insufficiency (CVI) Chronic Venous Insufficiency 40 percent The Vein Clinic at University of Chicago Medicine Society of Vascular Surgery website Learn More The Vein Clinic at University of Chicago Medicine Venous Insufficiency chronic venous insufficiency Veins have valves Chronic venous insufficiency Chronic Venous Insufficiency chronic venous insufficiency 40% of the U.S. population Society of Vascular Surgeons chronic venous insufficiency up to 40 percent Venous Insufficiency Chronic Venous Insufficiency. Chronic Venous Insufficiency Society of Vascular Surgery Nearly 40% of Americans