# Cardiogenic Shock > Cardiogenic shock for NEET-PG Medicine covers haemodynamic profile, SCAI staging, vasopressor and inotrope choice, mechanical support and revascularisation. - Canonical URL: https://prepelephant.com/topics/neet-pg/medicine/cardiogenic-shock - Exam / course: NEET-PG · Subject: Medicine - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-08 - Last updated: 2026-10-08 - Reference basis: Braunwald's Heart Disease; Harrison's Principles of Internal Medicine; ESC Guidelines on acute coronary syndromes - How to cite: "Cardiogenic Shock", PrepElephant, https://prepelephant.com/topics/neet-pg/medicine/cardiogenic-shock ## Direct answer Cardiogenic shock is inadequate tissue perfusion caused by primary cardiac pump failure, defined by systolic pressure below 90 mmHg or vasopressor need together with a cardiac index below 2.2 litres per minute per square metre and raised filling pressures. Acute myocardial infarction is the commonest cause, and survival depends on rapid revascularisation, perfusion-guided vasopressor and inotrope support, and an early decision about mechanical circulatory support. ## What you must remember - **Haemodynamics:** low cardiac output with high systemic vascular resistance and raised pulmonary capillary wedge pressure, the cold and wet profile of shock. - **SCAI staging:** stage A is at risk; stage B is beginning, with hypotension but no hypoperfusion; stage C is classic shock requiring intervention beyond fluids; stage D is deteriorating despite initial therapy; stage E is extremis with arrest. - **First-line vasopressor:** norepinephrine to maintain mean arterial pressure around 65 mmHg; vasopressin is added for refractory hypotension, and dopamine is an alternative. - **Inotropes:** dobutamine suits low output with adequate pressure; adrenaline is used when shock is refractory; milrinone adds vasodilation and hypotension risk. - **Avoid:** vasodilators in hypotension, and fluid boluses in pulmonary oedema, with right ventricular infarction as the principal exception because that ventricle is preload-dependent. - **Mechanical support:** intra-aortic balloon pump, microaxial flow pumps such as Impella, and veno-arterial ECMO for refractory shock; the IABP-SHOCK II trial showed no survival benefit from routine balloon counterpulsation. - **Revascularisation:** emergency PCI for the infarct-related artery; the SHOCK trial showed early revascularisation improved survival, and CULPRIT-SHOCK found culprit-only PCI superior to immediate multivessel PCI. ## A large anterior infarct with shock A 59-year-old diabetic man presents four hours after an anterior STEMI with blood pressure 78 over 50 mmHg, cold clammy skin, urine output of 15 mL/h and lactate of 5 mmol/L, with pulmonary oedema on examination. This is cardiogenic shock with hypoperfusion, SCAI stage C at least. 1. **Measure output:** An arterial line and echocardiography come first, to measure output and exclude mechanical complications such as ventricular septal rupture or papillary muscle rupture, which would change the surgical plan. 2. **Restore pressure:** Norepinephrine is started to restore pressure, and dobutamine is added if cardiac output remains low despite adequate filling. 3. **Give fluid with care:** Fluids are given cautiously, since the lungs are already congested, and vasodilators are withheld. 4. **Reperfuse the culprit:** Emergency angiography follows, and the culprit lesion is treated first, with staged revascularisation of the other vessels deferred in a patient this unstable. 5. **Escalate for stage D:** If the patient deteriorates into stage D, with worsening lactate and rising vasopressor needs, a percutaneous microaxial pump or venoarterial ECMO is considered at a centre able to offer it. 6. **Keep the principle:** Restoring flow to the infarct-related artery is the only definitive treatment, and everything else buys time. ## Where the exam tries to catch you Examiners set the same fluid, vasopressor and balloon-pump traps in every shock vignette. - **Trap:** giving a fluid bolus to a patient with pulmonary oedema — **Correct:** this is harmful, whereas in right ventricular infarction the same bolus is correct, because the right ventricle fails from lack of preload. - **Trap:** reaching for dopamine by habit — **Correct:** norepinephrine is the first-line agent in cardiogenic shock, with less arrhythmic risk. - **Trap:** using the intra-aortic balloon pump as routine therapy — **Correct:** the IABP-SHOCK II trial showed no mortality benefit, so it is no longer recommended as routine treatment. - **Trap:** waiting for mechanical support before reperfusion in a centre where it is scarce — **Correct:** in Indian centres the priority is the same as anywhere, to reperfuse the culprit artery quickly and transfer early rather than wait for further deterioration. ## Frequently asked questions ### What is the most common cause of cardiogenic shock? Acute myocardial infarction is the most common cause of cardiogenic shock, usually from left ventricular pump failure after a large infarct. Mechanical complications of infarction and advanced heart failure are other important causes. ### Which vasopressor is first-line in cardiogenic shock? Norepinephrine is the first-line vasopressor in cardiogenic shock, titrated to maintain mean arterial pressure around 65 mmHg. Vasopressin is added for refractory hypotension, and dopamine is an alternative where norepinephrine is unavailable. ### What does SCAI stage C signify in cardiogenic shock? SCAI stage C denotes classic cardiogenic shock, with hypoperfusion that requires intervention beyond fluids, such as a vasopressor or inotrope. It is the clinical point at which the patient needs a critical-care pathway and an urgent decision about reperfusion. ### Why is the intra-aortic balloon pump no longer used routinely in cardiogenic shock? The IABP-SHOCK II trial showed no survival benefit from routine intra-aortic balloon counterpulsation in cardiogenic shock complicating myocardial infarction. It is therefore reserved for selected patients rather than used as a standard part of treatment.