Illustration of measured values on the basis of echocardiographic views. A: Regions of interest (2×2 mm sample volume) placed at the RA, IAS, lateral LA and posterior LA studied at base and mid levels excluding the A-V-plane). B: time intervals measured in milliseconds: onset P-wave to start of atrial deformation (P to A’start), onset P-wave to peak of atrial deformation (P to A’peak) and onset P-wave to end of atrial deformation (total electromechanical activity, TEMA). Peak A-wave velocity measured in cm/s. C: Three-dimensional reconstruction of the atria, perspective from the apex towards the base of the heart (compare inset at lower left side). The white arrows indicate simplified atrial conduction pathways starting at the RA (figure’s left side), via the interatrial septum towards lateral LA (figure’s right side) and posterior LA (figure’s lower right side).