Two-Dimensional, M-mode, and Doppler Acquisition Technique
Windows, modes, and measurement conventions
Acquisition items test whether you know which window answers which question. Parasternal long axis: LV dimensions, aortic root, valve morphology, pericardial effusion, and the LVOT diameter. Parasternal short axis at aortic, mitral, and papillary levels: leaflet motion, segmental wall motion, LV geometry. Apical four, two, three, and five chamber: all four valves by Doppler, LV volumes, LVOT flow. Subcostal: effusion, IVC, interatrial septum. Suprasternal: arch and descending aorta.
M-mode offers excellent axial and temporal resolution but samples a single line, so it cannot assess lateral structures - never grade a structure that drifts off the cursor.
Doppler rules: angle correct only when the cursor cannot be aligned with flow; use PW for localized low-velocity flow and CW for high velocities (gradients above roughly 2 m/s alias on PW); place the LVOT sample volume 0.5–1 cm proximal to the aortic valve in the apical five-chamber view; measure the LVOT diameter inner-edge to inner-edge in mid-systole in a zoomed long axis. Tissue Doppler uses low-velocity, high-amplitude filter settings to record septal and lateral e′.
Traps: measuring LVOT diameter from the apical view, using the apical three-chamber for aortic gradients, planimetering a heavily calcified aortic valve, and forgetting that color Doppler scale changes alter apparent jet area.
Rule of thumb: a diameter comes from 2D, a velocity comes from Doppler, and any velocity above 2 m/s needs continuous wave.