Changes in rabbit cardiac function during fulminant endotoxin shock.

Abstract

Septic shock in humans is usually characterized by severe changes in the left ventricular function, while little is known about the dysfunction of the right ventricle. Rabbits were injected intraventricularly with endotoxin from Escherichia coli at a dose of 2 mg/kg following catheterization of both heart ventricles with the purpose of measuring their pressure, and determining a number of contractility indices. In the animals in which endotoxin shock developed very rapidly and death occurred between the 60th and the 90th min (shock development is called fulminant), we established significant changes in the function of both ventricles. At the 20th min, the intraventricular pressure, EDP and P-(dP/dtmax) increased, indicating a tension lead of the right ventricle. At the same time, there was a decrease in plus dP/dtmax, minus dP/dtmax, (dP/dtmax)/P and [(dP/dt)/P]max, considered evidence for impaired contractility and relaxation of the right ventricular myocardium. During the subsequent observation periods, some of the contractility indices returned to normal. At the 20th min, a reduction of intraventricular pressure, P-(dP/dtmax), plus dP/dtmax, minus dP/dtmax and (dP/dt)P was registered in the left ventricle. Pronounced bradycardia was observed from the 30th min to the end of the experiments. Fulminant endotoxin shock in rabbits occurs as a result of the impaired function of the right ventricle attributed to tension leading and endotoxin-induced biventricular myocardial dysfunction.