Two-dimensional echocardiographic assessment
All patients underwent comprehensive two-dimensional (2D) echocardiographic examinations, performed with a Vivid E9 (GE Vingmed, Horten, Norway) ultrasound machine equipped with a M5S probe, according to current recommendations [15]. Three experienced researchers performed offline data analysis using dedicated software (EchoPAC BT 12).
LV dimensions, systolic and diastolic function were assessed according to international recommendations [14-16]. LV volumes and LV ejection fraction (EF) were measured using the biplane Simpson method from the apical four- and two-chamber views. Using pulsed-wave tissue Doppler imaging (TDI) at the septal and lateral site of the mitral annulus, we calculated myocardial velocities and we estimated LV filling pressures from the ratio of early diastolic transmitral velocity (E) to average e’ wave. For LV global longitudinal strain (GLS), we used high frame rate acquisitions (50-70 frames per second) and a 17-segment model by speckle tracking echocardiography (STE), as previously described [17].
Conventional parameters of RV function such as tricuspid annular plane systolic excursion (TAPSE), peak systolic TDI velocity of the tricuspid annulus (S wave) and RV fractional area change (RV-FAC) were measured from apical RV-focused view, according to current guidelines [15, 18]. For RV strain analysis we used software designed for the LV (EchoPAC – Q Analysis package) and we manually traced the endocardial border of the RV from the apical RV-focused view, as recommended [19, 20]. The RV free wall (RVFW) and the interventricular septum were each divided into three segments. The global longitudinal strain of the RV (GLS-RV) represents the average of all six segmental strain values. The longitudinal strain of the RVFW (RVFW-LS) is the average of the segmental values of the RVFW. Estimation of pulmonary artery systolic pressure (PASP) was made using the gradient between the RV and the right atrium (RA) – obtained from the continuous-wave Doppler spectrum of the tricuspid regurgitation (TR) jet – and the estimated RA pressure, based on the inferior vena cava (IVC) diameter and respiratory changes [15]. TR severity was graded based on qualitative Doppler criteria, such as color flow jet area and the shape and density of the TR jet envelope [21].