The direction is irrelevant. DVT compression pumps work by pumping the blood vessels near the surface and well below the surface of the skin. They are not intended to work on arteries. They increase blood flow, in one means, by decreasing back flow. That allows easier work from your arteries and heart and then increasing the blood flow.
Think of it as increasing the diameter of your exhaust pipe. Or adding a pump on your constricted exhaust to remove it quicker.