Low-Dose Alteplase to Treat Blood Clots in Deep Leg Veins

Summary

This study will test the effectiveness of low-dose recombinant tissue plasminogen activator (rtPA, or alteplase) in dissolving blood clots in deep leg veins. Alteplase is used to clear blood clots in coronary arteries in patients having heart attacks. Blood clots can develop in the deep leg veins causing pain and swelling and may break loose and lodge in the lungs. Current routine treatments use anticoagulants such as heparin stop the clots from enlarging and prevent clots from moving to the lung but do not reliably dissolve clots in the leg.In an earlier study we showed that rtPA could be used to actually dissolve the clots. This study will determine whether lower doses of rtPA can dissolve clots with fewer bleeding complications than the current higher-dose regimens.

Patients 18 years of age and older who have blood clots in a deep vein of the pelvis or leg may be eligible for this study if they have had symptoms for 14 days or less and if they have never had clots in their deep veins before.

Participants are admitted to hospital for up to 5 days. On the first treatment day, the patient has a venogram to show the location of the clots. The radiologist injects an x-ray contrast material into a small vein in the foot and watches the dye by x-ray as it moves up the leg, revealing the clot(s). A catheter (plastic tube) is then inserted into a vein either behind the knee, in the groin, or in the neck, and advanced until it reaches the clots. When the catheter is in place, rtPA is injected while the radiologist watches the vein under the x-ray image. The amount of rtPa needed will depends on the size of the clot. Up to five venograms may be done if the clot requires the maximum four rtPA treatments allowed in this study. During the treatments, patients receive standard doses of heparin, given continuously by vein, After completion of treatments, anticoagulation is continued through use of a low molecular weight heparin (usually enoxaparin) given by subcutaneous injection as a transition medication during conversion to anticoagulation with warfarin ( also known as coumadin), another blood thinner, taken by mouth. Patients continue taking warfarin for 6 months.

During thrombolytic therapy, blood samples are drawn shortly before the first dose of rtPA and at five time points afterward to measure the rtPA in the circulation and other factors that indicate whether the rtPA is affecting clotting ability. Blood also is drawn at least once a day to monitor heparin levels.

To evaluate the impact of treatment on the function of the leg, patients return to the Rehabilitation Medicine Department and Radiology department at about 6 weeks (4 to 8 week ) and 6 months for clinical and imaging evaluation of impact of therapy on venous function.

The objectives are to determine how well this treatment will restore venous function and whether this can be done safely- without causing bleeding complications, which have been the main risks of previous thrombolytic treatments.

Conditions

• Acute Deep Venous Thrombosis of the Lower Extremity

Interventions

DRUG

Alteplase (Activase, Genentech)

Dose of Alteplase will not exceed 10 mg/d/leg and is delivered in a concentration of 100ug/mL. The actual dose delivered is based upon the length of the thrombosed vein and 1 mL is injected directly into each centimeter of a thrombosed vein in a lower extremity. The treatment will be repeated up to 4 times over a 4 day period.

Sponsors & Collaborators

• National Institutes of Health Clinical Center (CC)

  collaborator NIH

• Richard Chang, M.D.

  lead NIH

Principal Investigators

• Richard Chang, MD · NIH Clinical Center/ Department of radiology and Imaging Sciences

Study Design

Allocation

NA

Purpose

TREATMENT

Masking

NONE

Model

SINGLE_GROUP

Eligibility

Min Age

18 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2004-05-31

Primary Completion

2010-03-31

Completion

2014-10-31

Countries

• United States

Study Locations