Cardiogenic Shock: Causes, Hemodynamics & Treatment

Cardiogenic shock is the most severe form of heart failure — the heart can't pump enough blood to meet the body's needs. Here's what causes it, its hemodynamic signature, and how it's treated.

What is cardiogenic shock?

Cardiogenic shock is a state of inadequate tissue perfusion caused by the heart's failure to pump — a low cardiac output despite adequate filling. It carries a high mortality and is a true emergency. The most common cause is a large heart attack that damages a big portion of the left ventricle.

Causes

• Acute myocardial infarction — the leading cause (extensive LV damage)
• Mechanical complications of MI — acute mitral regurgitation, ventricular septal rupture, free-wall rupture
• Acute decompensated heart failure and end-stage cardiomyopathy
• Severe valve disease, myocarditis, and arrhythmias

The hemodynamic profile

On a pulmonary artery catheter, cardiogenic shock has a distinctive signature:

Measure	Cardiogenic shock
Cardiac index	Low (< 2.2 L/min/m²)
PCWP (filling pressure)	High
SVR	High (compensatory vasoconstriction)

Contrast this with the other shock types in our shock hemodynamics guide.

Presentation

Patients are hypotensive with signs of poor perfusion — cool, clammy skin, reduced urine output, and altered mental status — often with pulmonary congestion (breathlessness, crackles) from the high filling pressures.

Treatment

• Treat the cause — urgent revascularisation (primary PCI) for an MI is the single most important step.
• Inotropes and vasopressors — to support blood pressure and output.
• Mechanical circulatory support — the intra-aortic balloon pump or a percutaneous ventricular assist device.
• Supportive care — oxygenation, ventilation, and careful fluid management.

Key takeaways

• Cardiogenic shock is low output from pump failure, with high mortality.
• A large MI is the commonest cause.
• Hemodynamics: low cardiac index, high PCWP, high SVR.
• Emergency revascularisation is the key treatment; support with inotropes and mechanical devices.

Frequently asked questions

What is cardiogenic shock?

A life-threatening state where the heart cannot pump enough blood to meet the body's needs, producing a low cardiac output despite adequate filling pressures.

What causes cardiogenic shock?

Most often a large myocardial infarction; also mechanical complications of MI, decompensated heart failure, severe valve disease, myocarditis, and arrhythmias.

What is the hemodynamic profile of cardiogenic shock?

A low cardiac index (under 2.2 L/min/m²), a high pulmonary capillary wedge pressure, and a high systemic vascular resistance.

How is cardiogenic shock treated?

Urgent revascularisation for an MI, inotropes and vasopressors, mechanical circulatory support such as an intra-aortic balloon pump, and supportive care.

Why does cardiogenic shock have a high mortality?

Because the failing pump can't sustain perfusion of vital organs, and it often follows extensive heart-muscle damage.