Echocardiographic examination
ECG guided, standard two-dimensional transthoracic echocardiographic studies were performed using available equipments VIVID 7 (General Electric Company) and IE33 (Philips Company) instruments, with 1.5-4.0 MHz transducer, according to a predetermined protocol recommended by American Society of Echocardiography and European Association of Cardiovascular Imaging (EACVI) (3,6,7).
All studies were done with patients lying in the left lateral decubitus position and breathing quietly. M-mode, 2D (frame rates .50–70 fps), colour Doppler, PW Doppler, pulsed-wave tissue Doppler, and PW and TDI (frame rates≥110 s-1) data were obtained in all patients. PW Doppler was obtained at the left and right ventricle outflow tract and continuous wave Doppler at the aortic and pulmonary valve. Transmitral flow pattern with E and A wave velocities was obtained with the sample volume positioned at mitral leaflet tips. PW TDI was obtained at the septal and lateral annular ring of the mitral valve, measuring s′, e′and a′ peak velocities . PW TDI was also obtained at the lateral tricuspid annulus in the four chamber view. Left atrium (LA) volume was measured from standard apical 4-chamber views at end-systole just before mitral valve opening. Left atrial volume index (LAVi) was calculated by dividing LA volume by body surface area of subjects.
All Doppler echocardiographic images were recorded in a digital raw-data format (native DICOM format), centralized and sent to core laboratory. The images were evaluated by three experienced echocardiographers blinded to any patient data.