PAD is a common circulatory problem in which narrowing of the arteries causes reduced blood flow to the limbs. When one develops PAD, one’s extremities, usually the legs, don’t receive enough blood flow to keep up with demand. This causes leg pain during walking. Up to 12 million Americans have PAD and 50-75% of them are undiagnosed. Three out of four adults are not even familiar with PAD. It may be one of the deadliest diseases you’ve never heard of.