Evaluation of left ventricular function during ejection.

Several ejection indices of left ventricular performance are described. The most sensitive is the rate of change of power, especially when measured at the time of peak left ventricular wall tension. When measured at peak tension, the rate of change of power reflects force-velocity-length relations and, therefore, is theoretically appealing. The rate of change of power itself incorporates terms shown to be of functional significance. Among these is the rate of change of flow. This expression is more readily measured than the rate of change of power and can be approximated noninvasively by the measurement of blood acceleration.