Micro-axial LV Pumps (Impella) — Rapid Summary

Scope & Setup

  • Speaker/role: HF cardiologist & MCS medical director; focus on left-ventricular micro-axial flow pumps(Impella).

  • Context: Cardiogenic shock (CS) spiral → early Shock Team activation; temporary MCS early (before multiorgan failure); always define an exit strategy (recovery, LVAD/Tx, or palliation).

Hemodynamics & Candidate Selection

  • Pure LV CS profile: Narrow pulse pressure, ↓MAP/CO, cardiac power output (CPO) <0.6.

  • RV check: PAPi <0.9 suggests RV dysfunction; Impella favored when CPO <0.6 and PAPi ≥1 (preferably >2).

Device & Mechanism

  • Retrograde LV unloading: Catheter across aortic valve; drains LV → ejects to ascending aorta → ↓LVEDP, ↓pulmonary edema, ↑coronary and systemic perfusion.

  • Models: Impella CP (percutaneous, ~4.3 L/min, 14F sheath/9F pump); Impella 5.5 (surgical axillary, up to ~6.2 L/min).

Indications

  • Cardiogenic shock (primary),

  • High-risk PCI (LV dysfunction/left main),

  • ECpella/ELLA: LV unloading on VA-ECMO.

Evidence (from the lecture)

  • Cardiogenic shock (AMI/STEMI-predominant): DANger Shock trial—Impella + SOC ↓all-cause death vs SOC.

  • Guidelines (ACS 2025): In selected STEMI with severe/refractory CS, Impella is reasonable (not class I due to single RCT and ↑adverse events).

  • Observational data: Versus VA-ECMO—lower in-hospital mortality; long-term similar; outcomes hinge on exit strategy.

  • High-risk PCI: PROTECT II—no ITT advantage vs IABP; per-protocol signal only; pooled data not strongly supportive.

  • Impella 5.5 series/registries: Feasible for CS; allows bridging to LVAD/Tx; some myocardial recovery; safe beyond 14 days in experienced centers.

Contraindications

  • Mechanical AVR, LV thrombus, aortic dissection, severe PAD (access), severe AR; AS relative (wireable). Inability to anticoagulate problematic, especially during implant.

Implantation, Monitoring, Troubleshooting

  • Cath lab + fluoro/echo; confirm >3.5 cm LV depth; secure line.

  • Daily checks: CXR for position; labs for hemolysis (LDH, haptoglobin, bilirubin, Hb); limb perfusion.

  • Console alarms:

    • Diastolic suction: consider hypovolemia/RV failure/too deep → reduce speed, optimize filling, reposition.

    • Too shallow: LV pressure tracing pattern + high current → advance device.

  • Anticoagulation/purge: D5W purge (no saline); heparin if able; bicarbonate purge if heparin-intolerant; goal = prevent pump thrombosis.

Adverse Events (recognize/manage)

  • Bleeding, vascular injury/limb ischemia, stroke, hemolysis, device migration, pump thrombosis; risk varies with expertise and sheath size/duration.

Weaning & De-escalation (algorithmic)

  • Preconditions: resolving insult, improving organs, moderate vasoactive support, MAP ≥65, wedge ≤18, lactate <2, urine OK, LVOT-VTI >10, LVEF >~25%.

  • Stepwise speed reductions (P-levels) with reassessment; failure → consider LVAD/Tx.

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