Multiplane Echocardiographic Assessment of RV Wall Function

The evaluation of regional RV wall function by 2D multi-plane echocardiography has been well documented in our previous publications (12 (link), 16 (link)). In short, from a fixed apical probe position, electronic plane rotation around the RV apex allows visualisation of different RV free wall regions. Each RV wall is confirmed by the presence of a certain left-sided landmark associated with an approximate degree of electronic rotation. Throughout imaging, the RV should be non-foreshortened with the RV apex and interventricular septum centred along or as near to the midline of the imaging sector as possible. For this study, three views were utilised visualising the lateral, anterior and inferior RV wall regions. The first view at 0˚ shows the lateral RV wall with the left sided landmark being the mitral valve. The second view at approximately +40˚ shows the anterior RV wall and the coronary sinus and thirdly at approximately −40˚ the inferior RV wall and the aortic valve (Figure 1, Supplementary Videos S1–S3). The RV datasets were digitally exported to a vendor-neutral server (TomTec Imaging Systems, Unterschleissheim, Germany) and data analysis was performed offline by one experienced observer (DB). To assess peak systolic RV longitudinal strain, an RV algorithm wall motion tracking software was used (2D CPA, Image-Arena version 4.6; TomTec Imaging Systems). RV systole was determined as the time interval from electrocardiographic QRS onset to minimum RV cavity size, which was used as a surrogate for pulmonary valve closure. The endocardial borders of the RV free wall and septum were manually traced at end systole and adjusted accordingly in end diastole if required. This was performed in each of the other multi-plane views previously described. A single segment RV longitudinal strain (RV-LS) value for each wall was derived from the average of the basal, mid and apical segments. A measurement was considered feasible if all portions of the RV wall tracked acceptably throughout the cardiac cycle. If tracking was deemed inaccurate, the wall was excluded from analysis. The 3D datasets were digitally exported to the same TomTec server and analysed by DB using specialised RV analysis software (TomTec 4D-RV function 2.0). After placing set landmarks, RV volumes and ejection fraction (RVEF) were automatically calculated, with manual adjustment performed where necessary. In cases of inadequate tracking, the dataset was deemed unfeasible to measure and excluded from analysis.