If the doctor detects a blood clot such as Deep Vein Thrombosis (DVT) or Pulmonary Embolus, one may be a candidate for state of the art catheter based therapy to treat the problem. During catheter-assisted thrombolysis treatment, a catheter is guided through blood vessels to the location of the blood clot, whether in the legs or in the lungs. The catheter will deliver special clot dissolving medicine called thrombolytics to help dissolve the clot. This new device, called EKOS, will also deliver simultaneous ultrasound energy to mechanically dislodge and loosen up the clot to enable lower and safer doses of the thrombolytic drugs to be used.