Comparative measurements of left-ventricular performance produced by rapid changes in blood volume in dogs.

Abstract

Left-ventricular function was evaluated in 11 open-chest dogs under pentobarbital anesthesia. Ventricular performance was altered by infusing or withdrawing crossmatched blood, and simultaneous recordings obtained of left-atrial pressure, leftventricular pressure, aortic flow, and aortic pressure. From these recording were obtained the stroke volume, stroke work, peak ventricular power, and the maximal rate of change of aortic flow and ventricular pressure. The derived variables were plotted versus end diastolic pressure to provide ventricular-function curves. The curves were obtained during a control state, during norepinephrine infusion, and subsequent to aortic constriction at the level of the coronary ostia. Studies were done in the heart-rate paced and nonpaced animal; the data were presented in terms of per cent change from control values. Peak power and stroke work provided the more classical type of ventricular-function curves and it is suggested that these provide the most useful information. Pressure-derivative curves were the most widely separated. Similar studies were repeated in seven animals in which afterload was controlled at 100 mm Hg. Curve shape was somewhat altered but overall changes were comparable.