Intravascular ‘sonic lysis’ busts thrombi

A new ultrasound-based device can effectively treat peripheral arterial occlusion and deep vein thrombosis in record time, according to a multicenter study presented at the 2006 International Symposium on Endovascular Therapy in Miami Beach.

An untreated thrombus causing peripheral arterial occlusive disease or DVT may lead to foot or leg amputation, pulmonary embolism, and death. The new ultrasound-enhanced thrombolysis system could improve therapy by allowing physicians to begin heparin, alteplase, or urokinase infusion in half the time usually required for recanalization.

"This is a big step forward," said principal investigator Dr. Thomas McNamara, chief of vascular and interventional radiology at the University of California, Los Angeles Medical Center. "When you don't have overnight infusion, you almost never have bleeding."

The Lysus infusion system (EKOS Corporation, Bothell, WA) comprises a thin wire, beaded with up to 30 tiny ultrasound transducers, sheathed in a conventional catheter. Once it has been inserted in the affected area, the wire emits high-frequency, low-intensity waves as the catheter delivers the clot-busting drug, breaking thrombi's fibrin matrix apart. The manufacturer began testing with patients in Malmo, Sweden, in 1999 and secured FDA 510(k) market clearance in September 2004.

McNamara presented results from 13 U.S. institutions assessing the device. These centers have treated clots in 118 patients presenting with peripheral vascular occlusive disease. Available data on 62 patients with peripheral arterial disease and 33 patients with DVT show sonic lysis dissolved 87% and 70% of their clots, respectively, in less than 24 hours. Both patient groups also showed a 92% and 56% reduction in bleeding complications, respectively, compared with conventional treatment.

Conventional thrombolysis entails infusion at the site of the clot. Depending on thrombus size, it can take up to two days to complete. In addition, it is expensive and risky. Infusion times correlate heavily with potential limb- or life-threatening hemorrhage.

The new device enhances the ability to dissolve clots and may reduce complications, said Dr. James F. Benenati, director of the peripheral vascular lab at the Baptist Cardiac & Vascular Institute in Miami. Benenati's center is participating in the trial.

"It also may have the advantage of allowing the procedure to be done much more quickly, which will save physicians and hospitals time and lower the cost of the procedure," he said.

For more information from the Diagnostic Imaging archives:

Minimally invasive therapies break through in DVT

Revolution storms along in thrombolytic agents

Ultrasound shows promise for thrombosis treatment

Percutaneous ultrasonic technology tackles thrombus