Atrial Electromechanical Time Measurement
TDI was performed using transducer frequencies of 3.5–4.0 MHz. The spectral pulsed Doppler signal filters were adjusted until a Nyquist limit of 15–20 cm/s was obtained. The minimal opti mal gain was used. Myocardial TDI velocities [peak systolic (S’), early diastolic (E’) and late diastolic velocities (A’)] were measured with spectral pulsed Doppler from the apical 4-chamber view. The ultrasound beam slope did not exceed 15% to acquire the optimal angle of imaging. The monitor sweep speed was adjusted at 50–100 mm/s to optimize the spectral display of myocardial velocities. Atrial EMD was defined as the time interval from the onset of atrial electrical activity (P wave on surface ECG) to the beginning of mechanical atrial contraction (late diastolic A wave). All values were averaged over 3 consecutive beats. Atrial EMD was measured from the lateral mitral annulus and called ‘PA lateral’, from the septal mitral annulus, called ‘PA septal’, and from the right ventricle tricuspid annulus, called ‘PA tricuspid’. Inter-atrial EMD was calculated as the difference between PA lateral and PA tricuspid, intra-atrial EMD was calculated as the difference between PA septum and PA tricuspid, and left-atrial EMD was calculated as the difference between PA lateral and PA septum (5 ).
A total of 20 participants, 10 from the patient group and 10 from the control group, were randomly selected to evaluate the intra-observational variability. Measurements were repeated under the same baseline conditions. Intra-observer variability was 4% for lateral PA, 4.4% for septal PA, and 5.1% for tricuspid PA, respectively.