Planimetry of the left atrium for volume calculation from the apical 4 chamber view

An end-systolic freeze-frame image from the four chamber view is used to obtain maximum left atrial (LA) volume; panel A is a schematic of the structures imaged and panel B is the actual echocardiogram. The lines shown within the LA in panel C were generated by a light pen digitizing system that allows calculation of a single plane (area-length) volume from the outline shown or the combination of this area-length outline to calculate atrial volume by a modified Simpson's rule or method of discs.