Non-invasive quantification of pressure-volume loops from cardiovascular magnetic resonance at rest and during dobutamine stress.

Abstract

Non-invasive quantification of pressure-volume (PV) loops from brachial pressure and cardiovascular magnetic resonance is a validated method but its application has been limited to resting heart rates. The aim of this study was to improve the previous method and validate it against invasive left-ventricular pressure measurements in an experimental porcine model, and further apply it to 16healthy humans at rest and during dobutamine stress. In addition, the improved method calculates the arterial elastance which provides the computation of the ratio of effective arterial (Ea ) to maximal ventricular elastance (Emax ) representing the ventricular-arterial coupling. In the porcine model, the differences between the improved non-invasively derived PV loops and invasively measured PV loops were for stroke work (mean±SD) 0.00±0.03J, ventricular efficiency -1.1±0.4%, and contractility 1.1±0.1mmHg/ml. In human subjects during dobutamine stress, stroke work increased from 1.3±0.3 to 1.7±0.4J, ventricular efficiency from 71±4 to 82±4%, contractility from 1.3±0.2 to 2.3±0.6mmHg/ml, and the ratio of arterial to ventricular elastance decreased from 0.96 to 0.56. The improved method for non-invasive PV loops constitutes a more robust diagnostic tool for cardiac disease states in a wider range of study cohorts at both rest and during stress.