Does LD100 E coli shock cause myocardial failure?

Abstract

We have documented that myocardial dysfunction occurs in canine endotoxin shock and have designed this study to determine the effect of lethal live E coli-induced shock on the myocardium. Small adult heart "donor" dogs (wt range 6-9 kg) were infused with LD100 E coli (N = 12) or saline (N = 16) for 30 minutes. Two hours later, heart transfer surgery was initiated and once completed the isolated working left ventricle was allowed to equilibrate in the extracorporeal circuit of a "support" dog (wt range 22-32 kg). Myocardial performance was then evaluated by changing mean aortic pressure while controlling cardiac output. Three to five hours after E coli infusion, marked myocardial dysfunction occurred in 75% of the hearts as evidenced by increased left ventricular and diastolic pressures and depressed peak positive and negative dP/dt at every mean aortic pressure tested compared with control hearts. Myocardial efficiency and power were depressed, oxygen uptake was elevated, and coronary blood flow was unchanged in E coli-treated compared with control hearts. Data support the presence of heart dysfunction in gram-negative septic shock.