Cardiogenic shock 

Definition: This is shock that results from severe depression of cardiac performance. It primarily results from pump failure [myocardial failure].

 *  Cardiogenic shock is hemodynamically defined as: 

-   DBP<60mm Hg 

-   Left ventricle filling pressure > 18mm Hg

-   Cardiac index< 1.8 l/min/m2

-   Usually pulmonary oedema coexists. 

 Causes of cardiogenic shock can be divided into:

   A. Myopathic

 B. Mechanical

A) Myopathic causes of cardiogenic shock include:

1.  Acute myocardial infraction. Usually shock occurs in this conditioin if ≥ 40% of the left ventricular mass & more on the right ventricle is involved by infarction. 

2. Mycocarditis 

3.  Dilated cardiomyopathy/hypertrophic cardiomyopathy

4.  Myocardial depression in septic shock

5. Etc….

B) Mechanical 

i) Intracardiac 

a) Left ventricle outflow obstruction E.g.Aortic stenosis, hypertrophic cardiomyopathy

b) Reduction in forward cardiac output E.g. Aortic or mitral regurgitation

c) Arrhythmia 

ii) Extracardiac 

This can be called obstructive shock. The extracardiac causes of cardiogenic shock can be caused by:

a)  Pericardial tamponade (gross fluid accumulation in the pericardial space) results in a

decreased ventricular diastolic filling → ↓CO

b)  Tension pneumothorax (gas accumulation in pleural space) 

This decreases the venous return by creating a positive pressure. 

c)  Acute massive pulumonary embolism occupying 50-60% of pulumonary vascular bed. 

d)  Severe pulumonary hypertension (10 pulmonary hypertension).  

References

Bezabeh ,M. ; Tesfaye,A.; Ergicho, B.; Erke, M.; Mengistu, S. and Bedane,A.; Desta, A.(2004). General Pathology. Jimma University, Gondar University Haramaya University, Dedub University.