Mechanical Circulatory Support in Cardiogenic Shock

Authors, Journal, Affiliations, Type, DOI

• Jun Nakata, Takeshi Yamamoto, Keita Saku, Yuki Ikeda, Takashi Unoki, Kuniya Asai
• Journal of Intensive Care (2023) 11:64
• Nippon Medical School Hospital (Nakata, Yamamoto, Asai); National Cerebral and Cardiovascular Center Research (Saku); Kitasato University (Ikeda); Saiseikai Kumamoto Hospital (Unoki)
• Review article (open access)
• DOI: https://doi.org/10.1186/s40560-023-00710-2

Overview

This Japanese expert review covers the full tMCS spectrum for cardiogenic shock through a pressure-volume (PV) loop physiology framework. It provides detailed hemodynamic analyses of IABP, VA-ECMO, Impella, and ECPELLA (combined VA-ECMO + Impella), supported by simulation models and registry data. The paper presents a SCAI-based device selection/escalation protocol and structured weaning criteria. Three risk stratification tools for tMCS management are summarized: IABP Shock II, SAVE, and ENCOURAGE scores.

Keywords

Cardiogenic shock, mechanical circulatory support, IABP, VA-ECMO, Impella, ECPELLA, PV loop, SCAI classification, weaning, risk score, cardiac power output, pulmonary artery pulsatility index

Key Takeaways

Epidemiology

• 81% of CS patients have underlying ACS including AMI (CardShock registry)
• AMI-CS incidence: historically ~20% of AMI; declined to 7–10% in contemporary PCI era
• In-hospital mortality AMI-CS (Killip IV): 62.2% (1997) → 36.3% (2017) — Swiss AMI registry over 20 years
• Tokyo CV Care Unit Network: in-hospital mortality 38.5% (2007) → 27.2% (2016) in AMI-CS
• Japanese DPC database (n=160,559; 2010–2020): IABP-alone use fell 80.5% → 65.3%; Impella alone rose 0% → 5.0%; ECMO 19.5% → 29.6%

PV Loop Framework for tMCS

• PVA (pressure-volume area) bounded by ESPVR, EDPVR and pulsatile systolic PV curve — represents total mechanical energy and is linearly related to myocardial O2 consumption
• IABP: rapid deflation in systole decreases end-systolic pressure → modest SV increase; no direct diastolic LV effect; preserves coronary perfusion via diastolic augmentation
• VA-ECMO: retrograde arterial flow increases LV afterload → PV loop shifts rightward, PVA enlarges (worse O2 demand); venous return reduction does not compensate; adding IABP to VA-ECMO provides only limited leftward PV shift
• Impella partial support: LV still ejects; total CO and BP rise → LV end-systolic volume paradoxically increases; PVA not sufficiently reduced
• Impella total support: LV pressure never reaches BP; LV no longer ejects; PVA approaches zero — optimal unloading
• ECPELLA: reduces VA-ECMO-induced PVA increase while maintaining BP; adding vasodilator (SVR 1.2→0.5 mmHg·min/L) further markedly reduces PVA and increases total flow ("total unloading"); risk of LV suction if overly aggressive

IABP

• 7–8 Fr double-lumen catheter; balloon synchronized with ECG/pressure triggers; polyethylene balloon
• Increases diastolic BP, decreases afterload and myocardial O2 consumption, augments coronary artery perfusion, provides modest SV increase
• BCIS-1 (high-risk PCI, EF <30%): IABP reduced MACCE at discharge and mortality −34% at median 51 months
• CRISP AMI: IABP during primary PCI did not reduce infarct size in anterior STEMI without shock
• IABP-SHOCK II (2013): no 30-day mortality benefit in ACS-CS; no improvement at 6-year follow-up
• ESC 2014: downgraded IABP from Class I → Class III (not recommended) in ACS-CS
• JCS guidelines: Class I for mechanical complications of AMI; Class IIa for refractory ischemia post-reperfusion; Class III for routine CS use
• Complication rates (Kapur et al.): bleeding 12.9%, limb ischemia 1.5%, stroke 3.1% — most favorable safety profile among tMCS

VA-ECMO

• 17–24 Fr venous cannula + 14–19 Fr arterial cannula; membrane oxygenator + centrifugal pump
• Highest flow 3.0–7.0 L/min among all tMCS; oxygenates blood; most potent hemodynamic support
• SAVE-J trial: VA-ECMO as adjunct to CPR in cardiac arrest
• ESC: Class IIb for severe CS and in-hospital/out-of-hospital cardiac arrest
• JCS: Class IIa for drug-refractory CS; Class IIb for mechanical complications or bridge to surgery
• Key limitation: retrograde aortic flow increases LV afterload → PVA enlargement → increased myocardial O2 demand; Impella or IABP required to counteract
• Differential/regional hypoxemia: occurs when LV recovers and ejects deoxygenated pulmonary-venous blood; monitor right radial artery ABG and right upper torso SpO2 for cerebral hypoxemia
• Complication rates (Kapur): bleeding 28.2%, limb ischemia 14.3%, stroke 8.2% — highest among tMCS

Impella

• Axial flow Archimedes-screw pump; drains LV → pumps blood into ascending aorta
  • Impella 2.5: 12 Fr femoral, max 2.5 L/min
  • Impella CP: 14 Fr femoral, max 3.7 L/min
  • Impella 5.5: 21 Fr surgical cutdown (axillary or femoral), max 5.5 L/min — potential for longer-term support via axillary approach
• Reduces myocardial O2 consumption, improves MAP, reduces PAWP, reduces LV stroke work and wall stress
• Monitoring: pulsatile arterial signal = LV still ejects; non-pulsatile = well unloaded (or malpositioned → confirm with echo)
• Partial vs total support: only total support (LV no longer ejecting) achieves near-zero PVA; partial support increases LV end-systolic volume paradoxically
• USpella Registry: hemodynamic improvement in AMI-CS refractory to inotropes/IABP
• MACH II study: significant LVEF improvement at 3 years vs control in anterior STEMI patients treated with Impella 2.5
• J-PVAD registry: 30-day survival 80.9% with Impella alone in AMI Killip IV (vs 63.1% overall); LVEF 35% → 44.7% at explant (P<0.001)
• ISAR-SHOCK (n=25; 2008): CO improved significantly Impella 2.5 vs IABP (0.49 vs 0.11 L/min; P<0.05)
• IMPRESS trial (n=48; 2015): 5-year all-cause mortality Impella CP 46% vs IABP 50% — no significant difference
• Complication rates (Kapur): bleeding 27.7%, limb ischemia 4.2%, stroke 4.9% — intermediate profile
• Aortic regurgitation: may occur at Impella shaft/aortic valve gap — reduces LV unloading efficacy; appropriate volume and BP management required

ECPELLA (VA-ECMO + Impella)

• Combined use to maintain perfusion/oxygenation (VA-ECMO) and LV unloading (Impella)
• Schrage 2020 (n=255 ECMELLA vs 255 VA-ECMO; propensity-matched): 30-day mortality HR 0.79 (95% CI 0.63–0.98; P=0.03); sub-analysis: early Impella within 2h of ECMO HR 0.76 (P=0.03); late >2h HR 0.77 (P=0.22, NS)
• J-PVAD (ECPELLA; n=50 with LVEF data): mean LVEF improved 24.9% → 44.0% at Impella explant (P<0.001)
• Cappannoli meta-analysis vs VA-ECMO alone: bleeding RR 1.45, hemolysis RR 1.71, limb ischemia RR 1.43, RRT RR 1.54 (all P significant); infections RR 1.26 (NS)
• See concepts/ECPELLA for full detail

Monitoring for tMCS

• Basic: serial lactate, SVO2/ScVO2, urine output
• Advanced: arterial line, central venous catheter, daily TTE, PAC
• Pulse pressure/pulsatility: absent = severe contractile dysfunction; rising = heart recovery; ETCO2 also useful for recovery detection
• CPO = (MAP × CO) / 451 — strongest hemodynamic predictor of mortality (SHOCK trial)
• LV-dominant CS: PAWP or LVEDP >15 mmHg
• RV-dominant CS: RA pressure >15 mmHg + RA/PAWP ratio >0.63–0.86
• PAPi = (systolic PAP − diastolic PAP) / RA pressure; cutoff ≤0.9 in AMI-CS vs <1.85 for LVAD implantation

SCAI Classification and Device Selection Protocol

• Stage A–C: volume + IV inotropes; if LVEF <30% + LVEDP >20 mmHg persists → Impella; IABP preferred if goal is coronary perfusion augmentation (without LV unloading), high bleeding risk, or large-bore access problem
• Stage D–E (refractory CS, VT/VF, cardiac arrest requiring CPR): VA-ECMO first-line; add Impella or IABP if pulmonary congestion or insufficient aortic valve opening
• After tMCS initiation: early PCI revascularization if indicated (door-to-reperfusion <90 min); PAC placement before leaving catheterization laboratory
• CPO/lactate at 12–24h: CPO <0.6 W + lactate >4 mg/dL → device escalation; CPO >0.6 W + lactate <4 mg/dL → consider catecholamine/tMCS weaning

Weaning Protocol

• Three-step Impella/ECPELLA weaning:
  1. End-organ: improved BP + lactate normalization + off pressors + improved RA pressure/PAWP
  2. RV assessment: RA pressure <15 mmHg AND PAPi ≥1.0 → VA-ECMO weaning; minimum flow 1.5 L/min (range 1–2 L/min)
  3. LV assessment: PAWP <20 mmHg AND CPO ≥0.6 W → Impella weaning; minimum P-level 2
• Pulse pressure must reappear spontaneously before initiating weaning
• LVOT-VTI increase on echo = LV recovery indicator and Impella weaning criterion
• Significant MR at weaning (high PAWP/low CPO): evaluate severity; consider surgical/TEER repair before decannulation
• Criteria not met at any step → do not proceed; consider escalation or intensified HF therapy

Risk Scores for tMCS Management

• Authors acknowledge none of these scores incorporate SCAI staging or new Impella parameters

Shock Team and Regional Network

• Tehrani 2019: shock team protocol reduced in-hospital mortality 40% → 28%
• National Cardiogenic Shock Initiative (2016–2019; 35 US centers): in-hospital mortality 28% — favorable vs SHOCK trial (53%), IABP-SHOCK II (60%), CULPRIT-SHOCK (49%)
• Tokyo CV Care Unit Network: ~40% of hospitals Impella-certified; authors call for dedicated CS network with transfer protocols
• Guidelines recommend MCS-capable hub hospitals + spoke centers with defined protocols for early recognition, treatment, and transfer

Limitations of the Document

• Review article — no original prospective data
• Published November 2023; predates DanGer Shock RCT (2024) and 4-trial VA-ECMO IPD meta-analysis
• ECPELLA evidence is primarily observational (Schrage 2020: propensity-matched, not RCT)
• Japanese-centric perspective and registry data; guideline citations are JCS + ESC 2014/2016 (pre-2025 ACC guidance)
• Risk scores (IABP Shock II/SAVE/ENCOURAGE) acknowledged by authors as incomplete — exclude SCAI staging and new device parameters

Key Concepts Mentioned

• concepts/Temporary-Mechanical-Circulatory-Support — device selection, escalation, weaning protocols
• concepts/Cardiogenic-Shock — epidemiology, management framework
• concepts/SCAI-Shock-Classification — staging and device selection protocol
• concepts/ECPELLA — combined VA-ECMO + Impella approach

Key Entities Mentioned

• None requiring new entity pages

Wiki Pages Updated

• Created: wiki/sources/mcs-jic-2023.md
• Created: wiki/concepts/ECPELLA.md
• Updated: wiki/concepts/Temporary-Mechanical-Circulatory-Support.md (source_count 4→5)
• Updated: wiki/concepts/Cardiogenic-Shock.md (source_count 3→4)
• Updated: wiki/concepts/SCAI-Shock-Classification.md (source_count 2→3)
• Updated: wiki/sourceindex.md
• Updated: wiki/wikiindex.md