Medical Imaging International — MII February 2011
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Ultrasound Helps Clot-Busting Agents Dissolve Emboli

A new technique that combines the heat and energy of ultrasound with highly targeted delivery of clotbusting drugs appears to be an effective treatment for patients with acute massive pulmonary embolism (PE). The innovative treatment is called ultrasound-accelerated catheter-directed thrombolysis (developed by EKOS Corp. [Bothell, Washington;]). It adds a new dimension to catheter-directed thrombolysis (CDT), a procedure in which a high concentration of clot busting medication is delivered directly to the embolus over an extended period through an infusion catheter. In ultrasoundaccelerated CDT, the infusion catheter includes an element device that emits ultrasound energy in the therapeutic zone; the ultrasound works to make the clot more porous and more penetrable by the thrombolytic agent, thus lessening both the length of time of the infusion and the volume of thrombolytic drug applied.

The results of a study of 46 patients treated for massive PE over a 10-year period showed that ultrasound-accelerated CDT achieved complete thrombolysis in 100% of the patients treated compared to 67% patients receiving CDT without ultrasound. Peter Lin, MD, professor of surgery at the Baylor College of Medicine (Houston, TX, USA; presented his findings in November 2010 at the VEITHsymposium in New York (NY, USA).

Both the average dose of thrombolytic agent and the length of time for infusion were lower for patients receiving ultrasound-accelerated CDT. Furthermore, there were no hemorrhagic complications within this group compared to three incidents in the CDT group. All patients receiving ultrasound-accelerated CDT were treated with tissue plasminogen activator (tPA) as the thrombolytic agent. TPA was administered in 16 of the 21 patients undergoing CDT, with urokinase as the thrombolytic for the other 5.

Dr. Lin noted “while both CDT and ultrasound-accelerated therapy have remarkable therapeutic effects for this life-threatening condition, the EKOS device provides a significant added benefit of clearing most if not all the clot while using less drug.”

PE accounts for more than 300,000 deaths every year in the United States, and most of these are the result of acute massive PE and typically occur within one hour of presentation. For patients with hemodynamic instability from massive PE, systemic thrombolysis is considered to be the standard of care.