Myocardial dysfunction in sepsis.

The characteristic hemodynamic profile of human septic shock consists of a normal or elevated cardiac index and a decreased systemic vascular resistance index. When a patient with septic shock has a low cardiac index, concomitant hypovolemia is usually present. Within 48 hours of the onset of septic shock, most patients develop marked dilatation of both ventricles, depressed ejection fractions, and alterations of the Frank-Starling and diastolic pressure-volume relationships; stroke volume typically is well maintained. In surviving patients, cardiac function returns to normal within 10 days. An identical sequence of hemodynamic abnormalities occurs in an experimental canine model of sepsis that employs intraperitoneal implantation of infected fibrin clots. This myocardial dysfunction is not due to global myocardial ischemia; instead, there appear to be one or more circulating myocardial depressant substances. The chemical nature of these circulation mediators is under intensive investigation clinically, in vitro, and in the canine model.