Regional right ventricular remodeling and function in children with idiopathic pulmonary arterial hypertension vs those with pulmonary valve stenosis: Insights into mechanics of right ventricular dysfunction.

Background: Right ventricular (RV) pressure overload in the context of pulmonary stenosis (PS) has a much better prognosis than in the context of idiopathic pulmonary arterial hypertension (iPAH), which may be related to differences in global and regional RV remodeling and systolic function. We compared RV mechanics in children with PS to those with iPAH, aiming to identify mechanisms and markers of RV dysfunction. Methods: Eighteen controls, 18 iPAH and 16 PS patients were retrospectively studied. Age, BSA, and sex distribution were comparable. Two-dimensional echocardiography, blood flow and tissue Doppler, and longitudinal RV deformation were analyzed. ANCOVA-including RV systolic pressure (RVSP) and length as covariates-was used to compare patient groups. Results: RV systolic pressure was higher in iPAH vs PS (96.8 +/- 25.4 vs 75.4 +/- 18.9 mm Hg, P=.011). Compared to controls, PS patients showed mild dilation (P <.01) and decreased longitudinal deformation (P <.001) at the RV apex. Compared to both PS and controls, iPAH patients showed marked spherical RV dilation (P <.001), reduced global, RV free wall and septal longitudinal deformation (iPAH -22.07%+/- 4.35% vs controls -28.18%+/- 1.69%; -9.98%+/- 4.30% vs -17.45%+/- 2.52%; P <.001) and RV postsystolic shortening (P <.001). RV transverse shortening (radial performance) was increased in PS (31.75%+/- 10.35%; P <.001) but reduced in iPAH (-1.62%+/- 11.11% vs controls 12.00%+/- 7.74%; P <.001). Conclusion: Children with iPAH demonstrate adverse global and regional RV remodeling and mechanics compared to those with PS. Mechanisms of RV systolic dysfunction in iPAH include decreased longitudinal deformation, decreased or absent transverse shortening, and postsystolic shortening. These markers may be useful to identify children at risk of RV failure.