Overview
Definition:
Endovascular thrombectomy (EVT) for acute deep vein thrombosis (DVT) is a minimally invasive interventional procedure aimed at physically removing or dissolving a blood clot from a major vein
It is an alternative to systemic anticoagulation and conservative management, particularly for severe or extensive DVTs that pose a significant risk of post-thrombotic syndrome (PTS) or pulmonary embolism (PE).
Epidemiology:
Acute DVT affects an estimated 1 in 1,000 individuals annually
While systemic anticoagulation is the mainstay, a subset of patients with extensive iliofemoral DVT, phlegmasia cerulean dolens, or acute limb ischemia may benefit from aggressive clot removal
The incidence of PTS can be as high as 50% in some patient groups with extensive DVTs, highlighting the need for effective interventions.
Clinical Significance:
EVT for acute DVT is crucial for preventing the debilitating long-term consequences of PTS, such as chronic pain, swelling, skin changes, and venous ulcers
It also plays a role in reducing the risk of life-threatening PE, particularly in patients with massive DVTs or contraindications to thrombolysis alone
For surgical residents, understanding the indications, techniques, and potential complications of EVT is vital for managing complex venous thromboembolic disease.
Indications
Indications For Evt:
Acute iliofemoral DVT (May-Thurner syndrome or other causes) with symptoms of significant venous obstruction, such as extensive limb swelling, pain, and potential for ischemia
Provocative factors include phlegmasia cerulean dolens or impending limb ischemia
Patients with a high risk of developing severe PTS despite anticoagulation
Failed conservative management with worsening symptoms
PE prophylaxis in selected high-risk patients with extensive DVTs.
Contraindications:
Active bleeding or high bleeding risk
Recent major surgery or trauma
Uncontrolled hypertension
Severe coagulopathy
Advanced malignancy with short life expectancy
Significant comorbidities precluding the procedure or anesthesia
Absence of identifiable thrombus amenable to intervention.
Patient Selection:
Careful patient selection is paramount
Patients with acute, extensive DVTs, particularly in the iliofemoral system, who are relatively young and have a good functional status are ideal candidates
Risk-benefit analysis considering bleeding risk, potential for PTS, and PE is essential
Multidisciplinary discussion involving vascular surgeons, interventional radiologists, and hematologists is often beneficial.
Preoperative Preparation
Imaging Assessment:
Duplex ultrasound is the initial modality for diagnosis and assessing extent
CT venography or MR venography may be used for more detailed anatomical assessment of the thrombus and venous system, especially for iliofemoral involvement and to identify potential mechanical obstructions like May-Thurner syndrome.
Anticoagulation Strategy:
Heparinization is typically initiated prior to the procedure to prevent propagation of existing thrombi and further clot formation
The type and duration of anticoagulation post-EVT will depend on the underlying cause of DVT and patient factors.
Multidisciplinary Consultation:
Close collaboration with interventional radiology is fundamental
Consultation with hematology for underlying thrombophilia workup and management, and cardiology if PE is a concern, is often indicated
Anesthesia consultation may be required for monitored anesthesia care or general anesthesia.
Procedure Steps
Access Site Selection:
Antegrade or retrograde venous access is chosen based on the location of the thrombus and anatomy
Common access sites include the common femoral vein, popliteal vein, or internal jugular vein
Contralateral access may be used if ipsilateral access is compromised.
Thrombectomy Techniques:
Mechanical thrombectomy devices (e.g., AngioJet, Trellis-8) are used to physically aspirate or macerate the clot
Pharmacomechanical thrombolysis involves combining mechanical disruption with localized infusion of thrombolytic agents (e.g., urokinase, tPA) to accelerate clot lysis
Catheter-directed thrombolysis (CDT) involves placing catheters within the thrombus and infusing thrombolytics over several hours or days.
Adjunctive Procedures:
Balloon angioplasty and stenting may be required if significant venous stenosis or occlusion is identified as a contributing factor (e.g., May-Thurner syndrome) and to ensure patency after thrombus removal
IVC filter placement may be considered in patients with extensive proximal DVTs and contraindications to anticoagulation, or if PE occurs during the procedure.
Postoperative Care And Follow Up
Monitoring:
Close monitoring for bleeding, including access site hematoma, and systemic anticoagulation effects is crucial
Vital signs, limb circumference, pain, and signs of reperfusion or ischemia are assessed regularly
Post-procedure imaging (duplex ultrasound) is performed to assess venous patency.
Anticoagulation And Pharmacotherapy:
Continuation or initiation of therapeutic anticoagulation is essential to prevent re-thrombosis
The choice of anticoagulant (e.g., LMWH, DOACs, warfarin) depends on individual patient factors and guidelines
Thrombolytic therapy management is critical for minimizing bleeding risk.
Long Term Management:
Patients require long-term follow-up to monitor for recurrence of DVT, development of PE, and the progression of PTS
Regular clinical assessment and duplex ultrasound are performed
Graduated compression stockings are typically prescribed to manage symptoms of PTS and prevent venous stasis
Management of risk factors for VTE is a key component of long-term care.
Complications
Procedure Related Complications:
Bleeding at the access site or systemically (hemorrhage)
Vascular injury (dissection, perforation)
Embolization of thrombus to the lungs (PE)
Allergic reactions to contrast or thrombolytics
Nerve injury
Arteriovenous fistula formation.
Post Procedure Complications:
Post-thrombotic syndrome (PTS) is a significant long-term complication, characterized by chronic pain, swelling, hyperpigmentation, and venous ulcers
Re-thrombosis of the treated vein
In-stent stenosis if stenting was performed
Superficial thrombophlebitis.
Prevention And Management:
Meticulous technique during the procedure can minimize vascular injury
Careful titration of anticoagulation and thrombolytics, along with appropriate use of IVC filters, can reduce embolic complications
Prompt recognition and management of bleeding are critical
Aggressive management of PTS with compression stockings and early ambulation is important
Regular follow-up helps detect and manage complications.
Key Points
Exam Focus:
Understand indications for EVT in acute DVT, particularly iliofemoral
Differentiate between mechanical thrombectomy, CDT, and pharmacomechanical thrombolysis
Know common access sites and potential complications like PE and PTS
Recognize the role of stenting in venous stenosis.
Clinical Pearls:
Early identification of extensive iliofemoral DVT is crucial
Multidisciplinary approach is best for patient selection and management
Aggressive treatment may significantly reduce PTS burden
Remember that anticoagulation is always a cornerstone of DVT management, even with EVT.
Common Mistakes:
Overestimating benefit in patients with limited life expectancy or very chronic DVTs
Inadequate post-procedure anticoagulation leading to re-thrombosis
Insufficient patient selection leading to high complication rates
Delaying definitive treatment due to indecision
Neglecting long-term management of PTS.