Left atrial function: pathophysiology, echocardiographic assessment, and clinical applications

This article describes the pathophysiology of left atrial mechanical function and discusses both conventional and new echocardiographic parameters used to evaluate left atrial function. The evidence regarding the clinical usefulness of left atrial function assessment is also presented. Atrial function, in a close interdependence with left ventricular (LV) function, plays a key role in maintaining an optimal cardiac performance. The left atrium (LA) modulates LV filling through its reservoir, conduit, and booster pump function, whereas LV function influences LA function throughout the cardiac cycle. The LA can act to increase LA pressure (in significant atrial disease) and can react to increased LV filling pressure (in significant ventricular disease). LA remodelling is related to LV remodellingw1 and LA function has a central role in maintaining optimal cardiac output despite impaired LV relaxation and reduced LV compliance.1 Understanding how each component of LA function is influenced by LV performance, and how each LA phasic function contributes to maintain an optimal stroke volume in normal and diseased hearts, is important for interpreting data derived from quantification of LA function. During LV systole and isovolumic relaxation, the LA functions as a reservoir, receiving blood from the pulmonary veins and storing energy in the form of pressure. This atrial function is modulated by LV contraction, through the descent of the LV base during systole, by right ventricular systolic pressure transmitted through the pulmonary circulation, and by LA properties (ie, relaxation and chamber stiffness).w2 During early …