Blood is transported throughout the body through both arteries and veins, but a significant difference between the two is the presence of valves in veins. Some people develop chronic venous disease (CVD), which initially causes higher venous blood pressure and vein dilation, resulting in weakened vein valves. What do you predict would happen as the valve damage progresses?

Blood would leak backwards through the damaged valves due to gravity, causing lower leg swelling.
Veins would thicken constrict, causing a restriction in blood flow, and leading to arterial leakage.
Veins would carry a both oxygenated and deoxygenated blood away from the legs, causing oxygen deficiency.
Blood flow would increase through the veins, since the blood would not be impeded by valves.

Blood would leak backwards through the damaged valves due to gravity, causing lower leg swelling.