Indications

Indication	Class	Notes
Acute iliofemoral DVT (<14 days) with severe symptoms (limb swelling, pain, phlegmasia)	Class IIa	Strongest indication; symptoms uncontrolled by anticoagulation alone
Iliofemoral DVT with phlegmasia cerulea dolens	Urgent/emergent	Risk of venous gangrene; immediate thrombectomy ± fasciotomy
Symptomatic DVT in patients with high functional demand (young, active)	Class IIa	Shared decision-making; quality-of-life benefit vs. bleeding risk
IVC/iliocaval thrombosis from extrinsic compression (May-Thurner syndrome)	Class IIa	IVUS to confirm compression; stenting after thrombus removal
Femoropopliteal DVT	Class IIb	Less certain benefit; consider if severe symptoms or contraindications to anticoagulation
Isolated below-knee DVT	Not indicated	Anticoagulation alone; CDT adds risk without proven benefit

Contraindications

Type	Contraindication
Absolute	Active intracranial hemorrhage · Recent ischemic stroke (<3 months) · Recent brain/spine/eye surgery (<10 days) · Intracranial neoplasm · Severe uncontrolled hypertension (SBP >185 mmHg) · Active internal bleeding (excluding menses) · Known bleeding diathesis
Relative	Recent major surgery (<10 days) · Recent major trauma · Pregnancy · Severe renal/hepatic impairment · Diabetic hemorrhagic retinopathy · Bacterial endocarditis · Recent CPR (>10 min)

Treatment Modalities

Modality	Mechanism	Duration	Best For
CDT (catheter-directed thrombolysis)	Continuous low-dose tPA infusion via multi-side-hole catheter embedded in clot	12–48h; ICU monitoring	Extensive iliofemoral thrombus; good lytic response
PCDT (pharmacomechanical CDT)	Mechanical maceration + simultaneous thrombolytic injection; devices: Angiojet, EkoSonic EKOS, Trerotola	4–24h; lower tPA dose	Preferred over CDT — shorter time, less tPA exposure (ATTRACT trial)
PMT (pure mechanical thrombectomy)	Aspiration without thrombolytics: Penumbra Indigo, ClotTriever	Single session; no lytic	Patients with absolute contraindication to lysis; acute DVT <14 days; high bleeding risk
Hybrid	CDT + mechanical + stenting	Variable	May-Thurner; refractory cases; extrinsic compression

Relevant Anatomy

The deep venous system of the lower extremity flows proximally: superficial femoral vein (misnomer — it IS a deep vein) → common femoral vein → external iliac vein → common iliac vein → IVC. Understanding this pathway is essential for catheter navigation and identifying thrombus extent.

May-Thurner anatomy: The left common iliac vein is compressed by the overlying right common iliac artery against the L5 vertebral body. This anatomic variant accounts for a 2–5× higher DVT incidence in the left leg compared to the right, and should be suspected in any young patient with left iliofemoral DVT.
Popliteal vein access: The primary approach for CDT (antegrade treatment toward the heart); patient positioned prone or lateral decubitus. US-guided puncture of the popliteal vein at or just above the popliteal fossa.
Internal jugular or femoral (antegrade) access: Alternative for high iliofemoral or IVC thrombus when popliteal access is not feasible or thrombus is limited to the iliac segment.
Dual-access technique: Popliteal + femoral puncture used for mechanical devices (e.g., ClotTriever) that require a through-and-through wire configuration for clot capture and extraction.

May-Thurner (iliac vein compression) syndrome: IVUS outperforms venography for diagnosing iliac vein compression — venography underestimates stenosis in approximately 30% of cases. After thrombus clearance, IVUS assessment of the left common iliac vein is mandatory before closing the case in any left-sided iliofemoral DVT.

Procedure Overview

The following is a high-level summary. Full catheter and device selection, tPA infusion protocols, venoplasty and stenting decision criteria, and IVUS interpretation are available in RadCall Pro.

Access: Popliteal vein puncture (US-guided, patient prone, 21G micropuncture) for antegrade clot traversal; 6–8 Fr sheath placed.
Venogram: Confirm extent of thrombus; identify proximal and distal extent; map anatomy to plan catheter course.
Wire and catheter across thrombus: Hydrophilic wire + directional catheter to traverse occlusion. Venous clot is soft — wire usually traverses easily without aggressive force.
CDT: Position multi-side-hole infusion catheter (5 Fr Unifuse or Cragg-McNamara) with working length spanning the thrombus. Infuse tPA 0.5–1 mg/hr + heparin 500 u/hr through side-arm of sheath. Monitor fibrinogen q6h; ICU admission mandatory during infusion.
PCDT/mechanical: EkoSonic EKOS (ultrasound-accelerated thrombolysis with reduced tPA dose); AngioJet (rheolytic thrombectomy); ClotTriever (large-bore aspiration). Follow device-specific protocol for each.
Check venogram at 12–24h: Reassess degree of lysis; reposition catheter or adjust infusion rate as needed.
Underlying stenosis evaluation: After thrombus clearance, perform IVUS to assess for May-Thurner compression or intrinsic iliac stenosis. Venoplasty + stenting (Venovo, Wallstent) if stenosis >50% or symptomatic.
Completion venogram: Confirm venous patency, no significant residual filling defect, and stent position if deployed.
Anticoagulation: Therapeutic anticoagulation (heparin infusion) maintained throughout procedure; transition to oral DOAC at time of sheath removal.

Complications

Complication	Rate	Management
Intracranial hemorrhage	<1% (CDT); rare (PCDT)	Immediate CT head; neurosurgery consultation; stop lysis immediately
Major bleeding (non-intracranial)	7–11% (CDT); ~4% (PCDT per ATTRACT)	Stop lysis; transfuse; FFP/cryoprecipitate if fibrinogen depleted; interventional hemostasis if source identified
Fibrinogen depletion	Common with CDT >24h	Hold tPA if fibrinogen <150 mg/dL; administer cryoprecipitate
PE during procedure	Rare (clot fragmentation)	Most clinically sub-clinical; IVC filter if deemed high risk prior to procedure; maintain anticoagulation
Access site hematoma	5–10%	Manual compression; rarely requires transfusion
DVT recurrence	20–30% at 5 years	DOAC for ≥3–6 months; indefinite if unprovoked; elastic compression stocking for 2 years

Post-Procedure Care and Follow-up

ICU admission during CDT infusion — mandatory: Neurological checks q2h; fibrinogen q6h; strict blood pressure control (SBP <180 mmHg throughout infusion).
Sheath removal: After fibrinogen normalizes and infusion is complete; hemostasis achieved via manual compression at popliteal access site.
Oral anticoagulation: Transition to rivaroxaban or apixaban (preferred per current guidelines for first-episode DVT); duration 3–6 months provoked, indefinite for unprovoked or recurrent DVT.
Compression stockings 30–40 mmHg: Fitted at 1–2 weeks post-procedure; worn continuously for 2 years — the single strongest evidence-based intervention for PTS prevention after any DVT.
Imaging follow-up: Duplex ultrasound at 1, 3, and 6 months post-procedure; CT venogram at 6 months if iliac stent was placed.
Stent surveillance: Duplex ultrasound at 1, 6, and 12 months after stent placement; therapeutic anticoagulation maintained while stent is in place.

Evidence Summary

Trial	Design / N	Key Findings
ATTRACT Trial (2017, NEJM)	RCT; n=692; PCDT + anticoagulation vs. anticoagulation alone for acute proximal DVT	Primary endpoint (PTS at 24 months by Villalta score): no significant difference (47% vs. 48%). Severe PTS (Villalta ≥10): 18% vs. 24% (p=0.04). PTS-related pain significantly reduced. Iliofemoral subgroup showed most benefit. Conclusion: PCDT reduces severe PTS and pain but not overall PTS rate.
CaVenT Trial (2012, Lancet)	RCT; CDT vs. anticoagulation; 2-year and 5-year follow-up	At 2 years, iliofemoral patency significantly higher with CDT (66% vs. 48%); PTS reduced (41% vs. 55%). Long-term benefit confirmed at 5-year follow-up with sustained patency advantage.
EKOS ULTIMA (2015)	Ultrasound-assisted CDT (related device data, primarily PE)	EKOS ultrasound acceleration reduces tPA dose requirement and procedure duration; supports use in PCDT protocols for DVT when thrombus burden warrants lytic therapy.
IVUS for May-Thurner	Multiple series	IVUS outperforms venography for iliac vein compression diagnosis — venography underestimates stenosis severity in ~30% of cases. IVUS-guided stenting associated with improved primary patency at 12 months.

Bottom line — patient selection is the key variable. Best candidates for catheter-directed DVT thrombectomy: young and active patients with iliofemoral DVT, acute onset <14 days, low bleeding risk, and high functional demand where PTS would significantly impair quality of life. The ATTRACT trial informs expectations: PCDT reduces the risk of severe PTS and pain, but shared decision-making should include realistic counseling that overall PTS rates may not differ from anticoagulation alone.

References

Vedantham S, et al. Pharmacomechanical Catheter-Directed Thrombolysis for Deep-Vein Thrombosis (ATTRACT). N Engl J Med. 2017;377:2240–2252.
Enden T, et al. Long-term outcome after additional catheter-directed thrombolysis versus standard treatment for acute iliofemoral deep-vein thrombosis (CaVenT). Lancet. 2012;379(9810):31–38.
Mewissen MW, et al. Catheter-directed thrombolysis for lower extremity deep venous thrombosis: report of a national multicenter registry. Radiology. 1999;211(1):39–49.
Laiho MK, et al. Preservation of venous valve function after catheter-directed and systemic thrombolysis for deep venous thrombosis. Eur J Vasc Endovasc Surg. 2004;28(4):391–396.
Stevens SM, et al. Antithrombotic Therapy for VTE Disease: Second Update of the CHEST Guideline. Chest. 2021;160(6):e545–e608.
Kearon C, et al. Antithrombotic Therapy for VTE Disease: CHEST Guideline and Expert Panel Report. Chest. 2016;149(2):315–352.
Forauer AR, et al. Intravascular ultrasound in the diagnosis and treatment of iliac vein compression (May-Thurner) syndrome. J Vasc Interv Radiol. 2002;13(5):523–527.

Full technique in RadCall Pro Complete catheter and device selection, tPA infusion protocols, IVUS interpretation, venoplasty and stenting criteria, and post-procedure anticoagulation management in RadCall Pro.

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Catheter-Directed DVT Thrombectomy