Impact of stroke volume determination on pressure-volume relations measured by conductance catheter

Murine pressure-volume (PV) relations are typically obtained by using miniaturized conductance catheters, which measure instantaneous ventricular pressure and conductance signals, and then convert the measured conductance to volumes. However, the values of measured conductance are sensitive to many factors, such as catheter position and stroke volume (SV). Two conversion equations, classic Baan´s equation and nonlinear Wei´s equation, were used by performing in vivo rat experiments. The results showed that how to determine SV from measured pressure and conductance signals significantly affects the loop widths and shapes of the resulting pressure-volume relations. Two methods to determine SV are used and compared in this work to reveal its impacts on the resulting PV loops.