Biphasic changes in left ventricular function during hyperdynamic endotoxemia

Cardiac contractility was studied in a clinically relevant conscious swine model simulating human hemodynamics during endotoxemia. The slope of the en dsystolic pressure-volume relationship [end-systolic elastance (E-ES)] was used as a load-independent contractility index. Chronic instrumentation in 10 pigs included two pairs of endocardial ultrasonic crystals for measuring internal major and minor a;sial dimensions of the left ventricle, a microm anometer for left ventricular pressure measurement, and a thermodilution pu lmonary artery catheter. After a 10-day recovery period, control measuremen ts of cardiac hemodynamic function were obtained. The following week, Esche richia coil endotoxin (10 mu g.kg(-1).h(-1)) was administered intravenously for 24 h. E-ES increased 1 h after endotoxin infusion and decreased beyond 7 h. The later hemodynamic changes resembled human cardiovascular performa nce during endotoxemia more closely than the changes during the acute phase . E-ES decreased in the later phase. A similar biphasic response of E-ES ha s been reported during a tumor necrosis factor-alpha (TNF) challenge. Even though plasma TNF was highest at 1 h and declined thereafter in this study, no consistent relationship between TNF and E-ES was identified, and TNF le vels did not correlate directly with the changes in E-ES.