Pulmonary Hypertension

Nicholas L. Friedman, DO, FAAP, and Samuel B. Goldfarb, MD

Introduction

•Pulmonary hypertension is an increase in the pulmonary arterial pressure that results from a decrease in functional pulmonary vasculature.

•Pulmonary arterial pressure = left atrial pressure + (pulmonary flow × pulmonary vascular resistance).

•Any single factor that increases left atrial pressure, pulmonary flow, or pulmonary vascular resistance can cause pulmonary hypertension.

•Pulmonary hypertension is defined via cardiac catheterization by a resting mean pulmonary arterial pressure of ≥25 mm Hg at sea level beyond 3 months of life.

Etiology

Five Major Categories of Pulmonary Hypertension

The World Health Organization classification of pulmonary hypertension per the Fifth World Symposium (in 2011 in Nice, France) is as follows:

1.Pulmonary arterial hypertension

a.Pulmonary veno-occlusive disease and/or pulmonary capillary hemangiomatosis

b.Persistent pulmonary hypertension of the newborn

2.Pulmonary hypertension secondary to left-sided heart disease

3.Pulmonary hypertension due to lung diseases or hypoxia

4.Chronic thromboembolic disease

5.Pulmonary hypertension with unclear or multifactorial mechanisms

Categories of Pediatric Pulmonary Hypertension

The 2013 Panama Pulmonary Hypertension Classification is as follows:

1.Prenatal or developmental pulmonary hypertensive vascular disease

2.Perinatal pulmonary vasculature maladaptation

3.Pediatric cardiovascular disease

4.Bronchopulmonary dysplasia

5.Isolated pediatric pulmonary hypertensive vascular disease (isolated pediatric pulmonary artery hypertension [PAH])

6.Multifactorial pulmonary hypertensive vascular disease in congenital malformation syndromes

7.Pediatric lung disease

9.Pediatric hypobaric hypoxic disease

10.Pediatric pulmonary vascular disease associated with other system disorders

Epidemiology

•According to the United Kingdom Service for Pulmonary Hypertension, the incidence of childhood idiopathic PAH is about 0.5 per 1 million children per year, with a prevalence of about 2 children per 1 million.

•The Tracking Outcomes and Practice in Pediatric Pulmonary Hypertension, or TOPP, registry is the largest international pediatric pulmonary hypertension database, with records for >350 children.

—In this database, there is an overall female-to-male predominance of 1.4 to 1. Eighty-eight percent of children in the database have PAH; of those, 36% have pulmonary hypertension associated with congenital heart disease (CHD). Twelve percent of children have pulmonary hypertension with a respiratory etiologic origin.