Thrombolysis breaks up blood clots that are limiting or blocking blood flow through an artery or vein. An interventional radiologist, guided by fluoroscopy, inserts a catheter into a blood vessel, threads it to the clot and injects dye in order to see the clot. Then they can inject medicine to dissolve the clot, or they can use a machine to spray the clot with saline to break it up and suction the pieces out.