ABSTRACT
Neonatal pulmonary hypertension is characterized by hypoxic respiratory failure and driven via an elevation in pulmonary artery (PA) pressure and a sustained exposure to increased afterload by the right ventricle (RV). The RV and PA circulation function as one unit, referred to as the RV-PA axis. The challenge in neonatal pulmonary hypertension is for the RV to remain hemodynamically coupled to a compliant PA circulation. The degree of RV failure is the major determinant of morbidity and mortality associated with pulmonary hypertension in the neonatal population. In this chapter, we discuss the pulmonary circulation and the right/left ventricular remodeling associated with progressing pulmonary hypertension. The concept of RV-PA coupling is introduced with a focus on the perturbations that lead to abnormal RV-PA interactions, including interactions with the left ventricle. Finally, we present up-to-date echocardiography methods used in the comprehensive assessment of RV systolic and diastolic function, RV afterload, and RV morphology. A comprehensive understanding of the determinants and tools to characterize the RV-PA axis offers a pathway to define causes and optimally manage, improve survival and reduce morbidity in neonatal pulmonary hypertension.
