Vascular illness is characterized as “disease of the arteries and veins.” Blood vessels — arteries that carry oxygen-rich blood, and veins that return blood to the heart — are the circulatory system’s highways. The body cannot function properly without freely flowing blood. When plaque obstructs the flow of blood to any region of the body, conditions such as arterial hardening can generate “traffic jams.” Other vascular abnormalities may be congenital or develop as a result of pregnancy or another health problem.