We read with interest the article “Value of Tissue Doppler Echocardiography in Children With Pulmonary Hypertension” by Lammers et al. In our opinion, this is a very interesting report describing right ventricular (RV) dysfunction in children with idiopathic pulmonary artery hypertension (PAH). The investigators clearly stated that there is a need for a detailed evaluation of RV functional parameters such as tricuspid annular plane systolic excursion (TAPSE) in their population to provide further insight into RV dysfunction in this setting and therefore help clinicians optimize treatment for RV failure. They found that TAPSE was significantly reduced in patients with PAH compared with controls. They stated that, although not significant, there was a slight difference in body weights between the control group and the PAH group and that therefore, the data may lack some statistical power. We think that these data are highly valuable and would like to mention that with a comparison of their patients with PAH against available normal pediatric TAPSE values and Z scores, this possible lack of statistical power could be overcome. We agree with the statement of Lammers et al. that pediatric data on idiopathic PAH are still lacking. In addition to their interesting data and other data from infants with PAH secondary to diaphragmatic hernia, we want to add that data on reduced TAPSE and tricuspid annular peak systolic velocity (S′) values in pediatric patients with PAH secondary to congenital heart diseases are available. In accordance with this group and other groups, we are also convinced that TAPSE and S′ closely reflect RV free wall function. In our opinion, it would be very interesting to investigate their idiopathic PAH patient group as well as our pediatric patients with PAH secondary to congenital heart diseases in longitudinal follow-up investigations to determine the time point at which TAPSE values fall below −2 standard deviations of normal values, as systolic RV function progressively deteriorates over time.

We wish to thank Lammers et al. for addressing the need for careful and systematic evaluation of RV long-axis function in patients with idiopathic PAH. Data on RV systolic function are now available for pediatric patients with idiopathic PAH, infants with PAH secondary to diaphragmatic hernia, and patients with PAH secondary to congenital heart diseases. In the future, with increasing data in pediatric patients with PAH, TAPSE and/or S′ may become the techniques of choice for the routine assessment of systolic RV function in the follow-up of patients with PAH.