Right Ventricular Tissue Doppler Myocardial Performance Index in Children with Pulmonary Hypertension: Relation to Invasive Hemodynamics

Right ventricular (RV) failure is a significant cause of morbidity and mortality in patients with pulmonary hypertension (PH). Myocardial performance index measured by tissue Doppler imaging (TDI-MPI) has been useful in assessing RV dysfunction in adults with PH. However, TDI-MPI as a marker for RV dysfunction or disease severity has not been evaluated in pediatric PH. The aim of this study was to investigate TDI-MPI and correlate with invasive hemodynamics in pediatric PH patients. Eighty pediatric PH patients undergoing cardiac catheterization and simultaneous transthoracic echocardiography were analyzed. RV TDI-MPI was averaged over three cardiac cycles and measured under each condition of vasodilatory testing during the catheterization. TDI-MPI was compared between PH patients and age-matched controls and correlated to invasive hemodynamics. RV TDI-MPI was increased in PH patients compared to controls (0.49 vs. 0.35, p < 0.0001). Significant associations (beta +/- SE) are seen between RV TDI-MPI and baseline mean pulmonary arterial pressures (0.0002 +/- 0.001, p < 0.05), indexed pulmonary vascular resistance (0.007 +/- 0.002, p < 0.002), and pulmonary-to-systemic arterial pressure ratio (0.146 +/- 0.063, p < 0.05). No statistically significant associations were seen with vasodilatory testing. RV TDI-MPI is elevated in children with PH, suggestive of RV dysfunction. RV TDI-MPI shows correlation with severity of PH at baseline but lacks sensitivity to evaluate the RV response to acute changes in afterload in children with PH. Therefore, while RV TDI-MPI can help identify RV dysfunction in children with PH, its utility as a non-invasive surrogate marker for acute changes in hemodynamics is limited.