Pulmonary atresia: what it is, symptoms, causes and treatment

By Cristiano Antonino On Mar 25, 2023

Normally, venous blood from the systemic circulation reaches the heart via the two hollow veins that flow into the right atrium; the tricuspid fills the right ventricle which pumps the blood into the pulmonary artery towards the pulmonary circulation where the blood is oxygenated

From the lungs, the blood will then return to the heart via the pulmonary veins in the left atrium, pass the mitral valve to fill the left ventricle so that the blood is carried to the aorta, and to the rest of the body.

Pulmonary atresia is a congenital heart defect of the pulmonary valve, which allows blood directed to the lungs to flow out of the right ventricle.

In this disease, if the pulmonary valve is completely closed, there is complete atresia; if the valve is almost closed, there is critical pulmonary valve stenosis.

In pulmonary atresia, the pulmonary valve will not form

The right ventricular outflow pathway will be obstructed by the closure of the pulmonary valve orifice by a diaphragm, preventing blood from flowing from the right ventricle to the lungs.

This will not be a problem before birth as the placenta will provide the fetus with the necessary oxygen.

Blood entering the right cavities of the heart will pass through the foramen ovale into the left atrium and into the left ventricle, so oxygen-rich blood will be carried to the rest of the body through the aorta.

After birth, the lungs must ensure oxygenation of the blood.

The foramen ovale may close after birth but usually remains open.

The ductus arteriosus of Botallo closes a few days after birth but will be kept open by medication; there may also be communication between the two ventricles.

If there is no functioning pulmonary valve, the blood will have to find a secondary route to the lungs.

The blood entering the right ventricle will pass from the foramen ovale into the left atrium and through the tricuspid valve into the right ventricle if there is no communication between the two ventricles, the blood will be regurgitated into the right atrium through the tricuspid valve.

The only way for blood to flow to the lungs will be via the pervious ductus arteriosus of Botallo, so there will be a duct-dependent pulmonary circulation.

Pulmonary atresia will be of two types: pulmonary valve atresia with an intact interventricular septum and pulmonary valve atresia with an interventricular defect.

In pulmonary atresia with an intact interventricular septum

The duct is destined to close, as the situation could degenerate abruptly, at birth it will be necessary to administer prostaglandins in order to keep the duct open, maintain pulmonary flow and allow the first palliative procedures to be organised, such as balloon valvulotomy if the flaps of the pulmonary valve are fused, one could perforate the valve by creating a small hole in the centre using a radiofrequency catheter or a wire and then open the flaps using a balloon catheter; placement of a stent in the ductus arteriosus of Botallo, placing a stent in the channel connecting the aorta and the pulmonary artery (ductus arteriosus) allowing blood to reach the lungs; systemic-pulmonary shunt, which may be necessary in the first few days of life to increase blood flow to the lungs by creating a connection between one of the arteries and the pulmonary artery using a small tube of synthetic material; balloon atrio-septomy which, in rare cases, will see the need to widen the foramen ovale to increase the amount of blood that can be sent to the lungs; the repair will be performed in the following months or years and may be a one-and-a-half ventricle repair, a biventricular correction, depending on the degree of development of the right ventricle.

In pulmonary atresia with interventricular defect

In this type of atresia, the pulmonary valve and its branches may be very small or even non-existent; if they are non-existent, the arteries from the aorta will supply blood to the lungs, these arteries will be the main aorto-pulmonary collateral arteries.

Cardiac catheterisation and/or a cardiac CT scan may be necessary to study the pulmonary arteries, in addition to palliative procedures, if the aorto-pulmonary collateral arteries are present, the pulmonary circulation will no longer be ductus arteriosus dependent.

The definitive treatment will depend on the presence and characteristics of the aorto-pulmonary collaterals, the size of the pulmonary artery and the development of the right ventricle.

In the case of well-developed pulmonary arteries without major aorto-pulmonary collateral arteries, a radical correction could be carried out in the neonatal period, with the placement of a valved conduit between the right ventricle and the pulmonary artery and closure of the interventricular defect.

In the presence of major aorto-pulmonary collateral arteries, depending on their distribution and size, the repair may take place in one or two stages by unifocating the aorto-pulmonary collaterals.

Diagnostic tool, will be echocardiography as it will provide the necessary data for diagnosis and surgical treatment.

The main symptom is cyanosis, with progressive lowering of the amount of oxygen in the blood as a consequence of the closure of the duct and the reduction of blood flow to the lungs.

In addition, an increased respiratory rate and difficulty in feeding will be present, a clear sign of the infant’s inability to perform physical exertion, to which he also responds with excessive sweating.

It will be intervened with intravenous treatment with prostaglandins as they will temporarily prevent the ductus arteriosus from closing.

The surgery will increase the blood flow to the lungs by developing the right ventricle for use during the definitive correction.

The first, palliative operation will see the opening of the pulmonary valve and the neighbouring right ventricular tract by enlarging this area with biocompatible material.

If this is not enough to ensure adequate pulmonary flow, a systemic pulmonary shunt will be added.

An evaluation of the right ventricle will then be performed, its size will have increased, it will be connected to the pulmonary artery by closing the communications created with the palliative intervention.

If the right ventricle is still small, it cannot be used in the definitive intervention, which will be monoventricular: the systemic venous system will be surgically connected directly to the pulmonary arteries, without reaching the heart, but flowing directly into the pulmonary circulation.

Only after being oxygenated will it reach the heart and then the aorta.

In the post-surgical follow-up, regular cardiological checks must be performed.

The patient, once the correction has taken place and/or the picture has stabilised, will have to undergo six-monthly and annual check-ups; he will be supported by a cardiologist; radiological/interventional tests will then be requested in order to have better monitoring.

Heart: What Are Premature Ventricular Contractions?

Heart, Bradycardia: What It Is, What It Involves And How To Treat It

What Is Bradycardia And How To Treat It

Interventricular Septal Defect: What It Is, Causes, Symptoms, Diagnosis, And Treatment

Supraventricular Tachycardia: Definition, Diagnosis, Treatment, And Prognosis

Ventricular Aneurysm: How To Recognise It?

Atrial Fibrillation: Classification, Symptoms, Causes And Treatment

EMS: Pediatric SVT (Supraventricular Tachycardia) Vs Sinus Tachycardia

Atrioventricular (AV) Block: The Different Types And Patient Management

Pathologies Of The Left Ventricle: Dilated Cardiomyopathy

A Successful CPR Saves On A Patient With Refractory Ventricular Fibrillation

Atrial Fibrillation: Symptoms To Watch Out For