A 62-year-old man presents with crushing chest pain and BP 78/50 mmHg. Echocardiography shows an anterior wall motion abnormality with left ventricular ejection fraction 25%. Pulmonary artery catheter values are: cardiac index 1.7 L/min/m2, PCWP 24 mmHg, SVR 1800 dyn.s/cm5. Which category of shock do these haemodynamic values define?

• A Cardiogenic shock ✓
• B Distributive (septic) shock
• C Hypovolaemic shock
• D Obstructive shock from cardiac tamponade

Explanation

Cardiogenic shock is defined by a cardiac index below 2.2 L/min/m2 with elevated filling pressures (PCWP above 18 mmHg) and compensatory peripheral vasoconstriction raising the SVR. Septic shock shows a low SVR with high cardiac output, and hypovolaemic shock shows low CI with low PCWP, so both are excluded by the wedge pressure here. Tamponade would give equalisation of diastolic pressures rather than this isolated LV failure pattern.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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