Ventricular-arterial coupling: Invasive and non-invasive assessment.

Interactions between the left ventricle (LV) and the arterial system, (ventricular-arterial coupling) are key determinants of cardiovascular function. Ventricularearterial coupling is most frequently assessed in the pressure-volume plane using the ratio of effective arterial elastance (EA) to LV end-systolic elastance (EES). EA (usually interpreted as a lumped index of arterial load) can be computed as end-systolic pressure/stroke volume, whereas EES (a load-independent measure of LV chamber systolic stiffness and contractility) is ideally assessed invasively using data from a family of pressure-volume loops obtained during an acute preload alteration. Single-beat methods have also been proposed, allowing for non-invasive estimations of EES using simple echocardiographic measurements. The EA/EES ratio is useful because it provides information regarding the operating mechanical efficiency and performance of the ventricular-arterial system. However, it should be recognized that analyses in the pressure-volume plane have several limitations and that "ventricular-arterial coupling" encompasses multiple physiologic aspects, many of which are not captured in the pressure-volume plane. Therefore, additional assessments provide important incremental physiologic information about the cardiovascular system and should be more widely used. In particular, it should be recognized that: (1) comprehensive analyses of arterial load are important because EA poorly characterizes pulsatile LV load and does not depend exclusively on arterial properties; (2) The systolic loading sequence, an important aspect of ventricular-arterial coupling, is neglected by pressure-volume analyses, and can profoundly impact LV function, remodeling and progression to heart failure. This brief review summarizes methods for the assessment of ventricular-arterial interactions, as discussed at the Artery 12 meeting (October 2012).