Echo assessment includes:
- LA morphology.
- LA dimensions.
- LA function.
Morphology:
Overall size and shape of LA.
Identify any masses e.g. tumour or thrombus.
Spontaneous echo contrast – particularly in presence of AF/MS.
Left atrial appendage not easily seen on TTE but can sometimes be seen in A2C view.
Pulmonary veins can be seen on A4C – particularly right upper PV.
Core Triatriatum – rare congenital abnormality where the LA is partitioned into two chambers by a membrane – best seen in A4C.
Membrane normally contains one or more perforations allowing blood to flow between the two chambers.
Remains a degree of obstruction to LV inflow which can be assessed using PW doppler.
Cor Triatriatum dexter is the name given when it occurs in the right atrium.
Dimensions:
Causes of LA dilation:
- MV disease
- DCM
- RCM
- LV diastolic dysfunction
- AF/flutter
- High output states
- ‘Athlete’s heart’
LA diameter measured in end-systole in PLAX view.
LA volume measured using modified Simpson’s biplane. Trace endocardial border ignoring pulmonary veins that may be visible. Measure in both A4C and A2C.
Machine should calculate LA volume for you – if it doesn’t it can be calculated from:
Index for BSA.
LA volume index >34ml/m^2 (moderate dilation) has been shown to be an independent risk factor for death, ischaemic stroke, heart failure and atrial fibrillation.
Function:
Can be assessed but is tedious and not commonly performed.
Very dependent on loading conditions making interpretation difficult.
Pressure:
LA will enlarge as pressure increases due to compliance.
As LA pressure increases, EDT gets faster and E becomes more prominent (rapid diastolic filling).
Perform TDI at mitral annulus as for diastolic function.
E/e’ >15 (septal) represents raised atrial pressure (>20mmHg).
E/e’ <8 (septal) or <10 (lateral) is normal.