Endovascular Treatment of Deep Vein Thrombosis

Indications

•Imaging-proven symptomatic DVT in the IVC, iliac, common femoral, and/or femoral vein in a recently ambulatory patient with DVT symptoms for less than 28 days or in whom there is strong clinical suspicion for recently formed (less than 28 days) DVT

Contraindications

•Active internal bleeding or disseminated intravascular coagulation

•Recent cerebrovascular event (including TIA), neurosurgery (intracranial, spinal), or intracranial trauma (<3 months)

•Contraindication to anticoagulation

•Recent cardiopulmonary resuscitation, major surgery, obstetrical delivery, organ biopsy , major trauma, or cataract surgery (<7–10 days)

•Intracranial tumor or other intracranial lesion

•Uncontrolled hypertension: systolic BP >180 mmHg, diastolic BP >100 mmHg

•Recent major GI bleeding (<3 months)

•Serious allergic reaction to thrombolytic agent, anticoagulant, or contrast media

•Severe thrombocytopenia

•Known right to left cardiac or pulmonary shunt or left heart thrombus

•Inability to tolerate procedure due to severe dyspnea or acute medical condition

•Suspicion for infected venous thrombus

•Moderate-to-severe renal failure

•Pregnancy or lactation

•Severe hepatic dysfunction

•Bacterial endocarditis

•Diabetic hemorrhagic retinopathy

BP blood pressure, DVT deep vein thrombosis, GFR glomerular filtration rate, TIA transient ischemic attack

Clinical severity and anatomic extent should be taken into account with previously published data when deciding if CDT is necessary. Patients can be categorized into groups based on clinical severity of DVT. Group A comprises of patients in which urgent thrombolysis is indicated to prevent life- or limb-threatening complications of acute DVT. Group A includes those patients with progressive IVC thrombosis or phlegmasia cerulea dolens or if IVC thrombosis presents increased risk of fatal PE or renal failure. Group B includes patients where initial anticoagulation failed to achieve therapeutic objectives including DVT progression and worsening of clinical severity/symptoms. Group C is reserved for patients with symptomatic DVT for which anticoagulation is administered with the purpose of preventing PTS. Aggressive therapy should be pursued for patients in Group A. A low threshold for exclusion should be applied for patients in Group B or C particularly if there is a significant risk for complications [26, 28, 29].

Anatomic extent of DVT is an important consideration in appropriately selecting patients for CDT. Historically, proximal DVT refers to thrombus within the popliteal, femoral, deep femoral, common femoral, or iliac veins or the IVC. Patients with DVT in the iliac vein or common femoral vein, also referred to as iliofemoral DVT, experience much more clinical severity and experience higher rates of recurrent VTE. Distal or isolated calf DVT is confined in the calf veins below the popliteal vein (Table 25.2).

Table 25.2

CDT decision criteria based on clinical presentation

Clinical presentation	Bleeding risk
Clinical presentation	Low	Moderate	High
Acute limb threat	Yes	Yes	Surgery
Extensive IVC thrombosis	Yes	Yes	No
Iliofemoral DVT with progression of symptoms or anatomic extent despite anticoagulation (second-line therapy)	Yes	No	No
Iliofemoral DVT to prevent PTS (first-line therapy)	Maybe	No	No
Femoropopliteal or isolated calf DVT to prevent PTS	No	No	No

CDT should generally not be pursued in patients where the extent of the DVT does not include the IVC, iliac vein, or common femoral vein given the risks of therapy and the paucity of data showing a compelling benefit. Patients presenting with an iliofemoral DVT and low bleeding risk are the group that is most likely to achieve clinical benefit (Fig. 25.1). Patients with asymptomatic or isolated calf DVT are not candidates for endovascular therapy [27]. Patients that have a short life expectancy or are unable to ambulate are not likely to benefit from CDT. Additionally, given the risk/benefit profile and inconveniences, fully functional patients may decline aggressive therapy. Regardless, the benefits versus risks and treatment alternatives should be thoroughly discussed [4, 30, 31].

Fig. 25.1

Twenty-four-year-old male status post trauma to the right knee presented to the emergency department with right lower extremity swelling. Access was obtained via the right popliteal vein. Venogram performed via the right popliteal vein demonstrates multiple filling defects and venous expansion (a, b) in the right popliteal, right femoral, and right common femoral veins compatible with acute thrombus formation. Catheter-directed thrombolysis was not pursued because the patient had a recent spinal surgery, and iliofemoral veins were patent and without evidence of thrombus (not shown). The patient was managed with therapeutic anticoagulation

Interventional Options for Acute Deep Vein Thrombosis

Technological advances in catheter technology and device development coupled with literature-supporting minimally invasive interventional techniques have led to an aggressive approach in the treatment of acute DVT. Advances in noninvasive imaging modalities including Duplex ultrasound, CT, and MRI have provide enhanced characterization of the extent of thrombus particularly in the IVC and iliac venous system. Improvements in catheter-based delivery systems have been made such that intrathrombus drug delivery is more efficient. Device development including but not limited to the AngioJet (Boston Scientific, Marlborough, MA), Arrow-Trerotola percutaneous thrombolytic device (Arrow, Reading, PA), and AngioVac (Angiodynamics, Latham, NY) has served a significant adjunctive tool to acute thrombus removal.

Multiple endovascular techniques have evolved for the treatment of acute thrombus. Current endovascular techniques used include catheter-directed thrombolysis (CDT) , percutaneous mechanical thrombectomy (PMT) , and percutaneous catheter-directed thrombolysis (PCDT) . PCDT can then be further subdivided into first- and second-generation techniques which will be discussed in the following sections.

Catheter-Directed Thrombolysis (CDT)

Catheter-directed thrombolysis refers to the delivery of thrombolytic drug directly into thrombus using a catheter or catheter-based device that is embedded within the thrombus using imaging guidance [32]. This was the first endovascular method utilized for treatment of acute DVT. CDT achieves a higher intrathrombus drug concentration and reduced systemic drug concentration which allows thrombolytics to penetrate into a completely occlusive thrombus [33]. Additional benefits include reduced overall thrombolytic agent dose systemically, treatment time, and complication rates. Further, adjunctive techniques can be utilized to evaluate and treat venous abnormalities that may have provoked the initial thrombotic event.

Access is gained via either an internal jugular vein, popliteal vein, or other veins of the affected extremity. Ideally a non-obstructed, non-thrombosed vein is accessed. The popliteal vein serves as a convenient access point owing to its ease for achieving hemostasis through manual compression following intervention. The jugular vein serves as a good access site as well; however, wire and catheter manipulation are against the direction of the venous valves. The jugular venous access site requires longer wires and catheters. Serial venograms and/or intravascular ultrasound (IVUS) is used and obtained to evaluate the extent of thrombus . Next, a multi-side hole infusion catheter is placed within the thrombus, and a fibrinolytic drug is infused. The most commonly used fibrinolytic drug is recombinant tissue plasminogen activator (rt-PA, Genentech, San Francisco, CA). Although this drug is not FDA-approved for DVT therapy, suggested dosing of rt-PA is weight-based and is 0.01 mg/kg/h for up to a maximum of 1.0 mg/h for approximately 6–24 h. While infusing lytics, the patient is continuously monitored in a high-acuity bed, and a CBC, fibrinogen, and PTT are drawn every 6 h. If laboratory parameters deviate from expected ranges, infusion is temporarily or permanently discontinued. After infusion serial venograms are obtained to determine if further lysis needs to be performed or if the catheter needs repositioning. Serial venograms also serve to identify any venous anatomic lesion that needs further treatment with balloon venoplasty and/or stent placement (Fig. 25.2).

Fig. 25.2

Sixty-three-year-old male with history of previous right lower extremity below the knee amputation with acute onset of left lower extremity pain and swelling. Duplex ultrasound (not shown) demonstrated acute thrombus in the left popliteal, left femoral, and left common femoral veins. Due to concern for thrombus extending into the iliofemoral system, a venogram was pursued. Vascular access was obtained in the left popliteal vein. Digital subtracted contrast venograms were obtained demonstrating acute thrombus extending from the left popliteal/femoral vein (a, b) into the left common femoral and left iliac vein (c). An infusion catheter was placed into the thrombus, and rt-PA was administered at a rate of 0.01 mg/kg/h for a total of 12 h. The patient returned for a repeat venogram. Percutaneous mechanical thrombectomy was performed in addition to catheter-directed thrombolysis with follow-up venograms showing resolution and clearing of the thrombus burden (d–f)

Stent placement is typically reserved for the common iliac and external iliac anatomic abnormalities. At times it is necessary to extent stent placement into the common femoral vein. Currently, there are no venous stents that have FDA approval. If stent placement is necessary, an uncovered, self-expandable bare metal stent is favored because they have sufficient hoop strength and allow inflow from venous tributaries. Drawbacks or limitations to CDT are its long infusion times required to obtain complete thrombus treatment , the risk of major bleeding (see below), and hospital resources utilized. Following catheter-directed thrombolysis, patients should be anticoagulated and monitored closely (Table 25.3).

Table 25.3

Technical considerations in performing catheter-directed thrombolysis

–Apply rigorous clinical evaluation to identify patients with major clinical manifestations of DVT, major anatomic thrombus extent, and a very low risk of bleeding

–Ensure that the effect of oral anticoagulants or long-acting (e.g., once daily) parenteral anticoagulants is subtherapeutic before thrombolysis is initiated

–Routinely use ultrasound guidance for venous access, to prevent bleeding from inadvertent arterial punctures

–Use infusion CDT when the popliteal vein has poor inflow, to optimize thrombus removal from the non-axial veins; consider single-session pharmacomechanical therapy when there is good popliteal venous inflow

–Use weight-based TPA infusions at 0.01 mg/kg/h, not to exceed 1.0 mg/h

–Keep TPA infusion durations to a minimum, ideally less than 24–30 h

–Target unfractionated heparin to the subtherapeutic range during thrombolysis, to avoid overshoot which could cause bleeding

–Ensure that iliac vein obstructive lesions (e.g., May-Thurner syndrome) are treated

–Closely monitor anticoagulant therapy during the weeks after CDT to avoid preventable cases of re-thrombosis. If possible, utilize LMWH for 1–3 months after CDT

–Avoid routine placement of IVC filters for CDT, but if a filter is placed, be sure to remove it in a timely fashion (assuming the patient can still be anticoagulated)

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