Cardiovascular · Topic 11 of 48

Mechanical Circulatory Support (IABP, Impella, LVAD, ECMO)

Cardiovascular · mechanical support

Mechanical Circulatory Support (IABP, Impella, LVAD, ECMO)

IABP counterpulsates, Impella pumps LV to aorta, VA-ECMO replaces heart and lungs, and a durable LVAD runs without a pulse — each with its own failure modes.

Key numbers

IABP: inflate in diastole, deflate before systole~0.5 L/min added

LVAD: no pulse — Doppler MAP 70–90MAP 70–90 mmHg

01 · WhyIABP: inflate in diastole, deflate before systole

The IABP inflates at the dicrotic notch (onset of diastole) to raise coronary perfusion and deflates just before systole to cut afterload and oxygen demand; it adds only about 0.5 L/min of output.

02 · Don't confuseVV-ECMO for lungs, VA-ECMO for heart

VV-ECMO drains and returns venous blood to oxygenate in respiratory failure; VA-ECMO returns blood to the arterial system and supports both circulation and gas exchange in shock or arrest.

03 · WatchLVAD: no pulse — Doppler MAP 70–90

A continuous-flow LVAD often leaves no palpable pulse and unreliable cuff and pulse-oximetry readings; measure MAP by Doppler (first Korotkoff sound) or arterial line, targeting 70–90 mmHg.

What it is

Core idea

Impella pumps blood from LV to aorta must knowImpella is a microaxial pump placed retrograde across the aortic valve: it pulls blood from the LV into the ascending aorta, unloading the ventricle. Contraindications: LV thrombus and a mechanical aortic valve.

Diagnosis & monitoring

Work-up

IABP tip just below the left subclavianPosition the IABP tip about 2 cm below the left subclavian artery origin with the balloon above the renal arteries; confirm by daily chest radiograph. Losing the left radial pulse means too high.

Management

Orders

LVAD: warfarin to INR 2–3HeartMate 3 LVAD patients take warfarin to an INR of 2.0–3.0; ARIES-HM3 showed aspirin can be omitted, cutting bleeding without more thrombotic events.

LVAD arrest: compress if ETCO₂ < 20In an unresponsive, pulseless LVAD patient, start chest compressions if end-tidal CO₂ is below 20 mmHg (AHA 2017); a normal ETCO₂ suggests the pump is still perfusing.

Red flags & don'ts

Avoid harm

No IABP with aortic regurgitation or dissection avoidIABP contraindications: moderate-to-severe aortic regurgitation, aortic dissection, significant aortic aneurysm, severe peripheral arterial disease, severe bleeding disorder and uncontrolled sepsis.

VA-ECMO distends the LV — vent it complicationVA-ECMO returns blood retrograde into the aorta and raises LV afterload without unloading the ventricle, causing LV distension and pulmonary edema; vent with inotropes, an IABP, an Impella or septostomy.

IABP: check distal pulses and renal function complicationIABP complications include limb ischemia, insertion-site bleeding, aortic dissection, renal failure, bowel ischemia, stroke and infection; check distal pulses frequently, restrict hip flexion and follow hemoglobin, platelets and creatinine daily.

Impella: bleeding, limb ischemia, hemolysis complicationMicroaxial pumps cause more severe bleeding, limb ischemia, hemolysis and kidney injury needing dialysis; in DanGer Shock the safety composite occurred in 24% with the pump versus 6% without.

Peripheral VA-ECMO: check a right radial gas complicationWith femoral VA-ECMO and poor lung function, the heart can eject deoxygenated blood to the brain and arms (differential, North–South hypoxemia); draw arterial gases from the right arm to detect it.

LVAD GI bleeding: AVMs and acquired von Willebrand complicationBleeding is the most common LVAD complication — usually GI (often arteriovenous malformations) or epistaxis — driven by anticoagulation and acquired von Willebrand deficiency; reverse anticoagulation only with the VAD team.

Pump thrombosis: power spikes and hemolysis complicationSuspect LVAD pump thrombosis with high-power alarms, hemolysis (LDH over 2.5 times normal, plasma-free hemoglobin over 20 mg/dL, hemoglobinuria) and recurrent heart failure or shock.

Driveline infection is the commonest LVAD infection complicationThe driveline exit site is the most common LVAD infection, usually gram-positive cocci, presenting as cellulitis around the site; culture and start broad-spectrum antibiotics.

Suction events and RV failure after LVAD complicationAn underfilled LV (hypovolemia, RV failure, tamponade) lets the inflow cannula suck against the wall, dropping flow; give cautious fluid unless RV failure is the cause, when fluid worsens it.

The rules

Know these

Impella yes, routine IABP no, in MI shockIn MI-related shock, a microaxial pump is reasonable for selected STEMI patients (Class 2a; DanGer Shock), while routine IABP and routine VA-ECMO did not lower mortality (Class 3: No Benefit).

IABP or Impella?

Commonly confused

How it works	Balloon in descending aorta inflates in diastole, deflates before systole
Support	Minimal — about 0.5 L/min
Key contraindication	Moderate–severe aortic regurgitation, aortic dissection
MI-related shock evidence	Routine use: no mortality benefit (Class 3)
Main complications	Limb ischemia, bleeding, renal or bowel ischemia

More detail

Reference

Show 6 reference facts

Durable LVADs serve as bridge to transplant or as destination therapy for patients who are not transplant candidates; temporary devices bridge to recovery, decision or a durable device.

Anticoagulation targets: VA-ECMO heparin to ACT 180–210 seconds; Impella purge heparin to ACT 160–180 seconds; IABP heparin (aPTT 50–70) is optional.

With large-bore (≥ 12 French) arterial access, check distal pulses every 1–2 hours; limb ischemia doubles in-hospital mortality, and a distal perfusion cannula protects the leg on femoral VA-ECMO.

Wean temporary support stepwise — about 0.5–1 L/min every 2–4 hours — reassessing exam, perfusion labs, echo and hemodynamics at each step, as a daily interdisciplinary shock-team decision.

IABP benefit falls with tachycardia above 130/min and requires a cardiac index of at least 1.2–1.4 L/min/m²; check timing in 1:2 assist mode.

Stroke affects 13–30% of LVAD patients, peaking early after implant and at 9–12 months; infection and high MAP raise the risk.

Pearl

IABP inflates in diastole and deflates before systole; VA-ECMO raises afterload, so watch the left ventricle distend.

Sources · ACC Coronary Interventions Handbook, Ch. 11 — Overview, Indications, and Step-by-Step Techniques for Hemodynamic Support Devices · LITFL Critical Care Compendium — Intra-Aortic Balloon Pump · Hockstein MA. Continuous-flow left ventricular assist devices: management in the emergency department. JACEP Open 2020;1:362–370 · Cameli M et al. A multidisciplinary approach for the emergency care of patients with left ventricular assist devices: a practical guide. Front Cardiovasc Med 2022 · Sinha SS et al. 2025 Concise Clinical Guidance: ACC Expert Consensus Statement on the Evaluation and Management of Cardiogenic Shock. J Am Coll Cardiol 2025;85:1618–1641 · ACC Clinical Trial Summary — DanGer Shock (Microaxial Flow Pump in Infarct-Related Cardiogenic Shock) · Mehra MR et al. Aspirin and Hemocompatibility Events With a Left Ventricular Assist Device in Advanced Heart Failure (ARIES-HM3). JAMA 2023 · Merck Manual Professional — Chronic Heart Failure (device therapy) · ACC — Cardiogenic Shock and Mechanical Circulatory Support: Year in Review 2025 (2025 ACS guideline device classes) · ACC Clinical Trial Summary — ARIES-HM3 (aspirin vs placebo with VKA, INR goal 2.0–3.0) · Starter sheet built from the verified AGACNP fact map (facts reviewed 2026-10-15).