ABSTRACT
This chapter describes several rate of change measures in use, both invasive and noninvasive, and provides some data indicating Anrep and Bowditch validity in depicting the influence of sympathetic activity on contractile force (CF). Most of indirect indices utilize the rate at which some measureable cardiovascular parameter changes with respect to time. Although the index is feasible in the intact animal, its sensitivity appears to be lower than that of other indices. For example, Noble, Trenchard, and Guz examined the saliency of various rate of change measures as indices of CF and found that stroke power was less sensitive to pharmacological agents which increase contractility than other indirect indices. The noninvasive technique appears rather insensitive to CF changes. The noninvasive techniques most often suggested in the literature include the ballistocardiogram, the vibrophonocardiogram (VPC), finger plethysmography, and the use of externally-measured pulse waves from major arteries. The VPC is based on the external measurement of sound at the body's surface.
