14.3 Peripheral Thrombectomy & Thrombolysis

Peripheral Thrombectomy and Thrombolysis

Peripheral thrombectomy and thrombolysis align with Domain C Task 11 on the RCIS outline — mechanical and pharmacologic strategies to treat acute limb ischemia, deep vein thrombosis (DVT), and pulmonary embolism (PE) when anticoagulation alone is insufficient. These emergent procedures demand rapid device preparation, strict activating clotting time (ACT) or activated partial thromboplastin time (aPTT) monitoring during lysis, and vigilance for bleeding complications. The RCIS is often the first team member to prepare thrombectomy systems when acute limb ischemia presents to the cath lab.

Acute Limb Ischemia: Assessment and Urgency

Acute limb ischemia (ALI) results from sudden reduction in limb perfusion threatening viability. The Rutherford classification guides urgency:

Etiologies include embolism (atrial fibrillation, valvular disease — sudden onset, minimal collaterals), thrombosis in situ (underlying PAD — gradual onset, existing collaterals), and graft thrombosis. Angiography defines occlusion level, runoff, and clot burden before selecting mechanical thrombectomy, thrombolysis, or surgical bypass.

Mechanical Thrombectomy Devices

Mechanical thrombectomy physically removes thrombus — faster than lysis alone for ALI Category IIb. The RCIS must prepare, flush, and troubleshoot each platform.

Rheolytic thrombectomy (AngioJet) uses high-pressure saline jets directed backward to create a Venturi effect that macerates and aspirates thrombus through a dedicated catheter. Operates at ~10,000 psi pump pressure. Requires large-bore sheath (6–8 Fr), activation with saline purge to remove air, and bradycardia monitoring — the AngioJet causes vagally mediated bradycardia during operation in some patients (atropine at bedside). Contraindicated in heavily calcified vessels and used cautiously in single runoff vessel (risk of losing all downstream perfusion if debris embolizes). Hemolysis from red cell destruction can cause hyperkalemia and hemoglobinuria — hydrate and monitor labs.

Aspiration thrombectomy (Indigo, Penumbra, Export) uses large-lumen catheters connected to continuous vacuum (Indigo Lightning 12 system, Penumbra CAT8) to directly aspirate clot. Lower hemolysis risk than rheolytic systems. Indigo catheters range from CAT3 to CAT12 (3–12 Fr aspiration lumens) — larger catheters for iliofemoral clot, smaller for tibial. The RCIS connects aspiration pump tubing, verifies canister placement, and monitors for blood loss in the collection canister.

Rotational thrombectomy (Arrow-Trerotola PTD) uses a rotating basket to macerate clot in dialysis grafts and native vessels — niche application compared with AngioJet and aspiration platforms.

Catheter-Directed Thrombolysis (CDT)

Catheter-directed thrombolysis infuses thrombolytic agent (recombinant tissue plasminogen activator — rt-PA/alteplase) directly into thrombus via a multi-sidehole infusion catheter (Cragg-McNamara, UniFuse, Osiris). Lysis occurs over 12–48 hours in the intensive care setting — unlike single-session mechanical thrombectomy.

Indications include acute DVT with iliofemoral involvement (phlegmasia cerulea dolens), submassive PE, ALl Category IIa where gradual lysis preserves runoff assessment, and graft thrombosis with sensitive distal vessels.

Dosing protocols vary by institution; common alteplase regimens use 0.5–1 mg/hr through the infusion catheter with low-dose heparin drip (300–500 units/hr) to prevent catheter thrombosis. The RCIS role during CDT includes:

1. Catheter placement verification — confirm sideholes within thrombus on fluoroscopy
2. Infusion pump setup — program rt-PA and heparin rates per order
3. aPTT/ACT monitoring per protocol (typically q6h)
4. Neurovascular checks — pulse, capillary refill, compartment assessment q1–4h
5. Bleeding surveillance — groin oozing, hematuria, intracranial hemorrhage signs

Contraindications to thrombolysis: recent stroke (<3 months), active internal bleeding, recent major surgery (<10–14 days), severe uncontrolled hypertension, intracranial pathology. The RCIS verifies consent, labs (CBC, fibrinogen, aPTT, creatinine), and type-and-screen before lysis begins.

Complications: major bleeding (2–10%), distal embolization, compartment syndrome after reperfusion, and allergic reaction to rt-PA. Fibrinogen levels <100 mg/dL during lysis signal high bleeding risk — notify the operator.

Combined Mechanical and Pharmacologic Strategies

Contemporary practice often combines mechanical thrombectomy followed by adjunctive CDT (pharmacomechanical thrombolysis) to reduce total lytic dose and procedure time. AngioJet Power Pulse spray delivers pulse-sprayed rt-PA into clot before rheolyytic aspiration — the RCIS prepares both lytic syringe and AngioJet pump per protocol.

For massive and submassive PE, catheter-directed therapy (CDT or ultrasound-accelerated thrombolysis with EkoSonic) delivers lytic directly to pulmonary arteries when systemic thrombolysis is contraindicated or failed. The RCIS prepares multisidehole pigtail or dedicated PE catheters, connects infusion pumps, and monitors hemodynamics (right heart strain, blood pressure support).

Deep Vein Thrombosis Interventions

Iliofemoral DVT with severe symptoms or phlegmasia benefits from early clot removal to prevent post-thrombotic syndrome (PTS). IVUS in the iliac veins identifies May-Thurner syndrome (left common iliac vein compression by the right common iliac artery) — stenting the iliac vein after thrombectomy/lysis prevents rethrombosis.

Venous thrombectomy uses the same aspiration and rheolytic platforms as arterial ALI, adapted for larger venous lumens. Venous stenting (Wallstent, Zilver Vena, Abre) requires self-expanding large-diameter stents sized to reference vein diameter with adequate inflow and outflow.

The RCIS distinguishes arterial vs venous cases for anticoagulation management: venous interventions typically continue therapeutic anticoagulation (heparin drip transitioning to DOAC or warfarin) throughout and after the procedure.

Reperfusion Syndrome and Post-Procedure Care

Reperfusion syndrome after successful thrombectomy/lysis causes acidosis, hyperkalemia, myoglobinuria, and compartment syndrome from ischemic muscle washout. The RCIS monitors for rising potassium, dark urine, and increasing calf circumference. Fasciotomy trays should be available for Category IIb cases with prolonged ischemia (>6 hours).

Access-site hemostasis after thrombectomy is complicated by post-procedure anticoagulation — manual compression times extend, or closure devices are used with strict post-deployment monitoring. Document distal pulses before and after sheath removal.

Exam Focus Points

RCIS exam items on thrombectomy/thrombolysis test: Rutherford Category IIb urgency, AngioJet bradycardia risk, CDT infusion setup and aPTT monitoring, contraindications to lysis, and combined pharmacomechanical approaches. Vignettes often present ALI with absent pedal Doppler and sensory loss — requiring emergency mechanical thrombectomy rather than elective lysis alone. PE scenarios may test catheter-directed rt-PA when systemic lysis is contraindicated.