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The pulmonary valve is located on the right side of the heart between the right ventricle and pulmonary artery.

In a normal functioning heart, the opening to the pulmonary valve has three flaps that open and close like one way doors. As these flaps open and close they force blood to flow forward into the pulmonary artery and backward into the right ventricle then forward again to the lungs where the blood becomes oxygenated.

With pulmonary atresia, the flap-like openings are completely covered by a layer of tissue, thus preventing the ability of blood flow to the lungs to become oxygenated.

There are two types of pulmonary atresia: The first type is called pulmonary atresia with intact ventricular septum (PA-IVS). PA-IVS is a rare congenital lesion.

Type 1 - Atresia with Intact Ventricular Septum: This lesion can be diagnosed during the fetal stage of life by using fetal echocardiography, which is a test that uses sound waves to look at the structure of an unborn baby's heart. PA-IVS involves complete blockage of the pulmonary valve located on the right side of the heart. This blockage thus prevents the flow of blood to the lungs. Because of this lack of blood flowing through the right side of the heart, the structures on that side, such as the pulmonary valve and the tricuspid valve, are abnormally small. The genetic cause of PA-IVS is unknown. It is rare, occurring in around 7.1-8.1 per every 100,000 live births.

Type 2 - Atresia with Ventricular Septal Defect: The second type of pulmonary atresia is called pulmonary atresia with ventricular septal defect or VSD. PA-VSD is identified by underdevelopment of the right ventricle. It is a second opening in the ventricular wall. This opening provides a way out for blood in the right ventricle. When this second opening (VSD) does not exist, very little blood goes to the right ventricle, which is what causes it to be underdeveloped. This defect can also be determined before birth. Out of all congenital cardiac malformations, it is estimated that PA-VSD occurs in 2.5-3.4% of the cases. The genetic cause of PA-VSD is not known; it is found however, that children whose parents have PA-VSD are at a higher risk for congenital heart lesions.

Ventricular Septal Defect and MAPCAs (major aortopulmonary collaterals): A form of Tetralogy of Fallot in which there is complete obstruction of the Pulmonary Artery resulting in total diversion of blood from the right ventricle into the aorta.

Treatment: Ultimately, a series of surgeries will be needed to improve the blood flow permanently. The first surgery will likely be performed shortly after birth. A shunt can be created between the aorta and the pulmonary artery to help increase blood flow to the lungs. As the child grows, so does the heart and the shunt may need revised in order to meet the body's requirements. Children with pulmonary atresia will need to be seen regularly throughout their lifetime by a cardiologist to be sure that their heart is functioning properly. Due to their increased risk of endocarditis, children diagnosed with pulmonary atresia should have amoxicillin before any type of dental work or other types of surgeries to help prevent this infection from occurring.

The type of surgery recommended depends on the size of the right ventricle and the pulmonary artery. If they are normal in size and the right ventricle is able to pump blood, open heart surgery can be performed to make blood flow through the heart in a normal pattern. If the right ventricle is small and unable to act as a pump, doctors may perform another type of operation called the Fontan procedure. In this two-stage procedure, the right atrium is disconnected from the pulmonary circulation. The systemic venous return goes directly to the lungs, by-passing the heart.

Some patients initially require enlargement of the atrial septal defect (ASD) via heart catheterization. The ASD is enlarged to allow more mixing of the blood. This is done surgically or through a cardiac cath procedure called a balloon septostomy. A balloon is fed through a catheter into the right atrium through the atrial septal defect and into the left atrium. It is then inflated and withdrawn to create a larger opening. Sometimes infants with pulmonary atresia and intact ventricular septum have an under-developed tricuspid valve and/or right ventricle, too. When this happens, additional surgery is needed to correct the problem.

Most of the time, infants with PA have more than one operation. The first operation is most often the placement of a small tube (shunt) from the aorta or one of its branch vessels to the pulmonary artery branch (MDfied Blalock Taussig Shunt). The shunt is put in to give more blood to the lungs so the infant will have more oxygen-rich blood to the body. The PDA is also removed. The shunt is done through a thoracotomy (side) incision. The shunt may be placed on the left, right or both sides of the pulmonary artery branch. The shunt(s) will be removed at the time of the corrective operation when no longer needed.

The corrective surgery is aimed at directing the blood from the bottom right chamber of the heart to the branch arteries going to the lungs. This can be accomplished with a patch or tube repair. For the patch repair, the narrowing beneath the pulmonary valve is cut away. An incision is made into the pulmonary artery and a large patch is sewn into it to enlarge it. The patch is a piece of the sac that the heart sits in (pericardium). The hole between the top two chambers of the heart is closed with a patch. This surgery is done through a MDan sternotomy (chest) incision.

For the tube repair, the narrowing beneath the pulmonary valve is cut away. A tube is placed in the bottom right heart chamber and sewn into the branch pulmonary arteries. This tube is often a homograft (human tissue vessel) but can also be from man-made materials. The hole between the top two chambers of the heart is closed with a patch. This surgery is done through a median sternotomy (chest) incision.

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