Pediatric Idiopathic Pulmonary Artery Hypertension - An Overview

Introduction

Pulmonary hypertension is associated with various cardiac, pulmonary, and systemic diseases in neonates and children. Idiopathic pulmonary artery hypertension is a subtype of pulmonary artery hypertension and is a rare condition in children. The exact cause and risk factors of this condition are unknown. However, it can be triggered by congenital heart disease. The changes in lung histopathology in pulmonary hypertension are almost similar to those of adults or older patients. It is classified under group 1 pulmonary hypertension and can manifest in newborns and infants in the form of persistent pulmonary hypertension. There is no complete cure for this condition, and very little is known about the outcomes of the disease in children.

What Is Pediatric Idiopathic Pulmonary Artery Hypertension?

High blood pressure in the pulmonary arteries (arteries of the lungs) is known as pulmonary artery hypertension (PAH) or idiopathic pulmonary artery hypertension (IPAH). It is a progressive disease in which the pulmonary arteries shrink and make the right side of the heart work more as high pressure is required to force the blood through the narrow arteries. In some complex cases of pediatric pulmonary hypertension, there can be severe damage to the small blood vessels in the lungs due to vasoconstriction (narrowing of blood vessels due to contraction of the muscular wall), which may even damage the lungs. If left untreated, This can lead to a reduction of air spaces and blood vessels in the lungs, resulting in the enlargement of the right side of the child’s heart and may cause right ventricular failure (right heart failure).

What Are the Causes of Pediatric Idiopathic Pulmonary Artery Hypertension?

Idiopathic pulmonary artery hypertension was previously known as primary pulmonary hypertension (PPH) or precapillary pulmonary hypertension. Idiopathic means no apparent cause, and as this condition's symptoms and risk factors are not specific and the disorder is rare, the exact etiology is not clearly understood. PAH in children can also develop due to congenital heart defects (present at birth). However, most of the cases are known to be inherited or run in families because of mutation (gene defects) that makes the blood vessels more prone to vasoconstriction; hence, the disease can be fatal with a high mortality rate. Other conditions that cause pulmonary hypertension in children include congenital diaphragmatic hernia (a hole in the diaphragm), cardiomyopathy (weak heart muscles), cystic fibrosis (accumulation of thick and sticky mucus), Down syndrome (a genetic disorder), viral illnesses, and chronic blood clots.

What Are the Symptoms of Pediatric Idiopathic Pulmonary Artery Hypertension?

Some of the symptoms of pediatric idiopathic pulmonary artery hypertension include:

• Chest pain.

• Difficulty breathing or shortness of breath.

• Growth impairment.

• Poor appetite.

• Nausea and vomiting.

• Sweating.

• Tachycardia (increased heart rate).

• Tachypnea (abnormal or rapid breathing).

• Fainting.

• Bluish discoloration of the lips.

• Swelling of the lower legs or ankles.

• Dizziness.

• Fatigue.

What Are the Complications of Pediatric Idiopathic Pulmonary Artery Hypertension?

If left untreated, pediatric idiopathic pulmonary artery hypertension can lead to the following conditions:

• Alveolar Capillary Dysplasia (ACD) - Misalignment of pulmonary blood vessels that results in high blood pressure in the lungs.

• Bronchopulmonary Dysplasia (BPD) - A breathing disorder in which the lung tissues become irritated and cause cough, asthma, or wheezing throughout childhood.

• Lung Hypoplasia - Incomplete development of the lungs.

• Surfactant Protein Abnormalities - Defects in the fats and proteins that line the lungs result in breathing problems.

How Is Pediatric Idiopathic Pulmonary Artery Hypertension Diagnosed?

A complete evaluation of all the possible causes of pulmonary hypertension in children is performed before the diagnosis of IPAH is determined.

• Cardiac catheterization may be necessary to rule out congenital heart disease. It is done by inserting a thin, flexible tube called a catheter by a small incision into the groin that threads it up to the pulmonary artery.

• A lung biopsy may also be conducted to rule out other respiratory disorders.

• An echocardiogram (ECHO) is a non-invasive screening tool useful to evaluate suspected pediatric patients with pulmonary hypertension. It determines the cardiac anatomy, size, and function of the right ventricle, morphology, and function of the valves.

• Doppler ultrasound is a non-invasive imaging technique that may also be used to estimate the pulmonary artery systolic pressure or to diagnose increased pulmonary vascular resistance.

• Pulmonary vasodilator testing is performed, during which supplemental oxygen and other medications are given to relax the lungs' blood vessels. These tests mainly help the doctors gauge the response of the blood pressure in the lungs to this treatment.

How Is Pediatric Idiopathic Pulmonary Artery Hypertension Managed?

Early diagnosis is considered a vital factor in the management of idiopathic pulmonary artery hypertension. There is no permanent cure for this condition. However, there are various ways to manage the symptoms. Some of the common treatment options include:

• Oral Medications: Drugs such as Sildenafil (pulmonary vasodilator) and Bosentan (endothelin-receptor antagonist) can help lower pulmonary arterial blood pressure and improve blood flow.

• Nitric Oxide: Nitric oxide is a vasodilator that helps relax the blood vessels. It is mainly recommended for inhalation in babies with pulmonary hypertension. It is administered in the neonatal intensive care unit (NICU) and is unavailable for home use.

• Oxygen Therapy: Supplemental oxygen can be administered to children at home or in the hospital as an ongoing treatment. It helps to oxygenate the blood, reduces the pressure off the lungs, and relaxes the blood vessels.

Conclusion

Pulmonary hypertension in children usually manifests in the form of idiopathic pulmonary artery hypertension, persistent pulmonary hypertension in newborns (PPHN), or congenital heart disease-related pulmonary hypertension. It occurs when the blood puts excess force on the blood vessels' walls, making it difficult for the right side of the heart to pump blood to the lungs, where it gets oxygenated. Though rare in children, the therapeutic approach is the same as in adults. Recent advances in neonatology and echocardiography have made the diagnosis and management of the condition better, and many premature infants outgrow PAH once they begin to develop and feed. However, there may be a risk when these children grow into adults as their lung tissues are not completely normal even after significant healing. Collaboration between different healthcare specialists and the cooperation of the children and caregivers is highly necessary in managing pediatric idiopathic pulmonary artery hypertension.