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Macerating Device for Deep Vein Thrombosis Reduces Time, Risks for Thrombolysis: Presented at SIR

By Paula Moyer

NEW ORLEANS, LA -- April 4, 2005 -- A new generation of thrombosis-macerating devices may allow surgeons to treat deep vein thrombosis in one session, compared to the traditional methods, according to findings presented here April 1^st at the 30^th annual meeting of the Society of Interventional Radiology.

"Now we can remove blood clots in a single session versus the conventional method of thrombolysis, which consists of a 2-day infusion," said Suresh Vedentham, MD, assistant professor of radiology and surgery, Washington University in St. Louis, Missouri, United States, in reference to a study of one of the devices.

Dr. Vedentham said that many doctors have been reluctant to use thrombolytic therapies because of the long duration of treatment. Pharmacomechanical catheter-directed thrombolysis with early stent placement, also known as mechanical thrombectomy, provides a faster option for these patients, he said.

"The treatment allows the thrombolytic to work faster, typically [in] less than a day," he said. "Some patients just take the treatment and leave. It results in less bleeding complications, so that treatment is safer, faster and more convenient, as well as somewhat more effective."

He and his co-investigators evaluated the feasibility of mechanical thrombectomy with the Helix Clot Buster Thrombectomy Device, manufactured by ev3, Inc. They compared its initial effectiveness to that of conventional treatment, consisting of anticoagulants and stent placement following clot removal.

They assessed the results of treatment in 36 patients with 50 symptomatic limbs. The first 11 patients, who had 14 limbs treated, received treatment with urokinase and full-dose heparin, placement of a stent for iliac vein stenosis, and complete thrombus removal. The next 25 patients, who had 36 limbs treated, received urokinase and low-dose heparin followed by placement of the thrombectomy device and either early stent placement for stenosis or residual thrombosis in a short segment of the vein.

The investigators compared early treatment efficacy, duration of infusion, total urokinase dose, and complications in the two groups. They also used the Venous Disability Scale to (VDS) evaluate the thrombectomy patients during follow-up.

Successful results were observed in 86% of the 50 limbs, with similar rates in the two groups. They documented either complete or partial thrombolysis in 88% of the 50 limbs, with thrombolysis in 94% of the mechanical thrombectomy limbs and 71% in the limbs treated conventionally (P =.04).

The per-limb infusion time averaged 19.4 hours in the mechanical thrombectomy group and 31.1 hours in the conventionally treated group (P =.03). The total urokinase dose averaged 2.70 million units in the mechanical thrombectomy group and 5.65 million units in the conventional group (P =.01).

Bleeding events occurred in 4% of mechanical thrombectomy patients and 27% of those treated conventionally, a difference the investigators reported was not statistically significant (P =.08).

At short-term follow-up an average of 4.1 months after treatment, the mechanical thrombectomy group had a mean VDS of 0.63, and 94% of the 16 patients for whom data were available had scores indicating that disability was mild or absent.

In another study presented at the meeting, investigators found that the Trellis infusion catheter was not only clinically effective in patients requiring thrombolysis, but it was also cost effective.

Principal investigator Mahmood K. Razavi, MD, associate professor, cardiovascular interventional radiology, Stanford University Medical Center, Stanford, California, United States, and colleagues reviewed the data in the National Venous Registry, which is maintained by the device's manufacturer, Bacchus Vascular.

According to the researchers, the Trellis device offers isolation of treatment zone, mechanical drug dispersion and aspiration of dissolved clot.

In their study, 66 patients, 81% were treated in a single setting. The average treatment time was 18 minutes for the device-assisted treatment compared to an average of 2,880 minutes and range of 2 to 143 hours with the conventional treatment. The cost of treatment averaged $2,912 with device-assisted treatment and $6,187 with the conventional treatment.


[Presentation titles: Iliofemoral DVT: Pharmacomechanical Thrombolysis with Early Stenting Versus Conventional Pharmacologic Thrombolysis. Abstract 38. Clinical and Economic Evaluation of the Trellis Infusion System for Deep Vein Thrombosis: A Preliminary Analysis. Abstract 37]

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