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Tracing of the right atrium (RA) is performed from the plane of the tricuspid annulus (TA), along the interatrial septum (IAS), superior and anterolateral walls of the RA. The right atrial major dimension is represented by the green line from the TA center to the superior right atrial wall, and the right atrial minor dimension is represented by the blue line from the anterolateral wall to the IAS.