The Added Value of 3D Echo to Assess RV Geometry and Function

Abstract

Quantitative assessment of the right ventricle (RV) by conventional echocardiography is a challenging task due to its complex asymmetric geometry (limiting the ability to adequately visualize both inflow and outflow tracts in the same view), highly trabeculated endocardial borders, lack of precise anatomic landmarks, and unfavourable position of the RV in the chest. Furthermore, two-dimensional echocardiography (2DE) diameters of the RV vary significantly with minor rotation or tilting the transducer and may be inaccurate, leading to an under- or overestimation of RV size. Three-dimensional echocardiography (3DE) opened a new era in echocardiographic evaluation of the RV. 3DE allows to include all three parts of the RV (i.e. inflow, outflow and apical trabecular part) in the same dataset. RV acquisitions derived from stitching together consecutive multi-beat volumes offer high temporal and spatial resolution. These data sets can be further analysed using dedicated software packages to obtain the mapping of the RV endocardial surface and to measure the RV volumes and function without using geometrical assumptions or approximations. Despite a slight underestimation, RV 3DE measurements closely correlate with RV volumes measured by cardiac magnetic resonance (CMR) and by volumetric thermodilution during cardiac catheterization both in children and adults. It’s worth stressing out that 3DE remains the only echocardiographic technique capable of a reliable calculation of RV EF from end-diastolic and end-systolic volume measurements. In the most recent meta-analysis aimed to explore the accuracy of different imaging modalities (2DE, 3DE, radionuclide ventriculography, computerized tomography- CT, gated single-photon emission CT, and invasive cardiac cineventriculography) for RV EF using CMR as reference method, 3DE has proven to be the most reliable technique, overestimating the RV EF only by 1.16% (range -0.59 to 2.92%). Normative data for 3DE RV volumes and EF including age-, body size-, and sex-specific reference values based on large cohort studies of healthy volunteers is also available. Inclusion of the recommendations for 3D RV volumetric analysis in laboratories with appropriate 3D platforms and experience in the most recent edition of chamber quantification guidelines highlights the importance of 3DE in the assessment of RV.