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Indications & Contraindications
Massive PE (High-Risk) — Immediate CDT/Mechanical
- Hemodynamic instability (any one): SBP <90 mmHg for >15 min; OR requiring inotropic support; OR cardiac arrest/pulselessness; OR HR <40 bpm
- Cardiac arrest or impending arrest from PE
- RV failure on echo (RV/LV ratio >1.0, McConnell sign, severe TR)
- Indication for immediate CDT/large-bore mechanical thrombectomy OR surgical embolectomy
Submassive PE (Intermediate-High Risk)
- Echo or CT evidence of RV dysfunction (RV/LV ≥0.9 on CTA or echo) AND troponin elevation
- Hemodynamically stable but deteriorating on anticoagulation
- Failed systemic anticoagulation (recurrent PE, worsening RV strain)
- Absolute contraindication to systemic thrombolysis (recent surgery, stroke, GI bleed) — favors catheter-directed approach
- Saddle/central PE with bilateral main pulmonary artery involvement
PE Severity Stratification
- Massive PE: hemodynamic instability (SBP <90 or shock) — mortality 30–60%
- Submassive (intermediate-high risk): stable hemodynamics + RV dysfunction + troponin elevation — mortality 5–15%
- Low-risk PE: no RV dysfunction, no troponin elevation — anticoagulation only
Treatment Selection
- Low-risk: anticoagulation alone — no catheter intervention
- Submassive + lysis CI or high bleed risk: CDT (EKOS preferred) — ~10–20% of systemic dose, far lower ICH risk; PEITHO trial: systemic tPA cut decompensation 5.6%→2.6% but ICH rose 0.2%→2.4%
- Submassive + low bleed risk: CDT vs systemic tPA (PERT team decision); CDT preferred if procedural setup readily available
- Massive + no lysis CI: systemic tPA 100 mg/2h fastest option; CDT if patient already in IR or systemic tPA fails
- Massive + lysis CI (recent surgery, stroke, active bleed): large-bore mechanical thrombectomy (FlowTriever) — no lytics required
- Massive + refractory shock: VA-ECMO as bridge → surgical embolectomy or catheter-based debulking
Contraindications to Lysis
- Active internal bleeding, recent CVA (<2 months), intracranial neoplasm/AVM/aneurysm
- Major surgery/trauma <10 days (relative; catheter-directed carries lower systemic bleed risk than full-dose systemic)
PERT team discussion required for all borderline cases.
Major PE Trial Summary
| Trial | Design | Key Finding | Take-Home |
|---|---|---|---|
| PEITHO Meyer 2014, NEJM |
Submassive PE: systemic tPA vs placebo (all anticoagulated) | Death or hemodynamic collapse: 5.6% → 2.6% (tPA). ICH: 0.2% → 2.4% (tPA). | Systemic lysis cuts decompensation but ICH rises 12×. CDT preferred to reduce ICH risk. |
| ULTIMA Kucher 2014, Circulation |
Intermediate PE: EKOS CDT vs anticoagulation alone (24 patients each) | RV/LV ratio: CDT reduced 0.30 vs 0.03 at 24h. No ICH in CDT group. | EKOS CDT rapidly reverses RV dilation with very low bleeding compared to systemic lysis. |
| SEATTLE II Piazza 2015, JACC-CI |
Single-arm: EKOS for massive/submassive PE (n=150) | RV/LV ratio reduced 25% at 48h. PA pressure reduced 30%. ICH: 1 patient (0.7%). | Establishes CDT safety and efficacy benchmark; basis for widespread EKOS adoption. |
| EXTRACT-PE Sista 2021, Circulation |
Single-arm: Inari FlowTriever (large-bore aspiration) for massive/submassive PE (n=119) | RV/LV ratio reduced from 1.53 to 1.15 (25%) at 48h. Major adverse events: 1.7%. No thrombolytics used. | Mechanical thrombectomy without lysis viable for massive PE with absolute lysis contraindication. |
| FLARE Tu 2019, JACC-CI |
Single-arm: FlowTriever 20 Fr aspiration system (n=106) | RV/LV ratio reduced from 1.34 to 1.05 at 48h. Clinical success 95.5%. | Confirmed FlowTriever safety profile; supports large-bore mechanical thrombectomy as lysis-free option. |
| HI-PEITHO Ongoing |
Submassive PE: EKOS CDT vs systemic anticoagulation alone (RCT) | Results pending. | Will be definitive RCT for CDT in intermediate-risk PE. |
PE Management Decision Flowchart
| Confirmed PE (CTA or high clinical probability) | ||
| ↓ | ||
| Anticoagulation (UFH bolus 80 u/kg + 18 u/kg/h) — start immediately unless absolute CI | ||
| ↓ Risk Stratify | ||
| Low Risk No RV dysfunction No troponin elevation |
Submassive (Int-High) Stable + RV dysfunction + Troponin elevation |
Massive (High Risk) SBP <90 / shock Cardiac arrest |
| ↓ | ↓ PERT Activation | ↓ PERT + Emergent |
| Anticoagulation alone DOAC transition Outpatient if stable |
Lysis CI? → CDT (EKOS) No CI, lysis preferred → CDT or systemic tPA Deteriorating rapidly → Large-bore mechanical |
No lysis CI → Systemic tPA 100 mg/2h Lysis CI → Large-bore mechanical (FlowTriever/Inari) Refractory shock → VA-ECMO bridge |
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Pre-Procedure
PERT (PE Response Team) activation — multidisciplinary: IR, cardiology, cardiac surgery, critical care.
Stabilization: O2 to maintain SpO2 >90%; cautious fluid resuscitation (500–1000 mL, not large boluses which worsen RV dilation); vasopressors (norepinephrine or epinephrine) for refractory hypotension.
Anticoagulation: Start unfractionated heparin (80 units/kg bolus + 18 units/kg/h infusion) immediately if no absolute contraindication. Do NOT delay for imaging if clinical diagnosis is clear.
Echo: bedside TTE — RV/LV ratio, interventricular septal bowing (D-sign), TR, pericardial effusion.
CTA chest: if patient stable enough — confirms diagnosis, delineates thrombus location and extent, assesses bilateral PA involvement.
Labs: ABG, BMP, troponin, BNP/NT-proBNP, CBC, INR, type & screen.
ICU bed pre-arranged.
Consent obtained: ICH (1–2% with CDT, much lower than systemic lysis), access site bleeding, worsening hemodynamics during procedure, cardiac arrest during catheter placement.
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Relevant Anatomy
Right Heart & Pulmonary Arterial Anatomy
- Right ventricle → right ventricular outflow tract (RVOT) → pulmonary valve → main pulmonary artery → right PA → right upper/middle/lower lobe branches; left PA → left upper/lower
- Saddle embolus: thrombus spanning main pulmonary artery bifurcation — bilateral involvement
- Most effective thrombus location for CDT: main/lobar pulmonary arteries. Segmental and subsegmental PE: anticoagulation preferred.
Access & RV Fragility
- Venous access: right internal jugular vein (preferred) or right femoral vein. Avoid left femoral if IVC filter present.
- RV fragility: the hyper-distended RV during massive PE is extremely prone to decompensation from any further increase in preload or outflow resistance — all catheter manipulations must be gentle and deliberate.
- Avoid inducing arrhythmia in RVOT; use fluoroscopic guidance for all right heart catheter navigation.
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Technique
Supplies (CDT with EKOS)
Right IJV micropuncture access kit
8–9 Fr sheath
Multipurpose catheter + hydrophilic wire
Pigtail catheter (pulmonary angiography)
EKOS EkoSonic system (bilateral, 5.2 Fr, 12/24 cm active)
rtPA (alteplase) 1 mg/h per catheter
Pressure transducer + hemodynamic monitoring
ICU nursing at bedside throughout infusion
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Right IJV access
Micropuncture → 8 Fr sheath. Fluoroscopy throughout procedure.
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Right heart catheterization
Advance 5 Fr pigtail to main PA via right heart under fluoroscopy. Measure pulmonary artery pressure. Perform bilateral pulmonary angiogram. Document thrombus location.
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Wire into affected PA
Advance Glidewire into most affected PA (typically both right and left main/lobar PA for bilateral approach).
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Place EKOS catheters
One EKOS catheter per lung (bilateral approach standard for bilateral PE). Position 12 cm active element within main/lobar thrombus.
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Begin rtPA infusion
1 mg/h per catheter (2 mg/h total) + systemic UFH 500 units/h via peripheral IV (subtherapeutic). Monitor fibrinogen q6h. Hold lysis if fibrinogen <100 mg/dL.
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Check angiogram at 12–24h
Return to IR, assess thrombus burden. If good response: remove catheters. If inadequate: consider mechanical thrombectomy adjunct.
Large-Bore Mechanical Thrombectomy (FlowTriever/Inari EXTRACT-PE)
- Supplies: 24 Fr Inari EXTRACT-PE or FlowTriever 20/24 Fr system, right femoral vein access, stiff guidewire, 20 Fr sheath
- Step 1: Right femoral vein access — 6 Fr micropuncture → upsize to 20 Fr FlowTriever sheath
- Step 2: Navigate to main PA under fluoroscopy. Advance 20 Fr guide catheter.
- Step 3: Aspiration + retrieval — advance aspiration catheter into lobar PA. Deploy FlowTriever discs into thrombus. Withdraw under continuous aspiration. Multiple passes. Target main/lobar arteries.
- Step 4: Completion angiogram — confirm clot clearance. Assess PA pressure improvement.
Pulmonary Artery Catheterization — Technique & Troubleshooting
Navigating the right heart in massive PE requires specific attention to RV fragility. The hyper-distended, afterload-stressed RV is prone to arrhythmia and decompensation.
- Catheter choice: Grollman pigtail catheter (specifically designed for pulmonary angiography — 5 Fr, 8 cm pigtail radius, angled at the shaft) is the preferred catheter for both PA access and completion angiography. The large pigtail radius prevents RV entrapment. Alternative: standard pigtail 5 Fr for angiography only.
- Wire first approach: J-tipped guidewire advanced through the right heart into the RVOT under fluoroscopy, then catheter advanced over wire. Minimizes RV stimulation compared to catheter-first navigation.
- Float technique: For massive PE with very dilated RV, a balloon-tipped flotation catheter (Swan-Ganz type, 5 Fr) can be floated through the dilated RV into the PA with minimal manipulation — particularly useful when standard wire navigation fails.
- RV crossing: Advance catheter to IVC level. Enter right atrium. Rotate catheter anteriorly (clockwise from femoral, counterclockwise from IJV) to align with tricuspid valve. Advance wire into RV. Rotate further to direct wire into RVOT (pointing anteriorly and superiorly). Confirm fluoroscopically before advancing into PA.
- PA entry from IJV: From IJV approach, the catheter tends to enter the PA more directly — less RV manipulation. The Grollman catheter is specifically angled for the right IJV to main PA trajectory.
Troubleshooting Right Heart Navigation
- Wire loops in RV trabeculations: Use a J-wire (3 cm J-tip) to avoid catching trabeculations. Partial withdrawal and re-rotation often clears entanglement.
- Cannot pass tricuspid valve: Redirect wire anteriorly and inferiorly (the tricuspid orifice is anterior). An Amplatz left 1 or JR4 catheter can help angle toward the valve.
- Wire enters coronary sinus: Coronary sinus is posterior — redirect wire anteriorly to exit RV toward PA.
- Catheter won't advance past RVOT: If wire is in PA but catheter won't advance over it — try stiffer 0.035″ Amplatz-type wire; catheter loop in RV may need to be straightened by partially withdrawing.
- Hemodynamic collapse during manipulation: Stop immediately. Withdraw catheter to RA. Initiate vasopressors. Confirm position with fluoroscopy. Consider VA-ECMO if refractory.
CDT (EKOS Lysis) vs Large-Bore Mechanical Thrombectomy — Decision Guide
| Factor | CDT / EKOS | FlowTriever / Inari EXTRACT-PE |
|---|---|---|
| Thrombolytics | Required (rtPA 1 mg/h × 12–24h) | None — lysis-free |
| Lysis contraindication | Cannot use | Can use — ideal option |
| Speed of effect | 12–24h (slow, gradual) | Immediate (single-session clot removal) |
| ICH risk | ~1–1.5% (far lower than systemic lysis) | Negligible (no lytics) |
| Access size | 5–8 Fr (femoral or IJV) | 20–24 Fr (femoral — large bore) |
| Clot age | Acute clot required (<14 days) | Acute and subacute |
| ICU time | 24–48h (ongoing lysis monitoring) | May discharge next day |
| Best for | Submassive, bilateral clot burden, no lysis CI | Massive with shock, lysis CI, saddle embolus |
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Troubleshooting
Hemodynamic Instability During Catheter Placement
RV Decompensation or Arrhythmia
Stop catheter manipulation. Initiate vasopressors (norepinephrine). Avoid RVOT stimulation. Consider VA-ECMO (extracorporeal membrane oxygenation) support before proceeding if severe instability persists.
Cannot Navigate Wire into Pulmonary Artery
Wire Fails to Pass from RV into PA
Use stiffer catheter (Amplatz left, JR 4, or pigtail with gentle rotation). Consider J-wire to avoid entanglement with RV trabeculations. Balloon-tipped flotation catheter (Swan-Ganz type) can float through dilated RV into PA.
Fibrinogen Depletion During CDT
Systemic Fibrinogenolysis from rtPA
Hold lysis. Cryoprecipitate 10 units IV. Do not restart until fibrinogen >150 mg/dL. Consider that low fibrinogen signals effective lysis — may switch to anticoagulation alone if already substantial clot burden reduction.
No Improvement in RV Function at 12h
Inadequate Response to CDT
Consider organized/fibrotic thrombus (subacute/chronic), inadequate catheter positioning, or insufficient dose. Add mechanical thrombectomy (AngioJet, FlowTriever). If thrombus appears chronic: escalate to surgical embolectomy discussion with cardiac surgery.
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Complications
Immediate
- Cardiac arrhythmia (catheter manipulation in RV)
- Right heart perforation (rare)
- PA dissection
- Systemic embolization
Delayed
- ICH (~1–1.5% with catheter-directed, lower than systemic lysis)
- Access site bleeding
- CTEPH (chronic thromboembolic pulmonary hypertension) — baseline CTA at 3–6 months mandatory
- Recurrent PE without adequate anticoagulation
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Post-Procedure
ICU Monitoring
- ICU post-procedure: PA pressure monitoring if catheter in place, echo at 24–48h to assess RV improvement, pulse oximetry
- Serial troponins q6h for first 24h
- Fibrinogen q6h during CDT infusion
- Echo endpoints: normalization of RV/LV ratio, resolution of D-sign, reduction in TR
Anticoagulation & Follow-up
- Transition to therapeutic anticoagulation after catheters removed: LMWH bridge → rivaroxaban 15 mg BID × 21 days then 20 mg daily; or apixaban 10 mg BID × 7 days then 5 mg BID
- Duration: minimum 3 months; 6 months for unprovoked PE; indefinite for recurrent or malignancy-associated
- VTE follow-up clinic at 3 months
- CTA chest at 3–6 months: screen for CTEPH (incidence ~1–4% after acute PE)
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Critical Pearls
✦
PERT activation is the first step. Call the Pulmonary Embolism Response Team (cardiologist, cardiac surgeon, IR, critical care) for all massive and high-risk submassive PE. Multidisciplinary decision-making prevents premature escalation or missed escalation.
✦
Fluids can kill in massive PE. The failing RV is preload-sensitive and afterload-sensitive. Large IV fluid boluses (>1000 mL) distend an already dilated RV, worsen septal shift, and reduce LV filling → cardiovascular collapse. Give small boluses (250–500 mL) only.
✦
CDT for submassive uses 10–20% of the systemic dose. 1 mg/h via EKOS vs 100 mg systemic — dramatically lower ICH risk. This is why CDT is preferred when patient can tolerate procedural wait time.
✦
FlowTriever for massive with shock and lysis contraindication. Large-bore aspiration (FlowTriever, Inari EXTRACT-PE) allows rapid clot removal without thrombolytics — ideal for massive PE with absolute contraindication to thrombolytics (e.g., recent surgery).
✦
Check the RV on echo before and after. The therapeutic endpoint is RV recovery — not just clot burden reduction. Always obtain post-procedure TTE to document RV improvement. Persistent RV dilation suggests residual hemodynamic compromise.
✦
CTEPH is a long-term risk. Screen all submassive and massive PE survivors with CTA chest at 3–6 months. Refer for pulmonary hypertension evaluation if CTEPH suspected.
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References
Key Guidelines
- AHA/ACC/HFSA/HPNA/SCAI/STS PE Guidelines (2024) — Includes updated risk stratification, PERT activation criteria, and evidence-based algorithm for CDT vs mechanical thrombectomy. Key changes: PESI score integration, formal PERT recommendation (Class I), expansion of CDT indications for submassive PE with deterioration.
- ESC Acute PE Guidelines (2019) — risk stratification, hemodynamic definitions, sPESI scoring
- SIR Standards of Practice: PE (2018) — catheter-directed thrombolysis technique and dose standards
Primary References
- Piazza G, et al. A prospective, single-arm, multicenter trial of ultrasound-facilitated, catheter-directed, low-dose fibrinolysis for acute massive and submassive PE (SEATTLE II). JACC Cardiovasc Interv. 2015.
- Kucher N, et al. Randomized, controlled trial of ultrasound-assisted catheter-directed thrombolysis for acute intermediate-risk pulmonary embolism (ULTIMA). Circulation. 2014;129(4):479–486. PMID 24226805.
- Provias T, et al. The Pulmonary Embolism Response Team: initial 30-month experience with a multidisciplinary approach to massive and submassive pulmonary embolism. Hosp Pract (1995). 2014;42(1):31–37. PMID 24566594.
- Sista AK, et al. (EXTRACT-PE). Indigo aspiration system for treatment of pulmonary embolism. Circulation. 2021;143(22):2152–2163.
- Tu T, et al. (FLARE). Treatment of pulmonary embolism with FlowTriever aspiration catheter. JACC Cardiovasc Interv. 2019;12(9):859–869.
- Meyer G, et al. (PEITHO). Fibrinolysis for patients with intermediate-risk pulmonary embolism. N Engl J Med. 2014;370(15):1402–1411.