The pulmonary embolism is mostly likely to have originated from the Deep veins of the leg response feedback. Pulmonary embolism occurs when a clump of material, most often a blood clot, gets wedged into artery in your lungs. These blood clots most commonly come from the deep veins of your legs. It is a blockage of an artery in the lungs by a substance that has moved from else where in the body through the bloodstream.