16.1 Mechanical, Pharmacologic & Aspiration Thrombectomy

Mechanical, Pharmacologic & Aspiration Thrombectomy

ARRT Cardiac-Interventional Procedures 2.A.5 is thrombectomy — mechanical, pharmacologic, and aspiration — in coronary and selected peripheral work. The same interventional Focus of Questions used throughout 2.A applies: anatomy and pathophysiology, indications, contraindications, imaging, access, ultrasound, equipment, complications, and closure. Balloon angioplasty cracks plaque (15.1). A stent scaffolds it (15.2). Atherectomy modifies calcium (15.3). This section is about clot: how it occupies a lumen, how you extract or lyse it, and how fragments become no-reflow instead of TIMI 3.

Quick Answer: Rheolytic (AngioJet-class) thrombectomy uses high-velocity saline jets and a Venturi vacuum; hemolysis releases adenosine that causes bradyarrhythmia, so have pacing standby, especially in the right coronary artery (RCA). Catheter-directed lytics (intracoronary bolus or infusion catheters) are this chapter; systemic alteplase and tenecteplase — intracranial hemorrhage (ICH), recent stroke, recent surgery — already live in 5.1. Manual aspiration (Export-class) and large-bore suction treat visible STEMI or saphenous-vein-graft (SVG) thrombus; they are selective, not a mandatory every-STEMI step. Distal embolization and no-reflow are the shared complication family.

Anatomy and pathophysiology

Coronary thrombus is platelet-fibrin on a ruptured cap, in a dissected lumen, or in an ectatic, stagnant, or aneurysmal segment. ST-elevation myocardial infarction (STEMI) and some non-STEMI angiograms show a large filling defect. SVGs are a classic high-burden bed: old, friable, wide, and ready to shower the native distal vessel. Peripheral arterial thrombus (iliac, superficial femoral, popliteal) and selected venous thrombus obey the same physics with larger lumens and different French sizes.

The harm is twofold. The clot occludes the epicardial (or peripheral) conduit. Fragments embolize into the microcirculation. That second injury is no-reflow — TIMI 0–1 despite an open conduit — which 14.2 treats with intracoronary vasodilators. Thrombectomy exists to reduce burden before a balloon or stent mash-spreads it. Atherectomy (15.3) is calcium modification, not a thrombus-first device; do not reach for a rotational burr because the filling defect looked dark.

Indications and contraindications

Indications (teaching): large, angiographically visible thrombus in STEMI or SVG PCI; selected acute limb or bypass-graft occlusion; catheter-directed lysis when the operator chooses infusion over extraction; bailout after a balloon that produced slow flow because thrombus was underestimated.

Contraindications and cautions:

• Do not treat routine STEMI without visible thrombus as a mandatory aspiration case — selective use, not automatic.
• Rheolytic systems: a vessel too small for the catheter, an unsecured dissection, or an RCA/SVG run without pacing and atropine ready.
• Catheter-directed or intracoronary lytic: the same ICH cluster as 5.1 — recent stroke, recent major surgery or trauma, active bleeding, known intracranial mass, uncontrolled hypertension. Point to 5.1 for systemic-lytic pharmacology; this section is where the drug is delivered.
• Aspiration: a catheter oversized for the vessel, a dry syringe that injects air, or chasing a tiny filling defect until you dissect the wall.
• Inability to anticoagulate as the planned extraction or infusion requires.

Imaging, access, and ultrasound

Imaging. Cine angiography shows the filling defect, TIMI flow, and whether dye hangs in an SVG. Re-image after thrombectomy before you declare success — residual thrombus is common. Intravascular ultrasound (IVUS) or optical coherence tomography (OCT) can separate residual clot from dissection, but do not make an OCT flush your first move through a huge thrombus. Fluoroscopy watches aspiration-catheter markers and any distal embolic-protection filter if the operator deploys one. Distal protection is expanded in 17.2; know the concept here for SVG work and for fragments you do not want to lose downstream.

Access. Coronary thrombectomy travels through the same radial or femoral guiding catheter used for PCI, with enough lumen for the aspiration or rheolytic catheter plus a wire. Large-bore peripheral and venous systems need larger femoral sheaths. If an infusion catheter will dwell overnight, plan a sheath you can leave and a closure strategy that is not a same-hour pull.

Ultrasound. Vascular ultrasound guides the arterial or venous stick and later diagnoses hematoma, pseudoaneurysm, or occlusion. It does not grade coronary thrombus. After large-bore femoral venous work, ultrasound the groin the same way you would after any device case.

Equipment: three families

Mechanical — rheolytic (AngioJet-class). High-pressure saline jets create a Venturi / Bernoulli vacuum that fragments thrombus and carries it into the effluent. Hemolysis is expected. Free adenosine from lysed red cells causes bradycardia, atrioventricular block, and hypotension, especially when the catheter runs in the RCA or a graft that dumps into a right-sided bed. Temporary pacing standby — pads already on, plus a balloon-tipped or temporary-wire plan — is the exam-stable safety step. Hemoglobinuria can follow. Do not treat the pause as “vagal from the groin” if it starts the moment the jets fire.

Mechanical — stent-retriever and peripheral mechanical. Neurovascular-style stent retrievers and peripheral mechanical systems capture or macerate clot and pull it into a sheath. They appear more in peripheral arterial and selected large-vessel work than as everyday coronary tools. Distal embolization and vessel trauma are the risks. Know they live on the ARRT mechanical list. Do not confuse a stent retriever with a coronary drug-eluting stent (15.2).

Pharmacologic — catheter-directed. Intracoronary lytic (alteplase or tenecteplase in operator-directed small doses) is local fibrinolysis for heavy thrombus or no-reflow with residual clot. Infusion catheters (side-hole or ultrasound-assisted platforms) dwell in a thrombosed artery, graft, or vein and deliver lytic over hours. This is not a 100 mg systemic STEMI drip. Systemic lytics, ICH risk, and recent-stroke / recent-surgery contraindications are already in 5.1. Confirm the order and the concentration. Every extra puncture is now a hemorrhage site.

Aspiration — manual Export-class and large-bore. A hollow catheter, a lockable syringe, and continuous suction while you withdraw. Keep the syringe in suction; a disconnected hub is an air-embolism setup (6.3). Large-bore aspiration (coronary CAT-class, peripheral vacuum systems, selected venous circuits) moves more volume and needs a larger guide or sheath. Empty the canister, watch blood loss, and never inject the syringe back into the coronary.

Complications, SVG, no-reflow, and closure

Shared complications: distal embolization, no-reflow, dissection, perforation, air from a dry aspiration line, access hematoma after a large sheath, and — for rheolytic work — bradyarrhythmia and hemolysis. SVG PCI is the teaching storm: bulky thrombus, a degenerated wall, and a native distal bed that cannot tolerate a shower. If the operator uses a distal-protection filter, have it on the table and do not collapse a basket full of debris without an aspiration plan.

Closure is the same craft as after PCI: radial band or femoral manual compression / vascular closure device when the stick is suitable. After overnight catheter-directed lysis the puncture is a bleeding puncture — document ACT or fibrinogen per protocol, hold longer, and do not yank a sheath because the coronary looks pretty. Ultrasound that guided access also finds the hematoma.

Worked case

A degenerated SVG to the RCA is occluded with a large filling defect in STEMI. The team reaches for a rheolytic catheter. Confirm pacing pads and atropine before the first jet run — RCA/graft rheolytic work is adenosine-bradycardia territory. After extraction, TIMI 2 with a blushless distal bed is no-reflow, not an invitation to a bigger jet. Switch to intracoronary vasodilators and, if thrombus remains, selective aspiration. Do not fire a systemic tenecteplase dose “because it is a STEMI” if primary PCI is underway — that is 5.1 territory and ICH risk stacked on a freshly stuck groin.

Exam traps

• Rheolytic ≠ Export. Jets plus hemolysis plus RCA pacing standby.
• Systemic lytic contraindications live in 5.1; 2.A.5 is catheter-directed delivery.
• Routine STEMI aspiration is not automatic; visible thrombus / SVG is the teaching indication.
• Distal embolization and no-reflow are the complication pair, not proof the vessel is cured.
• A stent retriever is not a coronary DES.