Three-dimensional echocardiographic assessment
Six-beat full-volume 3D acquisitions, with electrocardiographic gating
during breath holding, were performed after the 2D examination by the
same researcher using the 4V probe. LV-focused 3D data sets were
obtained from the apical four-chamber view, while RV-focused 3D data
sets were obtained from the apical RV-focused view, as recommended
[12]. Image post-processing and reconstruction were performed
offline using 4D Auto-LVQ software (EchoPAC BT 12, GE
Vingmed-Ultrasound, Horten, Norway) for the LV volumes and LVEF and 4D
RV-Function software (TomTec Imaging Systems, Unterschleissheim,
Germany) for the RV volumes and RVEF (Figure 1). The endocardial surface
of the ventricles was traced at both end-systole and end-diastole [14,
15]. Subsequently, the software generated the biventricular volumes
and ejection fractions.
We estimated the RVPAC non-invasively as the ratio between the 3D RV SV
and the 3D RV ESV. This ratio has been previously used as a marker of
the ventriculo-vascular interaction [7, 22, 23] and it has shown
good correlation with invasive RVPAC derived from RHC [13].