The following information about pediatric pulmonary hypertension is provided for patients and families by PPHNet caregivers.

How does the heart work? The normal heart has 4 chambers, two atria and two ventricles. The right atrium receives blood with low oxygen and high carbon dioxide from the superior and inferior vena cavae, and the left atrium receives oxygen rich blood from the pulmonary veins draining the lungs. The right ventricle pumps blood to the lungs to receive oxygen via the pulmonary arteries. The lungs are made of many air-filled sacs called alveoli where carbon dioxide is exchanged for oxygen. The oxygen rich blood is collected by pulmonary veins and delivered to the left atrium and then the left ventricle where it is pumped to the rest of the body.

What is Pulmonary Artery Hypertension (PAH)? Pulmonary artery hypertension refers to elevated pressure in the pulmonary arteries.

How do we measure these pressures? Pressures in the lungs are measured non-invasively through echocardiogram or directly during a procedure called cardiac catheterization.

What happens in PAH? In pulmonary artery hypertension, the pulmonary arterioles are narrowed. This may be due to way that they are formed, because of thickening of the blood vessel walls over time or acutely in response to a stimulus. Pulmonary hypertension causes increased pressure in the right ventricle, which becomes larger and more muscular. The condition may eventually lead to right heart failure.

What are the symptoms? Older children with PAH may have shortness of breath with exercise, excessive fatigue with exercise, or fainting episodes. Infants may present with irritability, rapid breathing, poor growth or blue appearance.

What are the causes of PH?

Childhood PAH: Pediatric PH has a variety of underlying causes. Many are described below.

• Patients may have idiopathic pulmonary hypertension, without known cause or inherited pulmonary hypertension. Alternatively they may develop pulmonary hypertension as a consequence of congenital heart disease or left sided heart diseases such as pulmonary vein obstruction, mitral valve disorders and restrictive cardiomyopathy.
• Connective tissue disease and rheumatologic disorders such as scleroderma, mixed connective tissue disease, juvenile inflammatory arthritis (JIA) and lupus may be associated with PH and require multidisciplinary care coordination over time.
• Hematologic disorders including sickle cell disease and myeloproliferative disorders as well as metabolic diseases such as glycogen storage disease and mitochondrial disorders may also be associated with PAH in childhood.
• Chronic lung diseases including interstitial lung diseases and obstructive sleep apnea may be associated with pulmonary hypertension.
• Portopulmonary hypertension is PH associated with liver disease and portal hypertension.
• Pulmonary thromboembolism in which blood clots occlude the pulmonary arteries may be a rare cause of childhood PH.

PH in Infancy: Particular types of pulmonary hypertension are found in infants. These include the following:

• Pulmonary hypertension may be found in ex-premature infants with bronchopulmonary dysplasia, a chronic lung disease due to the impact of multiple factors such as low oxygen concentration on developing lungs.
• Congenital diaphragmatic hernia, a congenital defect in the diaphragm allowing abdominal contents to herniate into the chest, is another important cause of lung development associated pulmonary hypertension in babies.
• Genetic and developmental disorders with abnormal lungs (alveolar capillary dysplasia, pulmonary veno-occlusive disease, surfactant deficiencies, omphalocele, cystic adenoid malformation of the lungs and chromosomal defects like Down syndrome, may be associated with pulmonary hypertension.

What is PPHN? PPNH is persistent pulmonary hypertension of the newborn. Before birth, pressures in the right side of the heart are similar to those on the left because of the way blood circulates in the fetus. Usually, the right- sided pressures decrease in the hours and days following birth and reach normal values in the first month of life. For infants with PPHN, the pressures in the pulmonary arteries do not decrease as expected. This may be associated with perinatal stress, aspiration of meconium or infection. Infants with PPHN require coordinated NICU care to improve oxygen until the lungs recover.

In summary, pediatric pulmonary arterial hypertension is a serious and potentially life-threatening illness with multiple management challenges. A complete diagnostic work up to identify underlying causes is essential. It is important that children suspected to have PAH are referred to centers and physicians with expertise in the diagnosis and management of this condition.

Additional Resources:

Pulmonary Hypertension Association of Canada, http://www.phacanada.ca/

This content was last reviewed and updated on July 11, 2023.