Measurement of right atrial parameters. Areas and diameters were measured in the phase of the cardiac cycle at which the atrial size was at a maximum. The figure shows the 2-chamber (top) and 4-chamber (bottom) views in which measurements were done. In B), longitudinal diameter (L) is obtained from the posterior wall of the right atrium to the center of the tricuspid plane, and transverse diameter (T) is obtained perpendicular to the longitudinal diameter, at the mid level of the right atrium. In C) measured areas are shown for both views.