Right ventricular free wall contractility in subcostal views: A proof-of-concept study to assess right ventricular systolic function.

Abstract

Normal right ventricular (RV) function has been traditionally assessed from the apical window. However, in several patients the subcostal window is the only available acoustic. Given the intricate functional and mechanical inter-dependence between longitudinal tricuspid annular (TA) displacement and RV free wall contractility (RVFW), we studied the utility of RVFW inward motion using both M-mode and velocity with tissue Doppler imaging (TDI) from the subcostal transthoracic view. If a TAPSE value ≥ 2cm is used to identify normal RV function, an RVFW M-mode value>.8cm, TA TDI s' velocity>.06cm/s and TA TDI e' velocity value>.05cm/s identify normal RV systolic function. Furthermore, ROC curve analysis for the RVFW M-mode showed an area under the curve (AUC) of .753 (95% CI: .604-.868) with a cut-off value>.8, sensitivity 75% and specificity 73%; for TA TDI s' AUC at .822 (95% CI: .681-.919) with a cut-off value>.06, sensitivity 75% and specificity 77% and for TA TDI e' the AUC was .771 (95% CI: .624-.882) with a cut-off value>.05, sensitivity 90% and specificity 46%. Reproducibility of repeat RVFW M-mode, TDI s' and e' measurements was good with strong inter-rater agreement (Kappa>.8). The subcostal window appears useful for assessing RV systolic function. Additional studies are now required to prospectively use these measures in the routine evaluation of RV systolic function particularly in patients with suboptimal apical windows.