Abstract
Background
Right ventricle to pulmonary circulation (RV-PC) coupling plays a pivotal role during the physical effort. The RV-PC uncoupling can be easily identified by the TAPSE/SPAP ratio, a prognostic marker based on RV longitudinal function and its afterload (SPAP).We sought to explore the relationship between the functional capacity (peak VO2 and VE/VCO2) and the RV-PC coupling, using both a standard and 3D-based echocardiographic assessment of RV.
Methods
eighty-seven patients (age 72 ± 10 years; LV EF 53 ± 15%) underwent rest echocardiography with 3D RV assessment and cardiopulmonary exercise test. RV EF was measured using the 4D RV TomTec software. The 3D mesh of the RV model was post-processed using a custom developed software. This provided longitudinal (EFlong) and circumferential (EFcirc) components of EF. RV-PC coupling was assessed with the TAPSE/SPAP ratio and with similar parameters obtained by using 3D components of RV systolic function over SPAP (EF/SPAP, EFlong/SPAP and EFcirc/SPAP ratio). All variables were correlated with peakVO2 and VE/VCO2.
Results
Correlations between peakVO2 and TAPSE (0.409, p = 0.006), SPAP (-0.597, p < 0.001), RV EF (0.555, p < 0.001), RV EFlong (0.327, p = 0.03), RV EFcirc (0.587, p < 0.001) were modest, while TAPSE/SPAP (0.641, p < 0.001), EF/SPAP (0.751, p < 0.001), EFlong/SPAP (0.610, p < 0.001) and EFcirc/SPAP (0.775, p < 0.001) showed stronger correlations. VE/VCO2 showed a similar relationships although the correlations were weaker [TAPSE (-0.523, p <0.001), SPAP (0.617, p < 0.001), RV EF (-0.412, p = 0.006), RV EFlong (-0.232, p = 0.129), RV EFcirc (-0.454, p = 0.002), TAPSE/SPAP (-0.561, p < 0.001), EF/SPAP (-0.516, p = 0.001), EFlong/SPAP (-0.429, p = 0.008) and EFcirc/SPAP (-0.541, p < 0.001)].
Conclusions
RV-PC coupling is associated with both peak VO2 and VE/VCO2. The use of 3D-derived markers of RV-PC coupling showed a better correlation with the peak VO2, while there were no differences for VE/VCO2. The circumferential component of RV systolic function seems to emerge as a dominant determinant of RV-PC coupling, as well as of functional capacity.