Linear Measure

The 3-chamber view is ideal for acquiring a linear measure—the left atrial dimension (cm)—of the size of the left atrium. This datum may be obtained at end systole, where the atrium is at its largest throughout the cardiac cycle, by drawing a single line that is perpendicular to the left atrial wall. This line should approximately bisect the chamber, although the line should be drawn through the largest region of the atrium.