When the Pump Fails: Cardiogenic Shock

• Defined by SBP <90 for ≥30 min with low cardiac output, elevated filling pressures, and hypoperfused organs (cool, mottled, oliguric).
• AMI causes most cases; emergent reperfusion (PCI) is the only intervention proven to cut mortality. ECG within 10 min.
• Support with noradrenaline for pressure and dobutamine for contractility; skip fluid boluses, and Impella CP is Class 2a in STEMI cardiogenic shock (DanGer Shock 2024); routine IABP is not recommended (IABP-SHOCK II) and routine VA-ECMO gave no benefit (ECLS-SHOCK 2023).
• Use Swan-Ganz when shock is uncertain or mixed; taper support once lactate clears and urine output recovers.

Mechanisms of Cardiogenic Shock

• Myocardial infarction
• Myocardial dysfunction, systolic and diastolic, plus systemic inflammation
• Systolic dysfunction: cardiac output ↓, stroke volume ↓ → decreased systemic perfusion and hypotension
• Diastolic dysfunction: LVEDP ↑ → pulmonary congestion → hypoxemia
• Hypotension → coronary perfusion pressure ↓; hypoxemia → myocardial ischemia
• Myocardial ischemia → worsening myocardial dysfunction → death
• Parallel inflammatory pathway: MI → systemic inflammation → inflammatory cytokines ↑ → iNOS ↑ → NO/peroxynitrite ↑ → vasodilatation, SVR ↓ → systemic perfusion falls further
• Systemic perfusion ↓ → compensatory vasoconstriction → afterload ↑ → progressive myocardial dysfunction (self-perpetuating cycle)

Managing Suspected Cardiogenic Shock

• Cardiogenic shock suspected: SBP <90 mm Hg plus low-output signs (oliguria, poor mental status, pulmonary edema)
• Immediate ECG first — look for AMI evidence (ST elevation, new LBBB, suspected posterior MI) — with rapid stabilization; supplemental O₂/mechanical ventilation for hypoxia
• BP support: norepinephrine first-line vasopressor (SOAP II: lower mortality/arrhythmia than dopamine); dopamine only for selected bradycardic patients · goal MAP ≥65 mm Hg · all vasopressor patients need intra-arterial pressure monitoring · Impella CP mechanical support is Class 2a in STEMI cardiogenic shock (DanGer Shock 2024)
• ECG positive (AMI evidence)?
• Reperfusion therapy immediately
• Pharmaco-invasive strategy (lysis, then early angiography) only when the cath lab is not immediately available — then transfer; routine IABP is NOT recommended (IABP-SHOCK II)
• Cardiac catheterization: emergent invasive evaluation once cardiogenic shock is recognized — no fixed hour cutoffs; routine VA-ECMO showed no benefit in AMI shock (ECLS-SHOCK 2023)
• Revascularization candidates: emergent CABG (3-vessel disease, left main disease, or PCI not possible) or PCI of the infarct artery with stenting; GP IIb/IIIa inhibitors (abciximab) for bailout only
• Emergent echocardiogram: evaluate LV/RV function; exclude mechanical CS complications — VSD, acute MR/papillary muscle rupture, free wall rupture, RV infarction
• PA catheter monitoring: cardiac etiology confirmed by CI <2.2 L/min/m², PCWP >15 mm Hg
• No revascularization possible: continue medical support; with stable BP consider inotropes — dobutamine 2.5–10 µg/kg/min, milrinone 0.375–0.75 µg/kg/min (avoid milrinone in hypotension, renal failure)
• Refractory shock: weigh LVAD, transplant evaluation