In vitro cardiac function in early sepsis

The involvement of the myocardium in the injury resulting from bacteremia has been somewhat controversial. Recently, some investigators have suggested that the transition from an early stage of sepsis, in which the cardiovascular system is stable and mortality is relatively low, to the late or preterminal stage of sepsis is a result of cardiac dysfunction. Here, however, data are presented to show that contractile defects and loss of myocardial reserve occur even early during a septic episode, i.e., at a time when cardiac output is elevated or normal. Efforts to determine the mechanism of the cardiac dysfunction are described. These entail studies of whole heart performance under conditions of varying the calcium availability for contraction and assessment of subcellular organelle function. The data indicate that calcium dyshomeostasis may at least partially contribute to the cardiac dysfunction of sepsis. The in vivo adequacy of cardiac function probably results from the capacity of the myocardium in early sepsis to respond to catecholamine support of chronotropy and inotropy.