Left Atrium
Dimensions
Measured at end systole in PLAX using 2D or M-mode.
Can measure in A4C if PLAX not good enough.
Volume
Simpsons in A4C or A2C.
Pressure
Atrium will enlarge as pressure increases as it is compliant.
As LA pressure increases, EDT gets faster and E becomes more prominent (rapid diastolic filling).
TDI mitral annulus (as for diastolic function).
E (of mitral inflow) to Em (from TDI) ratio reflects LA pressure.
E/Em septal >15 = increased atrial pressure (>20mmHg), <8 normal, 8-15 grey area. Lateral is <10 or >10.