Cardiogenic Shock

Overview
  • Cardiogenic Shock is shock induced by intrinsic failure of myocardial pump activity in the setting of adequate venous return. Although Hypovolemic Shock may also reduce myocardial pumping due to reduced venous return and thus preload, this is not considered an "intrinsic" defect of the heart pump.
Pathogenesis
  • Cardiogenic Shock is initiated by a significant myocardial insult which significantly deranges myocardial function. In most cases the proximate insult is a myocardial infarction but can also be due to hypertrophic cardiomyopathy, myocarditis, aortic stenosis, or arrhythmias. This manifests as a reduction in myocardial contractility and thus ejection fraction which reduces cardiac output. Reduced cardiac output leads to decreased perfusion of cardiac tissue which consequently exacerbates the original infarction. Sadly, a vicious cycle ensues in which further myocardial insults lead to further reductions in cardiac output which exacerbate hypoperfusion, thus adding to the myocardial insult.