P6467Pressure-mediated changes in the ventricular septum shape during exercise in patients with pulmonary hypertension: a 3-d echocardiography study

Abstract

Abstract Background The role of interventricular (IV) septum in mediating the mechanical interaction between the two ventricles is well recognized. This interaction is promoted by several structural and hemodynamic determinants. We aimed at assessing the geometrical RV changes in patients with pulmonary hypertension (PH) compared to normal, evaluating RV curvature at rest and during stress testing addressing the specific role of pressure-induced changes in IV septum curvature. Methods Thirty-four subjects (15 controls; 19 PH patients) underwent RV real-time 3D full volume acquisition at rest and during exercise-echo. The 3D data were analysed off-line using the 4D RV TomTec software. The 3D mesh of the RV model was post-processed using a custom developed software. The value of mean regional curvature was assessed for the interventricular septum (IVS) at end-diastole (ED) and at end systole (ES). Results In controls the IVS curvature, assessed at end-diastole (ED) and end-systole (ES), was significantly (p<0.001) more concave (at rest −0.31±0.06 at ED, and −0.29±0.06 at ES; during exercise −0.28±0.09 at ED, and −0.28±0.08 at ES) than in PH patients (at rest −0.09±0.14 at ED, and −0.09±0.11 at ES ; during exercise −0.05±0.18 at ED, and −0.02±0.18 at ES). There was no significant variation in any of RV IVS curvatures between rest and exercise or between ES and ED. In PH subjects, IVS curvature at ES weakly increased from −0.09±0.11 (SD) at rest to −0.02±0.18 during exercise (p=0.179).Nonetheless, the degree of IVS curvature was strongly related to systolic pulmonary artery pressure (PASP), both at rest (r=0.743 at ES, p<0.01; r=0.794, p<0.001 at ED) and during exercise (r=0.823 at ES, p<0.0001; r=0.812 at ED, p<0.0001). Conclusions These data provide new perspectives on how the interventricular septum morphology adapts during exercise in PH patients vs controls. Changes in IVS curvature are linearly related to pulmonary pressure changes and occur with different slope (rest-exercise) in PH vs controls.