Which of the following best describes the primary pathophysiological mechanism in cardiogenic shock?

Explanation

## Cardiogenic Shock: Pathophysiology **Key Point:** Cardiogenic shock is characterized by **pump failure** — the heart cannot generate sufficient cardiac output to maintain adequate tissue perfusion, despite elevated left ventricular filling pressures (pulmonary edema). ### Mechanism The fundamental defect is **reduced ejection fraction** (EF typically <30%) due to: - Acute myocardial infarction (most common cause) - Acute decompensated heart failure - Myocarditis, arrhythmias, or mechanical complications (papillary muscle rupture, VSD) ### Hemodynamic Profile | Parameter | Cardiogenic Shock | | --- | --- | | Cardiac Output | ↓ (< 2.2 L/min/m²) | | Systemic Vascular Resistance | ↑ (compensatory) | | Pulmonary Capillary Wedge Pressure | ↑ (> 18 mmHg) | | Urine Output | ↓ | | Lactate | ↑ | **High-Yield:** The **elevated filling pressures** (pulmonary edema, elevated JVP) distinguish cardiogenic shock from hypovolemic shock, where filling pressures are low. ### Clinical Pearl Patients present with **cold and wet** signs: cool extremities (poor perfusion), pulmonary crackles (pulmonary edema), and hypotension — a combination that mandates urgent echo and invasive hemodynamic monitoring. [cite:Robbins 10e Ch 4]