What is the difference between venous disease and arterial disease?

Peripheral arterial disease (PAD), in contrast to venous reflux disease, is caused by blockages in the arteries that prevent proper blood flow to the legs. Left untreated, PAD can lead to gangrene and loss of toes and is also an indicator for other serious blockages that can affect the heart and brain. PAD requires a totally different treatment than venous disease, a problem with blood flow from the legs due to diseased valves, not blockages.