Radiology

Case 29: Contributed by Dr. Amol Bhalekar

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Thrombus was also seen in the sapheno-femoral and sapheno-popliteal junctions. A hypercoagulability work-up including tests for proteins C and S, factor V Leiden mutation, anti thrombin III, homocysteine, lupus anticoagulant, antiphospholipid antibodies and prothrombin G20210A proved noncontributory. There was, however, history of consumption of oral contraceptive pills.

Endovascular treatment in the form of venous thrombolysis was planned for the acute deep venous thrombosis to decrease the thrombus load and avoid future post phlebitis syndrome.. After confirming the inferior vena cava to be normal in caliber and contour with good ante grade flow into the right atrium on IVC gram, a pre thrombolysis retrievable IVC filter (Optaease®, Cordis) was placed in the infra renal IVC through the right common femoral venous access (Fig 2).

A guide-wire was negotiated through the thrombosed veins upto the infra renal IVC. Thrombus aspiration was performed using a 5F guiding catheter. A continuous infusion of urokinase was done through an infusion catheter (infusion length 30cms) placed with its distal tip upto left common femoral vein (Fig.4)

Post-thrombolysis venogram revealed re-cannalisation of the left superficial femoral vein, left common femoral vein and the left external iliac vein with antegrade flow into the IVC (Fig 5).

Intravenous low molecular weight heparin was administered during thrombolysis. There was marked reduction in swelling over the next two days. Interestingly, the post thrombolysis venogram had revealed a narrowing of left common iliac vein involving its confluence with the IVC (Fig 6).

There was extensive opacification of the pelvic and para-vertebral venous collaterals. The IVC filter was seen in-situ in the infra renal IVC. Ultrasound examination revealed compression of the left common iliac vein by the right common iliac artery. There was localized thickening of the left common iliac vein at this site (Fig 7). This confirmed the diagnosis of May Thurner Syndrome.

IVC filter retrieval was done using a 15 mm snare (Fig 8 ).

The left common iliac vein narrowing was negotiated with a 0.035 Terumo guide-wire through a left 7F femoral venous access. A 10 X 80 mm expandable nitinol stent (Smart Control, Cordis) was deployed across the narrowed segment of the left common iliac vein. Post stenting venogram revealed widely patent stented segment with good antegrade flow into the IVC (Fig 9) with disappearance of pelvic collaterals.

The patient was started on aspirin 150 mg once daily and clopidogrel 75 mg once daily (to be continued for three months). On follow up, the patient was relieved of the left leg swelling. Ultrasound evaluation revealed good antegrade flow through the left common iliac vein stent into IVC.

DISCUSSION:

Venous thrombosis due to compression of the left common iliac vein by the overlying right common iliac artery was first described by Virchow in 1851, when he observed that iliofemoral vein thrombosis was five times more prevalent in the left leg than the right. Iliac vein compression remained relatively unknown until 1957, when May and Thurner characterized three types of intraluminal bands, or "spurs," within the compressed iliac vein that were hypothesized to be probable risk factors for the development of left-sided iliofemoral deep vein thrombosis (DVT) . Approximately 50%-60% of patients presenting with left-sided iliofemoral DVT have intraluminal webs in the common iliac vein from extrinsic compression . Therefore, IVCS is relatively common and there should be a high index of suspicion, particularly in a young woman who presents with acute ilio-femoral thrombosis of the left leg. With the advent of catheter-directed thrombolysis, iliac vein compression is emerging as a frequent finding at venography after ilio-femoral vein thrombolysis. IVCS tends to present in three distinct angiographic patterns: (i) focal common left iliac vein stenosis or short segment (< 3 cm) occlusion with collaterals ; (ii) acute ilio-femoral thrombosis in which the underlying lesion is unmasked after lytic therapy ; and (iii) chronic isolated thrombosis of the left common and external iliac vein with abundant collaterals arising from the common femoral vein . The natural impression of the iliac artery on the left iliac vein can be seen in asymptomatic patients; however, most symptomatic patients will demonstrate exuberant collateral venous pathways.

Although anticoagulation (heparin followed by oral anticoagulation) is currently considered the standard of care for the prevention of PE and recurrent DVT, this form of therapy does not protect the patient from the manifestations of the postthrombotic syndrome, which can appear months to years after the acute episode of DVT. The therapeutic goals for treating acute DVT include prevention of PE, restoration of unobstructed blood flow through the thrombosed segment, prevention of recurrent thrombosis, and preservation of venous valve function. Systemic anticoagulation with heparin followed by therapy with warfarin is the currently practiced mode of treatment. Such a regimen, however, does not promote lysis to reduce the thrombus load, nor does it contribute to restoration of venous valve function. Anticoagulation alone, therefore, does not protect the limb from the postthrombotic syndrome, which can occur months to years after the acute thrombotic event. Thrombolysis is an attractive form of therapy in acute deep venous thrombosis, because it provides the opportunity for prompt restoration of venous patency and preservation of venous valve function. This therapy can help prevent long-term sequelae of DVT.

Endovascular management of the May Thurner syndrome is safe and effective and may provide an alternative to surgical reconstruction or anticoagulation alone with the ability to re-establish normal venous flow by directly addressing the causative left common iliac venous obstruction. This should diminish the incidence of post-thrombotic syndrome and its long-term consequences.

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