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Mechanical thrombolysis for deep vein thrombosis

Christopher Davis, MPAS, PA-C, RT; Asim Khwaja, MD

The authors practice at Associated Radiologists LTD, Banner Baywood Medical Center, Mesa, Arizona. They have indicated no relationships to disclose relating to the content of this article.

CASE

A 58-year-old Hispanic female presented to the emergency department (ED) with left lower extremity pain and edema that had been present for the previous 4 days. The pain had had an acute onset. The patient had no history of travel, immobilization, or other risk factors for hypercoagulation. She denied chest pain, shortness of breath, and cough. Physical examination in the ED revealed that her left lower extremity was swollen up to the proximal thigh; her calf was tender, and her skin was warm. Nonpitting edema was also evident. Laboratory testing revealed an elevated D-dimer level. Diagnostic imaging tests included Doppler ultrasonography (see Figure 1) and CT of the abdomen and pelvis (not shown). What does the sonogram reveal?

DISCUSSION

Figure 1 demonstrates lack of compression of the common femoral vein; ultrasonography revealed extensive deep vein thrombosis (DVT) involving the left common femoral vein to the left popliteal vein, with an absence of compression and flow. CT indicated a left external iliac/common femoral DVT with transition to the left common iliac vein.

INTERVENTIONAL RADIOLOGY Mechanical thrombolysis with a Trellis-8 device in the interventional radiology suite was chosen as definitive treatment for this patient’s acute DVT. She was placed in the prone position, and the left popliteal fossa was prepped and draped in the usual sterile fashion. Under ultrasound guidance, the left popliteal vein was accessed using the Seldinger technique. Following contrast administration, a nonocclusive thrombus was found to be present in the common femoral vein and in the left external iliac vein (see Figure 2).

Following left leg venography, percutaneous venous thrombolysis was performed. The Trellis catheter was placed into the left iliac and femoral veins, with the treatment zone measuring 30 cm. Using the standard protocol, 6 mg of tissue plasminogen activator (tPA) was instilled into the treatment zone in 1-mg increments, with a total run time of approximately 10 minutes. A posttreatment venogram showed resolution of the common femoral vein thrombus, with some residual thrombus noted in the left external iliac vein. A high-grade stricture was identified in the left common iliac vein. This stricture was treated with 8- and 10-mm balloon angioplasty and placement of two overlapping 14-mm38-mm and 14-mm36-mm stents.

Following thrombolysis and stenting, venography was again performed (see Figure 3). The posttreatment venogram showed brisk antegrade flow through the left iliofemoral venous system without significant residual stenosis or significant thrombus evident.

STANDARD TREATMENT VERSUS MECHANICAL THROMBOLYSIS Traditional treatment of DVT is based on the use of anticoagulants to prevent the formation of new clots or the propagation of existing clots, thereby decreasing the likelihood of fatal pulmonary embolism. Anticoagulation is achieved with an initial regimen of heparin and warfarin (Coumadin, Jantoven) given on day 1. The heparin is continued until the warfarin is at a therapeutic level, demonstrated by an international normalized ratio between 2.0 and 3.0. When using low molecular weight (LMW) heparin, warfarin should also be initiated on day 1.¹ The use of LMW heparin is becoming more common, as it offers greater anticoagulation predictability. The preferred length of time for the patient to remain on anticoagulant therapy is debated, but standard protocols require a minimum of 6 months and longer depending on risk factors, age, and comorbid conditions. In patients with idiopathic, first-episode DVT, anticoagulation therapy should continue for at least 6 months.² Chronic DVT may require anticoagulation therapy indefinitely.

The long-term sequelae of DVT include postthrombotic syndrome (PTS), which can lead to significant disability, quality-of-life impairment, and socioeconomic costs. Stand-alone anticoagulant therapy fails to prevent PTS in a significant proportion of patients. Within 1 to 2 years of a symptomatic DVT, 20% to 50% of patients experience PTS. This condition can be clinically characterized by chronic pain, swelling, and—rarely—ulcerations. Although not completely understood, the pathology of PTS involves the acute thrombus, associated inflammatory mediators, and the process of venous recanulization, leading to damage of venous valves and valvular incompetence.³ Treatment is costly and difficult.

The treatment of acute DVT with thrombolysis and mechanical thrombectomy aims primarily at decreasing the risk of valvular insufficiency and postthrombotic syndrome in the long term, while also providing acute symptom relief.⁴ Previous, catheter-directed thrombolysis often required admission to an ICU and long infusions of tPA, with the associated potential systemic complications. The adjunct use of mechanical thrombectomy with localized tPA infusion results in shorter treatment times and thrombus debulking that can often be accomplished in a single 1- to 2-hour treatment. The results of decreased swelling and decreased pain are often immediately noted, with most patients experiencing significant resolution of their symptoms within 1 to 2 days.

Treatment following thrombolysis is to continue a regimen of anticoagulation for 6 to 12 months, depending on the cause of the DVT and comorbid conditions. Additionally, compression stockings are often prescribed as a prophylactic measure.

OUTCOME This 58-year-old patient’s symptoms of pain and left lower extremity swelling resolved significantly following the procedure. Measurements of the calf circumference from initial presentation to day of discharge decreased from 38 cm to 34 cm. The erythema and edema also diminished. The hospital course was uncomplicated and lasted 4 days. A hypercoagulability workup revealed no discernable cause for the DVT, and the patient was discharged with anticoagulation treatment for 6 months for an idiopathic first episode thrombus. She has had an uneventful course following her DVT and was able to donate a kidney to her husband.

Julie Vajnar, PA-C, RT, department editor

REFERENCES

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