Analysis of left ventricular hemodynamics in physiological hyperspace

Abstract

10.1152/japplphysiol.00560. 2001.—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/d t) 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/d t, time derivative of V) hyperspace, we consider three-dimensional embedding diagrams having dP/d t, 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.