Low-Dose Alteplase to Treat Blood Clots in Deep Leg Veins
Status:
Completed
Trial end date:
2014-10-01
Target enrollment:
Participant gender:
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.
Phase:
Phase 2
Details
Lead Sponsor:
Richard Chang, M.D.
Collaborator:
National Institutes of Health Clinical Center (CC)