Hyperspace analysis of left ventricular function

The canonical variables required to fully characterize ventricular function are its pressure (P) and volume (V), and their derivatives dP/dt, dV/dt. The 4-dimensional hyperspace spanned by P, V, dP/dt, dV/dt allows analysis of the left ventricular dynamics and has been a source for discovery of novel physiologic relationships. In this study we assess the physiologic information contained in the dP/dt vs. V plane of physiologic hyperspace. Using normal and diabetic murine P-V data, we characterize the maximum dP/dt (dP/dt_max) vs. end-diastolic volume (V_ed) and minimum dP/dt (dP/dt_min) vs. end-systolic volume (V_es) relationship. We observed that both dP/dt_max and dP/dt_min are highly linearly correlated with V_ed and V_es respectively (r² = 0.94, r² = 0.91). To fully elucidate this relationship an analog kinematic mathematical model was employed. Modeling results indicate that the observed linear dP/dt_min vs.V_es relation reflects the maximal rate of stiffness decrease, whereas the observed linear dP/dt_min vs. V_ed relation reflects the maximal rate of stiffness increase. We conclude that hyperspace analysis of ventricular hemodynamics facilitates discovery/characterization of novel physiologic relationships.