Currently, no controlled clinical trials have shown a survival benefit of thrombolytics over heparin and warfarin. Some randomized trials suggest reduced morbidity from PPS if complete clot lysis is achieved with thrombolytics.2 However, as the short-term benefits of lytic agents are generally small and the long-term benefits remain to be proved, the use of these drugs has very limited indications. In practice, they are rarely used to treat a DVT. Thrombolytics have a significantly greater bleeding risk, including fatal intracerebral hemorrhage, than heparin or warfarin. Currently, lytic drugs such as streptokinase, urokinase, and tissue plasminogen activator (tPA) should be restricted to extensive iliofemoral thrombosis such as phlegmasia cerulea dolens in patients with a low risk of bleeding. Systemic thrombolysis may fail to lyse iliofemoral clots due to local stagnant blood flow; in such cases, intravascular catheter-directed thrombolysis is recommended.
An inferior vena cava filter can be placed to prevent a PE when oral anticoagulation is contraindicated, a DVT persists or propagates despite adequate medical treatment, embolization occurs after 1 to 2 weeks of therapeutic anticoagulation, or there is significant bleeding with the use of anticoagulants. Given the greater than 95 percent patency rate of a Greenfield filter at 1 year after placement, its indications can be expanded. A free-floating, nonadherent iliofemoral thrombus greater than 5 cm has an up to 60 percent chance of forming a PE; in such cases, filter placement should be considered.
Surgical thrombectomy was enthusiastically received in previous decades, but owing to high rates of rethrombosis and failure to prevent postphlebitic sequelae due to valve incompetency, it is rarely considered today. When conventional therapy for DVT is contraindicated or ineffective, thrombectomy followed by heparin can achieve long-term patency. Surgical treatment of a DVT is typically reserved for patients when limb viability is jeopardized by a massive venous clot, such as a persistently ischemic leg secondary to phlegmasia cerulea dolens.
The ED management of patients who are adequately anticoagulated but present with propagation or a new clot is fairly straightforward. Since LMWH is significantly more effective for treating DVT, these patients should all be started on LMWH with urgent follow-up by hematology (or, if otherwise indicated, admission). If they fail LMWH or have large free-floating thrombi, a Greenfield filter should be emergently placed by radiology. The investigation of these patients for a hypercoagulable state or malignancy need not be initiated in the ED. There is no evidence in the literature that increasing anticoagulation beyond an INR of 3 is at all effective in treating refractory DVT.
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