정맥 스텐트 혈전증: 예방, 진단 및 관리 전략

Venous stent thrombosis represents one of the most challenging complications following venous stenting procedures, with significant implications for patient outcomes and quality of life. As venous stenting has become increasingly utilized for various venous obstructive conditions, understanding the prevention, early recognition, and effective management of stent thrombosis has gained paramount importance. This comprehensive guide explores the pathophysiology, risk factors, preventive strategies, diagnostic approaches, and contemporary management options for venous stent thrombosis across different clinical scenarios.

Pathophysiology of Venous Stent Thrombosis

Thrombosis Mechanisms

Multiple factors contribute to thrombus formation within venous stents:

• Virchow’s triad in stented veins:
• Endothelial injury: Caused by balloon angioplasty, stent deployment, and chronic vessel wall changes
• Stasis: Residual stenosis, suboptimal inflow/outflow, or poor stent expansion

• Hypercoagulability: Underlying thrombophilia, malignancy, or inflammatory states

• Stent-specific factors:

• Incomplete endothelialization
• Metal exposure to bloodstream
• Flow disturbances at stent edges
• Stent-vein diameter mismatch

• Stent fracture or deformation

• Temporal patterns:

• Early thrombosis (<30 days): Technical issues, inadequate anticoagulation
• Intermediate thrombosis (1-6 months): Neointimal hyperplasia, incomplete endothelialization
• Late thrombosis (>6 months): Progressive disease, external compression, patient factors

위험 요소

Several factors increase thrombosis risk:

• Patient-related factors:
• History of previous venous thromboembolism
• Thrombophilia (inherited or acquired)
• Active malignancy
• Recent surgery or trauma
• Immobility
• 비만
• Hormonal therapy

• Dehydration

• Anatomical and disease-related factors:

• Post-thrombotic syndrome
• Extensive venous disease
• Poor inflow vessels
• Limited outflow
• Extension below inguinal ligament

• Long-segment disease

• Procedural factors:

• Inadequate stent sizing
• Incomplete lesion coverage
• Residual stenosis
• Stent underexpansion
• Multiple overlapping stents

• Stent extension into areas of high mobility

• Post-procedural factors:

• Inadequate anticoagulation
• Poor compliance with therapy
• Dehydration
• Prolonged immobility
• Compression during sleep

예방 전략

Comprehensive prevention begins before intervention:

Pre-Procedure Risk Assessment

• Patient evaluation:
• Detailed history of previous thrombotic events
• Assessment of thrombotic risk factors
• Consideration of thrombophilia testing in selected cases

• Evaluation of anticoagulation options and contraindications

• Anatomical assessment:

• Comprehensive venous mapping
• Evaluation of inflow and outflow vessels
• Identification of potential high-risk anatomical features
• Planning for optimal stent placement

Technical Considerations During Intervention

• Stent selection:
• Appropriate sizing (typically 10-20% oversizing)
• Adequate length to cover entire lesion
• Dedicated venous stents preferred over arterial stents

• Consideration of stent design based on location

• Procedural techniques:

• Intravascular ultrasound (IVUS) guidance
• Complete lesion coverage
• Adequate pre- and post-dilation
• Confirmation of optimal expansion
• Avoidance of residual stenosis

• Management of inflow disease when present

• Intraoperative anticoagulation:

• Adequate heparinization during procedure
• Target ACT >200-250 seconds
• Consideration of direct thrombin inhibitors in HIT

Post-Procedure Anticoagulation Regimens

• Initial anticoagulation:
• Universal recommendation for all venous stent patients
• Options include LMWH, unfractionated heparin, or direct oral anticoagulants

• Immediate initiation post-procedure

• Long-term anticoagulation:

• Duration: Minimum 3-6 months, often longer

• Options:

  • Vitamin K antagonists (warfarin, target INR 2-3)
  • Direct oral anticoagulants (rivaroxaban, apixaban, edoxaban, dabigatran)
  • Low molecular weight heparin (particularly in cancer patients)

• 특수 인구:

• Thrombophilia: Consider indefinite anticoagulation
• Recurrent thrombosis: Higher intensity or indefinite therapy
• Cancer-associated: LMWH traditionally preferred, emerging evidence for DOACs

• Post-thrombotic syndrome: Extended duration common

• Antiplatelet therapy:

• Often added to anticoagulation initially
• Single antiplatelet may be continued after anticoagulation
• Limited evidence for optimal regimen
• Consideration of dual pathway inhibition in high-risk cases

Patient Education and Lifestyle Modifications

• Compliance counseling:
• Importance of consistent anticoagulation
• Recognition of bleeding signs

• Regular follow-up attendance

• Activity recommendations:

• Early ambulation post-procedure
• Regular exercise program
• Avoidance of prolonged immobility

• Proper positioning during sleep

• Compression therapy:

• Graduated compression stockings (20-30 mmHg)
• Proper fitting and application

• Duration of use (typically during daytime)

• Hydration and lifestyle:

• Adequate fluid intake
• Weight management
• 금연
• Avoidance of high-risk activities during initial period

Diagnosis of Venous Stent Thrombosis

Early recognition is essential for optimal management:

임상 프레젠테이션

• Symptoms:
• Acute onset or worsening of limb swelling
• Pain or heaviness in affected limb
• Return of pre-stenting symptoms
• Visible collateral veins
• Skin discoloration

• Venous claudication

• Signs:

• Unilateral edema
• Tenderness along stented segment
• Increased limb circumference
• Erythema or cyanosis in severe cases

• Phlegmasia cerulea dolens (rare)

• Differential diagnosis:

• In-stent restenosis without thrombosis
• Lymphedema
• Cellulitis
• Musculoskeletal conditions
• Arterial insufficiency

Diagnostic Imaging

• Duplex ultrasound:
• First-line imaging modality
• Findings: Absence of flow, non-compressibility, visible thrombus
• Limitations: Operator-dependent, limited visualization of iliac segments

• Advantages: Non-invasive, widely available, no contrast required

• CT venography:

• Excellent visualization of iliac and caval stents
• Findings: Filling defects, stent occlusion, collaterals
• Advantages: Comprehensive assessment, evaluation of surrounding structures

• Limitations: Contrast and radiation exposure

• MR venography:

• Alternative when CT contraindicated
• Findings: Signal voids, filling defects
• Advantages: No radiation, excellent soft tissue contrast

• Limitations: Artifacts from stents, longer acquisition time

• Conventional venography:

• Gold standard but invasive
• Often performed as part of treatment planning
• Direct visualization of thrombus and flow
• Allows pressure measurements and intervention

Laboratory Assessment

• D-dimer:
• Limited utility in stent thrombosis
• High sensitivity but poor specificity
• May be elevated from recent intervention

• More useful for excluding thrombosis when negative

• 응고 프로필:

• Assessment of anticoagulation adequacy
• INR for patients on warfarin
• Anti-Xa levels for LMWH or specific DOACs

• Identification of underlying coagulopathy

• Thrombophilia testing:

• Consider in recurrent thrombosis
• Timing important (acute phase affects results)
• Includes factor V Leiden, prothrombin mutation, antiphospholipid antibodies
• May influence long-term management decisions

Management Approaches

Treatment strategies depend on timing, extent, and clinical presentation:

Acute Stent Thrombosis (<30 days)

• Catheter-directed thrombolysis (CDT):
• First-line therapy for most cases
• Direct delivery of thrombolytic agents (tPA, urokinase)
• Duration: 24-48 hours typically
• Advantages: Gradual thrombus dissolution, lower bleeding risk

• Limitations: Time-intensive, ICU monitoring, bleeding risk

• Pharmacomechanical thrombectomy:

• Combines mechanical disruption with thrombolytics
• Devices: AngioJet, EKOS, Indigo, Aspirex
• Advantages: Faster than CDT alone, reduced lytic dose

• Considerations: Device selection based on thrombus characteristics

• Surgical thrombectomy:

• Rarely performed for venous stent thrombosis
• Considerations: Extensive thrombosis, contraindications to lysis
• Higher morbidity than endovascular approaches
• Limited to specialized centers

Subacute to Chronic Stent Thrombosis (>30 days)

• Recanalization techniques:
• Often more challenging than acute thrombosis
• May require specialized crossing tools
• Balloon angioplasty of organized thrombus

• Consideration of restenting

• Hybrid approaches:

• Combined pharmacomechanical and recanalization techniques
• Staged procedures may be necessary

• Individualized based on thrombus age and extent

• 보수적 관리:

• Consideration in asymptomatic or minimally symptomatic cases
• Anticoagulation optimization
• Compression therapy
• Collateral development monitoring

Post-Thrombectomy Considerations

• Underlying cause identification:
• Stent-related issues (underexpansion, fracture, migration)
• Inflow/outflow problems
• Missed lesions

• External compression

• Additional interventions:

• Extension stenting for edge stenosis
• Additional stents for missed lesions
• Balloon angioplasty for underexpansion

• Management of inflow disease

• Anticoagulation adjustment:

• Intensification of regimen
• Consideration of alternative agents
• Extended duration
• Addition of antiplatelet therapy

특별 시나리오

• Malignancy-associated thrombosis:
• Higher recurrence risk
• LMWH traditionally preferred
• Emerging evidence for DOACs in selected patients

• Consideration of IVC filter in recurrent thrombosis

• Thrombophilia-related thrombosis:

• Extended or indefinite anticoagulation
• Higher intensity regimens in selected cases
• Consideration of dual pathway inhibition

• Closer surveillance protocols

• Recurrent stent thrombosis:

• Comprehensive thrombophilia evaluation
• Consideration of alternative stent designs
• Evaluation for external compression factors
• Multidisciplinary management approach

Long-Term Outcomes and Follow-Up

Comprehensive surveillance is essential:

Surveillance Protocols

• Clinical follow-up:
• 2 weeks, 1, 3, 6, and 12 months, then annually
• Symptom assessment
• Physical examination

• Medication adherence evaluation

• Imaging surveillance:

• Duplex ultrasound at similar intervals
• CT or MR venography for suspected complications
• Earlier imaging for symptom recurrence
• IVUS for evaluation of in-stent abnormalities

Outcomes After Successful Management

• 기술적 성공률:
• Acute thrombosis: 70-90% with thrombolysis
• Subacute/chronic: 50-80% with recanalization

• Higher success with dedicated venous stents

• Long-term patency:

• Primary patency after successful thrombolysis: 50-70% at 1 year
• Secondary patency: 70-85% at 1 year

• Influenced by underlying etiology and risk factors

• Quality of life outcomes:

• Significant improvement with successful recanalization
• Return to baseline function in 60-80% of cases
• Persistent symptoms in some despite technical success

Prevention of Recurrence

• Optimized anticoagulation:
• Consideration of extended duration
• Regular monitoring of compliance and efficacy

• Individualized regimen based on risk factors

• Addressing mechanical factors:

• Correction of stent-related issues
• Management of external compression

• Optimization of inflow and outflow

• Patient education:

• Recognition of early symptoms
• Importance of follow-up adherence
• Lifestyle modifications for risk reduction

의료 면책 조항

중요 공지 사항: This information is provided for educational purposes only and does not constitute medical advice. Venous stent thrombosis is a serious medical condition that requires proper evaluation and management by qualified healthcare professionals. The treatment approaches discussed should only be implemented under appropriate medical supervision. Individual treatment decisions should be based on patient-specific factors, current clinical guidelines, and physician judgment. If you have undergone venous stenting and are experiencing symptoms such as sudden increase in limb swelling, pain, or discoloration, seek immediate medical attention as prompt diagnosis and treatment are essential. This article is not a substitute for professional medical advice, diagnosis, or treatment.

결론

Venous stent thrombosis represents a significant complication that can undermine the benefits of venous stenting procedures. A comprehensive approach to prevention, incorporating appropriate patient selection, optimal technical execution, and individualized anticoagulation regimens, is essential for minimizing this risk. When thrombosis occurs, prompt recognition and appropriate intervention, typically with catheter-directed thrombolysis or pharmacomechanical approaches, offer the best opportunity for stent salvage and symptom resolution. Long-term management requires attention to underlying causes, optimization of anticoagulation, and regular surveillance. With appropriate prevention strategies and management approaches, the impact of venous stent thrombosis can be minimized, preserving the benefits of venous stenting for patients with venous obstructive disease.