Assessment of right ventricular segmental volumes and ejection fractions using a 15-segment model: three-dimensional echocardiographic study in healthy volunteers
Authors: Fabian A , Lakatos BK , Tokodi M , Ujvari A , Kispal E , Liptai CS , Csakvari M , Staub L , Toser Z , Merkely B , Kovacs A 
Published: February 2021

Abstract

Funding Acknowledgements
Type of funding sources: None.
On top of global ventricular function, segmental metrics may bear clinically relevant information. Concerning the left ventricle (LV), standardized segmentation is widely performed in different cardiovascular imaging modalities mainly to correlate regional dysfunction with coronary perfusion territories, or to appreciate and quantify distinct patterns in LV myocardial function. The same applies to the right ventricle (RV); as pulmonary hypertension, or arrhythmogenic cardiomyopathy are just two clinical examples among several others, where established regional dysfunction exists. Nevertheless, only a few options are available for the comprehensive and quantitative assessment of the segmental RV function due to its complex three-dimensional (3D) shape.
Therefore, our aim was to develop a 3D echocardiographic software solution for volumetric partitioning of the RV using a 15-segment model and to investigate a large number of healthy volunteers to describe the normal segmental pattern.
One hundred and fifty healthy adults with a balanced age range and an equal sex distribution were investigated (15-15 women and men in each age groups: 20-29, 30-39, 40-49, 50-59, 60+). Beyond standard two-dimensional echocardiographic protocol, full volume 3D datasets were acquired. Using commercially available software, we reconstructed the 3D mesh model of the RV and measured end-diastolic (EDV), end-systolic volumes and ejection fraction (EF). The 3D model was post-processed using the ReVISION method to calculate regional and segmental volumes and EFs. Fifteen standard segments were separated and quantified (Figure).
Increasing age resulted in significantly lower RV stroke volume (r=-0.17; p &lt; 0.05) and tended towards lower RV EDV (r=-0.15, p = 0.06). EDVs of inflow tract and outflow tract segments decreased during aging (r=-0.21, p &lt; 0.05 and r=-0.26, p &lt; 0.01, respectively). Between the pre-specified age groups, there was no difference concerning global RVEF (ANOVA p = NS). In the 50-59 age group, regional EF of septal segments and also free wall segments were significantly lower compared to subjects in the 30-39 and 40-49 age categories (both p &lt; 0.05). Global RV EDV was significantly lower in women (women vs. men: 95 ± 20 vs. 125 ± 28 ml; p &lt; 0.05) along with a higher RV EF compared to men (62 ± 4 vs. 59 ± 4; p &lt; 0.05). However, segmental EFs of apical, septal mid anterior, free wall mid posterior, free wall mid lateral, septal basal anterior and inflow tract segments were comparable between genders.
The ReVISION method allows a volumetric partitioning of the RV 3D models to investigate segmental geometry and function in a 15-segment model. We have explored segmental differences between different ages and genders. Further studies are warranted to justify the importance of segmental assessment of the RV in different cardiac diseases.
Abstract Figure. Separation of 15 standard RV segments