Parameters of Right Ventricular Function Reveal Ventricular-Vascular Mismatch as Determined by Right Ventricular Stroke Work versus Pulmonary Vascular Resistance in Children with Pulmonary Hypertension

Abstract

Background: Right ventricular (RV) failure, a determinant of outcomes in pulmonary hypertension (PH), occurs when the right ventricle cannot compensate for increased afterload. The authors showed that RV stroke work (RVSW) can be estimated in children with PH as the product of stroke volume and RV pressure and is related to adverse outcomes. The aim of this study was to test the hypothesis that ventricular-vascular (VV) mismatch (high afterload and low RVSW) is associated with echocardiographic measures of RV performance and adverse outcomes.

Methods: Invasive hemodynamic data and concurrent echocardiograms were reviewed. Fifty subjects with PH were included. Four groups were created by dividing the patients using median RVSW and median pulmonary vascular resistance. For each group, tricuspid annular plane systolic excursion, fractional area change, myocardial performance index, and anterior RV wall thickness were determined. Both major (i.e., death) and minor (i.e., worsening World Health Organization class) clinical outcomes were tabulated. Groups were compared using the Kruskal-Wallis or Fisher exact test.

Results: Patients in the high pulmonary vascular resistance/low RVSW cohort (VV mismatch) had the worst RV dysfunction: median tricuspid annular plane systolic excursion, 0.8 cm (interquartile range, 0.7-0.8 cm; P = .0002); median fractional area change, 0.29% (interquartile range, 0.27%-0.30%; P = .004); median myocardial performance index, 0.622 (interquartile range, 0.548-0.789; P = .0004). This group had the highest incidence of adverse outcomes: major events in 40%, minor events in 80%, and syncope in 60%.

Conclusion: VV mismatch in pediatric PH can be assessed using RVSW and pulmonary vascular resistance and is associated with RV performance and adverse events. RVSW increases in compensated high-afterload states and falls as the right ventricle fails to meet increased load; thus, VV matching status may be a sensitive predictor of outcomes in pediatric PH.

Keywords: Pulmonary hypertension; Right ventricular function; Stroke work.