DESCRIPTION

Pulmonary hypertension (PH) refers to an abnormal elevation in pulmonary artery pressure.

EPIDEMIOLOGY

• The estimated incidence of sustained pulmonary arterial hypertension (PAH) in all World Health Organization (WHO) groups is 4.8 to 8.1 cases per million children per year in the United States.
• The prevalence of PAH is 25.7 to 32.6 per million children.

ETIOLOGY

• Group 1 PH
  • Includes idiopathic PAH (IPAH), heritable PAH, drug- and toxin-induced PAH, persistent PH of the newborn, PAH associated with connective tissue disease, HIV infection, portal hypertension, congenital heart disease, schistosomiasis
• Group 2 PH
  • PH due to left heart disease, valvular heart disease, diastolic and systolic dysfunction
• Group 3 PH
  • PH due to lung diseases and/or hypoxia, including developmental lung disorders, lung hypoplasia, bronchopulmonary dysplasia, congenital diaphragmatic hernia, interstitial lung disease, restrictive and obstructive lung disease, and hypoventilation
• Group 4 PH
  • Chronic thromboembolic PH
• Group 5 PH
  • PH with unclear or multifactorial factors including metabolic disorders, complex congenital heart disease, and hematologic disorders

PATHOPHYSIOLOGY

• Often multifactorial, PAH is seen as the final common outcome for multiple conditions.
• There is an imbalance of vasogenic mediators, endothelial cell dysfunction, smooth muscle cell proliferation, inflammation, mitochondrial dysfunction, and altered mechanisms of apoptosis and thrombosis.
• There is excessive vascular cell proliferation and abnormal vascular remodeling.