Several important relationships can be derived from these signals. Specifically, a parameter
called the “End-Systolic Pressure-Volume Relationship” (ESPVR) describes the line of best
fit through the peak-ratio (maximum pressure with respect to minimum volume) coordinates
from a series of pressure-volume loops generated under varying loading conditions. The slope of this line has been shown to be a sensitive index of myocardial contractility that is
independent of loading conditions. In addition, several other analyses, including timevarying
elastance (Emax) and stroke work, are calculated. Time-varying elastance is
measured by determining the maximum slope of a regression line through a series of
isochronic pressure-volume coordinates. Stroke work is calculated by quantifying the area
of each pressure-volume loop. Statistical parameters are also calculated and displayed for
each set of data. Figure 136-28 illustrates the pressure-dimension loops and each of the calculated
parameters along with the various analysis options. Finally, the user has the ability
to export data sets into spreadsheet and database files, and to export graphs and indicators
into third-party-presentation software packages, such as Microsoft PowerPoint