2.4. Standard echo-Doppler study:
Standard echo-Doppler was performed using a Vivid E9 ultrasound system (GE Vingmed Ultrasound AS, Horten, Norway). Cine-loops were recorded on DVDs for offline analysis (EchoPAC PC 6.0.0, GE Medical Systems). All the measurements were analysed taking the average of three cardiac cycles. LV diameter and wall thickness were measured according to the criteria of the American Society of Echocardiography. (10)
Left atrium (LA) volume was determined by the biplane-area-length method.(11) Two-dimensional measurements of LV wall thickness were assessed in four segments (anterior and posterior interventricular septum, inferior, and antero-lateral walls) at the mitral valve, papillary muscles and apical levels by parasternal short-axis views. In addition, LV EF was calculated by the Simpson biplane method. (12) As measures of global LV diastolic function peak velocities at the early (peak E) and late (peak A) diastole, their ratio, deceleration time of the E wave and isovolumic relaxation time (IVRT) were assessed by pulsed-Doppler with the sample volume placed at the mitral valve leaflet tips and at the aortic outflow. (13) Finally, by pulsed tissue Doppler, peak early diastolic velocity on the septal part of the mitral annulus was measured (E′) and E/E′ ratio was calculated.