Myocardial function in sepsis and endotoxin shock.

Myocardial function in sepsis and endotoxin shock is reviewed. Clinical, whole animal, and isolated tissue studies are compared to answer the question whether sepsis and/or endotoxin directly damage the myocardium. Myocardial performance is considered relative to control of preload, afterload, and heart rate. Despite the fact that these vary widely in different studies, there is overwhelming evidence that myocardial performance is depressed in both sepsis and endotoxin shock. The depression is dose related, occurs early after large doses of endotoxin but may follow a hyperdynamic phase in sepsis or after low doses of endotoxin. Endotoxin itself does not appear to be the depressant factor; the final depressant substance(s) is unknown. Calcium transport by the sarcoplasmic reticulum is depressed. This defect is more prominent in the endocardium than in the epicardium. Myocardial adenosinetriphosphatase (ATPase) and norepinephrine stores may be depleted. The septic myocardium has an increased dependence on sympathetic nerve stimulation. There is little evidence that the cause of the myocardial depression is an inadequate coronary blood flow.