Three new pharmacomechanical thrombolysis techniques presented on at the SIR annual meeting provide highly effective DVT treatment with less risk, medication, and cost than the current catheter-directed thrombolysis technique, which uses drugs alone.
The new techniques combine the use of clot busting drugs with clot macerating devices to break up the clot in the leg. By using pulsing spray or a macerating motion, the devices mechanically break up the clot, allowing the clot dissolving drugs to work much quicker.
Dr Suresh Vedantham of Washington University, St. Louis, said the techniques allow interventional radiologists to break up the clot in one day, often in a single session. "This has the potential to become a standard outpatient treatment and could really change the way DVT patients are treated," Vedantham said.
Removing these clots is important because approximately 50% of the time, untreated clots will cause post-thrombotic syndrome, a condition characterised by chronic leg pain and swelling. Post-thrombotic syndrome is caused by a combination of vein valve damage and blocked blood flow in the vein from residual thrombus (clot).
In a media presentation, Vedantham discussed the Power Pulse Spray, Trellis and Helix studies. In both the Power Pulse Spray and Trellis studies, over 80% of patients were treated in a single session, without the need for overnight infusion. In the Helix study, which compared the pharmacomechanical technique to catheter-directed thrombolysis (CDT), the treatment time was also significantly shorter than CDT, and there was a trend towards fewer bleeding events.
The power pulse spray injects a diluted clot-dissolving drug throughout the clot at high force. This helps break up the clot and deliver the drug to more surface area throughout the clot. After waiting approximately half-an- hour to allow the clot to partially dissolve, powerful saline jets create a vacuum that draws the clot (thrombus) into the catheter where it is removed from the body.
The Trellis-8 Infusion System is positioned at the site of the clot and a balloon is inflated on both sides of the clot to prevent pieces from travelling to other parts of the body and to isolate the treatment zone, so that there is less chance the infused drug will cause bleeding. Then a "wire filament" is fed through the clot. The wire begins to whip around, chewing the clot into pieces that are pulled/aspirated into the catheter and removed from the body. The Trellis was recently FDA approved as a drug infusion catheter for vascular clots.
The Helix Clot Buster Thrombectomy Device is a mechanical thrombectomy catheter that macerates the clot. A drive shaft, extending the length of the catheter, rotates an encapsulated impeller housed at the distal end of the device. This miniature impeller creates a re-circulating vortex that homogenizes the thrombus. The Helix is approved for dialysis graft clots and is being investigated for DVT.
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