Endovascular Treatment of Iliofemoral and Femoral-Popliteal Deep Vein Thrombosis

Historical Background

Anticoagulation has long been considered the gold standard for treatment of lower extremity deep vein thrombosis (DVT). This therapy is effective at preventing DVT extension, pulmonary embolism, and DVT-related death. However, because anticoagulation does not dissolve thrombus, clot resolution is slow, relying on the intrinsic thrombolytic pathways. Although this is sufficient for isolated calf DVT, prolonged venous obstruction can lead to pronounced long-term morbidity in those with more proximal iliofemoral DVT. Five-year follow-up of patients with iliofemoral DVT treated with anticoagulation alone demonstrates that up to 95% develop venous hypertension, 90% display venous reflux, 15% exhibit venous claudication, and another 15% develop venous ulceration. Poor quality of life has been substantiated by further study.

Early clot removal with surgical venous thrombectomy for iliofemoral DVT was first reported by Fogarty and colleagues in 1966. Venous thrombectomy was demonstrated to improve long-term patency and substantially reduced the occurrence of postthrombotic symptoms and morbidity. Nonetheless, this technique was highly invasive, which prevented widespread acceptance and implementation.

Systemic thrombolysis was assessed as an alternative to venous thrombectomy, with improvement in patient outcomes and venous patency correlating directly with the degree of lysis. Complete lysis, however, was only achievable in up to 50% of patients with nonocclusive thrombus and 10% of patients with occlusive thrombus. Clinical applicability of this strategy was further limited by unacceptably high rates of bleeding complications. Thus for nearly a decade, strategies of early thrombus removal were abandoned, because the immediate risks of the procedure outweighed the significant long-term morbidity of iliofemoral DVT.

In 1994 Semba and Dake were the first to demonstrate the effectiveness of catheter-directed thrombolysis using urokinase in the treatment of 21 patients with ileofemoral DVT. Complete lysis was achieved in 18 patients (72%) and partial lysis in 5 patients (20%). There were no major complications or clinically detectable PE. At 3 months, 12 limbs were studied with Doppler ultrasonography and veins were patent in 92%. Subsequent advancements in endovascular techniques have demonstrated the ability to achieve more effective clot removal while limiting systemic thrombolytic drug exposure and bleeding risks. In 2001 Kasirajan and colleagues demonstrated the potential value of percutaneous mechanical thrombectomy to achieve symptomatic relief and clot removal in ileofemoral DVT using a rheolytic AngioJet catheter (Medrad, Inc., Warrendale, Pa.). In 2006 Lin demonstrated that additional infusion of a thrombolytic agent via the AngioJet catheter increased the effectiveness of percutaneous mechanical thrombectomy in a technique referred to as power pulse spray mode. With limited risk and significant improvements in long-term clinical outcomes and venous patency, endovascular interventions should be considered for all healthy patients with proximal lower extremity DVT, good functional status, and reasonable life expectancy.

Preoperative Preparation

• Preoperative imaging. Because isolated calf DVT is best managed with anticoagulation, thrombus within the iliofemoral system should be documented before the decision to intervene. Although venography remains the gold standard for both the diagnosis and the assessment of DVT, this test is invasive and is reserved as a confirmatory study during intervention ( Fig. 58-1 ). Alternatively, preoperative imaging with lower extremity duplex ultrasonography is noninvasive, convenient, and cost effective for the diagnosis of DVT ( Fig. 58-2 ). Duplex imaging has a sensitivity and a specificity of 95% and 97%, respectively, for diagnosing proximal lower extremity DVT. Ultrasonographic evidence of DVT includes noncompressible or partially compressible venous segments with continuous venous flow patterns that lack normally phasic flow variation.

  
  

• Thrombophilia evaluation. Evaluation for inherited thrombophilia is indicated for patients who present under 50 years of age with an unprovoked DVT, a family history of thromboembolism, unusual thrombus location, or with a recurrent DVT. Screening should include evaluation for protein C or S deficiency, antithrombin deficiency, factor V Leiden, protein C resistance, prothombin gene mutation 20210A, hyperhomocysteinemia, and antiphospholipid antibody syndrome. Diagnosis of a thrombophilic disorder should prompt referral to a hematologist for long-term anticoagulation. A history of oral contraceptive use and malignancy should be sought, and evaluation for occult cancer should be considered.

• Anticoagulation. Therapeutic anticoagulation with unfractionated heparin or low-molecular-weight heparin should be administered preoperatively once the diagnosis is established and blood is drawn for evaluation of an inherited thrombophilia. Full anticoagulation should continue throughout the procedure and for at least 6 months thereafter. Longer periods of anticoagulation may be necessary for treatment of an underlying thrombophilia.

Pitfalls and Danger Points

• Hemorrhagic complications. Bleeding complications have been substantially reduced with the introduction of catheter-directed endovascular therapy for thrombolysis. The use of thrombolytics enhances the success of intervention, but if the risk is deemed too high, percutaneous mechanical thrombolysis (PMT) may be performed with saline infusate alone.

• Recurrent DVT. Treatment of recalcitrant thrombus and stenting of underlying lesions may reduce the risk of recurrent DVT.

Operative Strategy

Inferior Vena Cava Filters

Retrievable filters may be considered to prevent pulmonary embolization as the clot is disrupted ( Fig. 58-3 ). Approximately 30% to 40% of patients have thrombus in filters retrieved after intervention. The true incidence of symptomatic emboli is unknown but appears to be low.

If a filter is used, it should be placed prior to intervention below the renal veins via a delivery route that is free of thrombus; most often from the contralateral femoral vein or right internal jugular vein. The filter can be retrieved at the end of the procedure or later if thrombus remains or a contraindication to anticoagulation exists.

Operative Technique