Cardiogenic shock is primarily caused by which mechanism?

• A. Severe vasodilation and dehydration
• B. Low cardiac output due to reduced preload, high afterload, or poor myocardial contractility
• C. Bacterial sepsis causing vasodilation
• D. Airway obstruction

Answer: (B)

Cardiogenic shock arises when the heart cannot pump effectively enough to meet the body's needs, so the cardiac output falls and tissues are underperfused. The primary mechanism is low cardiac output caused by problems with the heart itself—most commonly poor myocardial contractility from damage or failure, but it can also be worsened by high afterload (the heart must push against increased resistance) or, in some cases, reduced preload (less blood available to be pumped). This combination directly links a failing pump to inadequate perfusion, which is the hallmark of cardiogenic shock.

The other scenarios involve shock where the heart’s pumping isn’t the main problem: widespread vasodilation with reduced circulating volume points to hypovolemic or distributive shock, sepsis causes vasodilation and maldistribution of blood flow, and airway obstruction leads to hypoxia rather than pump failure.