Tricuspid annular dimensions measured at end-diastole in the modified apical four-chamber view to maximise right heart size. Right atrial (RA) major (vertical white line) dimension is from the centre of the tricuspid annulus to the centre of the superior RA wall, parallel to the atrial septum. The RA minor (horizontal white line) dimension is from the mid-level of the RA free wall to the septum, perpendicular to the long axis.