Pediatric Pulmonary Hypertension: An Integrated View From Pediatric Subspecialists

Much of current knowledge and momentum in the field of pulmonary hypertension (PH) has not penetrated the increasingly heterogeneous pediatric population managed by pediatric subspecialists worldwide. It is critical to prospectively test specific agents in children. Yet, the broad spectrum of pediatric pulmonary vascular diseases and the lack of clinically meaningful end points appropriate for the pediatric population pose challenges for the conduct of sufficiently powered pediatric studies. It is therefore no surprise that in the midst of significant advances in the field, there are no agents approved for use in children afflicted with PH with the exception of inhaled nitric oxide (iNO) for infants with persistent PH of the newborn (PPHN). The current and widely accepted WHO framework by which pediatric subspecialists are guided is not easily translated into the expanding range of situations encountered in pediatric practice. Like PPHN, it may be necessary to approach these pediatric pulmonary hypertensive conditions from outside the frameworks proposed for typical adult-onset diseases. Exploration of the potential intrinsic differences between children and adults may yield important discoveries regarding the genesis of disease in children and adults alike Fortunately, most children with PH are seen within specialized pediatric centers where there are untapped opportunities for multicenter collaboration. Our aim in this chapter is to approach pediatric PH over the age and development continuum from the vantage point of the pediatric subspecialists who encounter these patients in practice. We will review the abnormalities of pulmonary vascular tone and structure that impact the health and survival of children currently cared for in pediatric PH centers. Many of these disease processes occur commonly from our vantage point, yet are underrepresented in the broader field of PH research or current classification schemes. We will also address the challenges that pediatric subspecialists face in defining PH and assessing its severity in infants or children across the developmental and disease spectrums.