Pathophysiology and Therapy of the Shock of Myocardial Infarction

Cardiogenic shock results from a decrease in coronary blood flow that, by lowering the tension of myocardial oxygen and raising the concentration of myocardial depressant metabolites, reduces contractile strength and cardiac output. An effort should, therefore, be made to raise oxygen tension and decrease metabolite concentration. This can best be accomplished by improving coronary blood flow, but also useful are restoration of the normal arterial oxygen content and correction and prevention of increased oxygen use and metabolite production. When forced to use an agent that directly stimulates myocardial strength, it is important to select one that does not further aggravate the disproportion between oxygen delivery and use. An increase in strength at the expense of a further reduction in myocardial oxygen tension and a further increase in the concentration of myocardial depressant metabolites can only lead to a decreased chance of survival.