A blockage of an artery or vein causes vascular occlusion. The blockage could occur as a result of: Compression or pressure against an artery by dermal filler substances injected into your skin. A blood clot in an artery or vein. Fatty plaque buildup in an artery or vein. Your arteries and veins carry blood from your heart to different parts of your body and back to your heart. A blockage prevents blood and oxygen from moving through your body’s pathways. This causes symptoms of the condition.