title: Analysis of left ventricular hemodynamics in physiological hyperspace.
abstract: Our laboratory has previously shown that it is possible to elucidate novel physiological relationships by analyzing the left ventricular pressure (P) contour in the phase [time derivative of P (dP/dt) vs. P] plane (Eucker SA, Lisauskas JB, Singh J, and Kovács SJ, J Appl Physiol 90: 2238-2244, 2001). To further characterize cardiac physiology, we introduce a method that combines P-volume (V) and phase plane-derived information in physiological hyperspace. From four-dimensional (P, V, dP/dt, time derivative of V) hyperspace, we consider three-dimensional embedding diagrams having dP/dt, P, and V as coordinate axes. Our method facilitates analysis of physiological function independent of inotropic state and permits assessment of P-V-based relationships in the phase plane and vice versa. To test feasibility, the method was applied to murine hemodynamic data. As predicted from first principles, the area of the P-V loop (ventricular external work) correlated closely (r = 0.97) with phase plane limit cycle area (external power). The P-V plane-derived linear (r = 0.99) end-systolic P-V relationship (maximum elastance) appeared linear in the phase plane (r = 0.85). We conclude that analysis of data in physiological hyperspace is generalizable: it facilitates quantitative characterization of ventricular systolic and diastolic function and can guide discovery of novel physiological relationships.
authors.affiliation: Cardiovascular Biophysics Laboratory, Washington University, St. Louis, Missouri 63110, USA.
authors.forename: Stephanie A
authors.initials: SA
authors.lastname: Eucker
authors.forename: Jennifer
authors.initials: J
authors.lastname: Lisauskas
authors.forename: Michael R
authors.initials: MR
authors.lastname: Courtois
authors.forename: Sándor J
authors.initials: SJ
authors.lastname: Kovács
mesh_terms: D000465:Algorithms; D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D006328:Cardiac Catheterization; D016014:Linear Models; D051379:Mice; D008954:Models, Biological; D017711:Nonlinear Dynamics; D016277:Ventricular Function, Left / Q000502:physiology*