11.2 Cardiac Thrombectomy (Mechanical & Aspiration)
Key Takeaways
- TIMI thrombus grades 4–5 indicate large, obstructive thrombus and are primary triggers for selective aspiration thrombectomy; grades 0–3 range from absent to definite non-obstructive thrombus.
- Manual aspiration catheters (Export Advance, Pronto, Fetch) are advanced over a workhorse wire with 30–50 mL syringe suction; TASTE and TOTAL trials showed no mortality benefit with routine upfront aspiration in STEMI.
- The TOTAL trial demonstrated increased stroke risk with routine manual aspiration (0.7% vs 0.3%), shifting practice to selective use for large visible thrombus burden only.
- AngioJet rheolytic thrombectomy uses high-pressure saline jets (6000–8000 psi) creating Venturi-effect thrombus aspiration; each pass is limited to ≤30 seconds due to bradyarrhythmia and hemolysis risk.
- SVG PCI carries up to 30% no-reflow rates; thrombectomy combined with distal embolic protection is recommended when angiographic thrombus is present.
11.2 Cardiac Thrombectomy (Mechanical & Aspiration)
Intracoronary thrombus poses a major challenge during percutaneous coronary intervention, particularly in acute myocardial infarction, stent thrombosis, and degenerated saphenous vein grafts. Thrombus impedes guidewire passage, prevents stent apposition, and increases the risk of distal embolization, no-reflow, and periprocedural myocardial infarction. Cardiac thrombectomy devices remove thrombus mechanically or by aspiration before definitive stent deployment.
Angiographic Thrombus Assessment
Thrombus burden is graded using the TIMI thrombus grade:
| TIMI Thrombus Grade | Angiographic Description |
|---|---|
| Grade 0 | No cineangiographic evidence of thrombus |
| Grade 1 | Possible thrombus (intraluminal filling defect with free contrast on both sides) |
| Grade 2 | Definite thrombus with partial vessel outline visible |
| Grade 3 | Definite thrombus with vessel outline hidden in ≥2 views |
| Grade 4 | Large, mobile proximal thrombus |
| Grade 5 | Large, obstructive proximal thrombus with TIMI 0–1 flow |
Grades 4–5 represent high thrombus burden and are the primary angiographic triggers for selective thrombectomy. The RCIS documents thrombus grade before and after thrombectomy to assess device efficacy.
Manual Aspiration Thrombectomy
Manual aspiration thrombectomy is the most commonly used intracoronary thrombus removal technique. A dedicated aspiration catheter is advanced over a standard workhorse guidewire to the thrombus site, and negative pressure is applied via a large syringe to suction thrombus into the catheter lumen.
Device Examples and Specifications
| Device | Characteristics | Syringe Volume |
|---|---|---|
| Export Advance (Medtronic) | Single-lumen, soft-tipped aspiration catheter | 30 mL |
| Pronto (Medtronic) | Low-profile, trackable aspiration catheter | 30 mL |
| Fetch (Medtronic) | Aspiration catheter with enhanced trackability | 30 mL |
| Eliminate (Terumo) | Rapid-exchange aspiration catheter | 30–50 mL |
Aspiration Technique
- Wire placement: Advance a workhorse guidewire (BMW, Runthrough) distal to the thrombus into the target vessel.
- Catheter delivery: Track the aspiration catheter over the wire to the proximal edge of the thrombus under fluoroscopic guidance.
- Syringe connection: Attach a 30–50 mL syringe to the aspiration port. Some operators use a dedicated vacuum/sealed syringe system to maintain continuous negative pressure.
- Aspiration: Apply steady suction while advancing the catheter through the thrombus bed in a slow, controlled manner. Maintain suction while withdrawing the catheter to the guide catheter.
- Thrombus inspection: Examine aspirated material in the syringe and catheter lumen. Repeat passes may be necessary for large thrombus burdens.
- Angiographic reassessment: Inject contrast to evaluate TIMI flow grade, residual thrombus, and vessel diameter before proceeding to balloon angioplasty and stenting.
Evidence Base: TASTE and TOTAL Trials
The role of routine upfront aspiration thrombectomy in STEMI has been clarified by major randomized trials:
- TASTE trial (2013): Manual aspiration before PCI in STEMI showed no reduction in 30-day mortality, reinfarction, or stent thrombosis compared to PCI alone.
- TOTAL trial (2015): Routine manual aspiration before PCI in STEMI showed no mortality benefit and was associated with a significantly increased rate of stroke (0.7% vs 0.3%, p=0.02).
Current guidelines recommend selective, not routine, aspiration thrombectomy for STEMI. Reasonable indications include large angiographic thrombus burden (TIMI grades 4–5), visible thrombus preventing wire crossing or stent delivery, bailout for slow-flow during PCI, and saphenous vein graft intervention.
Rheolytic (Mechanical) Thrombectomy
Rheolytic thrombectomy uses high-pressure saline jets to create a localized low-pressure zone (Venturi effect) that macerates and aspirates thrombus simultaneously.
AngioJet System (Boston Scientific)
The AngioJet rheolytic thrombectomy system consists of a console delivering pressurized saline (typically 6000–8000 psi) through a multi-lumen catheter:
- Saline jets exit from the catheter tip at high velocity, directed backward into the catheter lumen.
- The Venturi effect creates negative pressure at the catheter tip, drawing thrombus into the catheter where it is fragmented by the jets.
- Debris and saline are aspirated through the catheter into a collection bag.
AngioJet catheter sizes for coronary use:
- XMI (1.4 mm): Small vessels, distal coronaries
- XVG (2.3 mm): Saphenous vein grafts, larger vessels
- Spiroflex (1.6 mm): Coronary arteries with moderate thrombus
AngioJet Technique and Precautions
- Setup: Connect the AngioJet catheter to the drive unit. Prime with heparinized saline. Verify jet function in a saline bowl before intravascular use.
- Crossing: Advance over a guidewire to the thrombus. The catheter must be activated (jets running) during advancement through thrombus.
- Pass duration: Limit each pass to ≤30 seconds to prevent hemolysis and bradyarrhythmias from adenosine release.
- Bradyarrhythmia: AngioJet causes transient bradycardia and asystole in up to 30% of cases due to adenosine and potassium release from hemolyzed red blood cells. Temporary pacing must be available.
- Hemolysis monitoring: Check serum potassium, free hemoglobin, and lactate dehydrogenase post-procedure. Hemoglobinuria may occur.
AngioJet is primarily used for saphenous vein graft thrombectomy, native coronary thrombus refractory to manual aspiration, and intraprocedural thrombus during complex PCI. It is less commonly used in primary STEMI due to the availability of simpler manual aspiration catheters and trial data showing no mortality benefit.
Thrombectomy in Special Clinical Scenarios
Saphenous Vein Graft (SVG) PCI
Degenerated SVGs carry the highest thrombus burden and no-reflow rates (up to 30%) of any PCI substrate. Thrombectomy before stenting is strongly recommended when angiographic thrombus is present. Combine thrombectomy with distal embolic protection (see Section 11.3) to capture debris and reduce periprocedural MI.
Stent Thrombosis
Acute and subacute stent thrombosis presents with large intraluminal thrombus surrounding a previously deployed stent. Aspiration thrombectomy clears the lumen to allow assessment of stent under-expansion, malapposition, or edge dissection. Avoid deploying a new stent directly into organized thrombus without prior thrombus removal.
Bailout Thrombectomy During PCI
If slow-flow or no-reflow develops during balloon inflation or stent deployment and angiography reveals new thrombus formation, bailout aspiration can restore TIMI flow. Administer intracoronary vasodilators (adenosine, nitroprusside, verapamil) concurrently if microvascular dysfunction contributes to slow-flow.
RCIS Responsibilities During Thrombectomy
The RCIS plays a critical support role during thrombectomy procedures:
- Device preparation: Pre-flush aspiration catheters, connect syringes, prime AngioJet drive units, and verify negative pressure systems.
- Hemodynamic monitoring: Watch for bradyarrhythmias during AngioJet passes; ensure temporary pacing pads and wires are connected and tested.
- Thrombus documentation: Record pre- and post-thrombectomy TIMI flow and thrombus grades in the procedural log.
- Specimen handling: Label aspirated thrombus specimens if sent for histopathology or embolic analysis.
- Post-procedure labs: Order post-procedure complete blood count, potassium, and free hemoglobin when rheolytic thrombectomy is performed.
Based on the TOTAL trial findings, what is the current recommended approach to manual aspiration thrombectomy in primary PCI for STEMI?
During AngioJet rheolytic thrombectomy, the operator must limit each thrombectomy pass to 30 seconds or less. What is the primary physiological reason for this time restriction?
A patient with a degenerated saphenous vein graft to the right coronary artery presents for PCI with TIMI thrombus grade 5 and TIMI flow grade 1. Which combination of interventions is most appropriate before stent deployment?