Pulmonary atresia
Encyclopedia
Pulmonary atresia is a congenital malformation of the pulmonary valve
in which the valve orifice fails to develop. The valve is completely closed thereby obstructing the outflow of blood from the heart
to the lungs. 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 the disease 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. The body requires oxygenated blood for survival. Pulmonary atresia is not threatening to a developing fetus however, because the mother's placenta provides the needed oxygen since the baby's lungs are not yet functional. Once the baby is born its lungs must now provide the oxygen needed for survival, but with Pulmonary atresia there is no opening on the pulmonary valve
for blood to get to the lungs and become oxygenated and the only source of pulmonary blood flow is a patent ductus arteriosus
. Due to this, the newborn baby is blue in color and pulmonary atresia can usually be diagnosed within hours or minutes after birth.
. 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.
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.
and possibly placed on oxygen and a ventilator that will help the child breathe. Also, IV medications that assist the heart and lung function may be given. An IV medication called prostaglandin E1 is used for treatment of pulmonary atresia, as it stops the ductus arteriosus
from closing, allowing mixing of the pulmonary and systemic circulations. But prostaglandin E1 can be dangerous as it can cause apnea
. Another example of preliminary treatment is heart catheterization to evaluate the defect or defects of the heart; this procedure is much more invasive. Ultimately, however, the patient will need to have a series of surgeries 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.
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.
is exceptionally small, many surgeries will be needed in order to help stimulate normal circulation of blood to the heart.
If uncorrected, babies with this type of congenital heart disease may only survive for the first few days of life while the fetal shunts between left and right circulations remain patent. However, there are cases of uncorrected Pulmonary Atresia in which the baby has survived.
Many children with pulmonary atresia will go on to lead 'normal' lives. Patients are usually seen regularly throughout their lifetime by a cardiologist to be sure that their heart is functioning properly. They have an increased risk of endocarditis
.
Pulmonary valve
The pulmonary valve is the semilunar valve of the heart that lies between the right ventricle and the pulmonary artery and has three cusps. Similar to the aortic valve, the pulmonary valve opens in ventricular systole, when the pressure in the right ventricle rises above the pressure in the...
in which the valve orifice fails to develop. The valve is completely closed thereby obstructing the outflow of blood from the heart
Heart
The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
to the lungs. The pulmonary valve is located on the right side of the heart between the right ventricle
Right ventricle
The right ventricle is one of four chambers in the human heart. It receives deoxygenated blood from the right atrium via the tricuspid valve, and pumps it into the pulmonary artery via the pulmonary valve and pulmonary trunk....
and pulmonary artery
Pulmonary artery
The pulmonary arteries carry deoxygenated blood from the heart to the lungs. They are the only arteries that carry deoxygenated blood....
. 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
Pulmonary artery
The pulmonary arteries carry deoxygenated blood from the heart to the lungs. They are the only arteries that carry deoxygenated blood....
and backward into the right ventricle
Right ventricle
The right ventricle is one of four chambers in the human heart. It receives deoxygenated blood from the right atrium via the tricuspid valve, and pumps it into the pulmonary artery via the pulmonary valve and pulmonary trunk....
then forward again to the lungs where the blood becomes oxygenated. With the disease 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. The body requires oxygenated blood for survival. Pulmonary atresia is not threatening to a developing fetus however, because the mother's placenta provides the needed oxygen since the baby's lungs are not yet functional. Once the baby is born its lungs must now provide the oxygen needed for survival, but with Pulmonary atresia there is no opening on the pulmonary valve
Pulmonary valve
The pulmonary valve is the semilunar valve of the heart that lies between the right ventricle and the pulmonary artery and has three cusps. Similar to the aortic valve, the pulmonary valve opens in ventricular systole, when the pressure in the right ventricle rises above the pressure in the...
for blood to get to the lungs and become oxygenated and the only source of pulmonary blood flow is a patent ductus arteriosus
Patent ductus arteriosus
Patent ductus arteriosus is a congenital disorder in the heart wherein a neonate's ductus arteriosus fails to close after birth. Early symptoms are uncommon, but in the first year of life include increased work of breathing and poor weight gain...
. Due to this, the newborn baby is blue in color and pulmonary atresia can usually be diagnosed within hours or minutes after birth.
Classification
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 lesionLesion
A lesion is any abnormality in the tissue of an organism , usually caused by disease or trauma. Lesion is derived from the Latin word laesio which means injury.- Types :...
. 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
Pulmonary valve
The pulmonary valve is the semilunar valve of the heart that lies between the right ventricle and the pulmonary artery and has three cusps. Similar to the aortic valve, the pulmonary valve opens in ventricular systole, when the pressure in the right ventricle rises above the pressure in the...
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
Pulmonary valve
The pulmonary valve is the semilunar valve of the heart that lies between the right ventricle and the pulmonary artery and has three cusps. Similar to the aortic valve, the pulmonary valve opens in ventricular systole, when the pressure in the right ventricle rises above the pressure in the...
and the tricuspid valve
Tricuspid valve
The tricuspid valve, or right atrioventricular valve, is on the right dorsal side of the mammalian heart, between the right atrium and the right ventricle. The normal tricuspid valve usually has three leaflets and three papillary muscles. They are connected to the papillary muscles by the chordae...
, 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.
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
Right ventricle
The right ventricle is one of four chambers in the human heart. It receives deoxygenated blood from the right atrium via the tricuspid valve, and pumps it into the pulmonary artery via the pulmonary valve and pulmonary trunk....
. 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.
Cause
Doctors are unsure of the cause of congenital heart defects, but there are some medical conditions that have been found to increase the risk of having a baby with a heart defect such as congenital heart disease in the mother, father, brother, or sister of the baby, a diabetic mother, use of drugs or alcohol or over the counter prescriptions during pregnancy. These conditions do not mean that the baby will definitely be born with a heart defect, but that it runs a higher chance. Sometimes babies are born without any of these conditions; the cause is unknown.Treatment
At first, the child will need to be admitted to the intensive care unitIntensive Care Unit
thumb|220px|ICU roomAn intensive-care unit , critical-care unit , intensive-therapy unit/intensive-treatment unit is a specialized department in a hospital that provides intensive-care medicine...
and possibly placed on oxygen and a ventilator that will help the child breathe. Also, IV medications that assist the heart and lung function may be given. An IV medication called prostaglandin E1 is used for treatment of pulmonary atresia, as it stops the ductus arteriosus
Ductus arteriosus
In the developing fetus, the ductus arteriosus , also called the ductus Botalli, is a shunt connecting the pulmonary artery to the aortic arch. It allows most of the blood from the right ventricle to bypass the fetus's fluid-filled lungs. Upon closure at birth, it becomes the ligamentum arteriosum...
from closing, allowing mixing of the pulmonary and systemic circulations. But prostaglandin E1 can be dangerous as it can cause apnea
Apnea
Apnea, apnoea, or apnœa is a term for suspension of external breathing. During apnea there is no movement of the muscles of respiration and the volume of the lungs initially remains unchanged...
. Another example of preliminary treatment is heart catheterization to evaluate the defect or defects of the heart; this procedure is much more invasive. Ultimately, however, the patient will need to have a series of surgeries to improve the blood flow permanently. The first surgery will likely be performed shortly after birth. A shunt
Shunt
Shunt may refer to:* Shunt - a hole or passage allowing fluid to move from one part of the body to another* Shunt - a device allowing electrical current to pass around a point in a circuit...
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.
The type of surgery recommended depends on the size of the right ventricle
Right ventricle
The right ventricle is one of four chambers in the human heart. It receives deoxygenated blood from the right atrium via the tricuspid valve, and pumps it into the pulmonary artery via the pulmonary valve and pulmonary trunk....
and the pulmonary artery
Pulmonary artery
The pulmonary arteries carry deoxygenated blood from the heart to the lungs. They are the only arteries that carry deoxygenated blood....
.
If they are normal in size and the right ventricle is able to pump blood, open heart surgery
Open Heart Surgery
Open Heart Surgery was released on August 8, 2000 by rock band Virginwool. The band signed to Breaking/Atlantic Records after initially beginning signed to Universal Records. The album was produced and mixed by Brad Wood....
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
Fontan procedure
The Fontan procedure, or Fontan/Kreutzer procedure, is a palliative surgical procedure used in children with complex congenital heart defects. It involves diverting the venous blood from the right atrium to the pulmonary arteries without passing through the morphologic pulmonary ventricle...
. In this two-stage procedure, the right atrium
Right atrium
The right atrium is one of four chambers in the hearts of mammals and archosaurs...
is disconnected from the pulmonary circulation. The systemic venous return goes directly to the lungs, by-passing the heart.
Prognosis
The outcome varies for every child. If the condition is left uncorrected it may be fatal, but the prognosis has greatly improved over the years for babies with pulmonary atresia. Some factors that affect how well the child does include how well the heart is beating, the condition of the blood vessels that supply the heart, and how leaky the other heart valves are. Most cases of pulmonary atresia can be helped with surgery. If the patient's right ventricleRight ventricle
The right ventricle is one of four chambers in the human heart. It receives deoxygenated blood from the right atrium via the tricuspid valve, and pumps it into the pulmonary artery via the pulmonary valve and pulmonary trunk....
is exceptionally small, many surgeries will be needed in order to help stimulate normal circulation of blood to the heart.
If uncorrected, babies with this type of congenital heart disease may only survive for the first few days of life while the fetal shunts between left and right circulations remain patent. However, there are cases of uncorrected Pulmonary Atresia in which the baby has survived.
Many children with pulmonary atresia will go on to lead 'normal' lives. Patients are usually seen regularly throughout their lifetime by a cardiologist to be sure that their heart is functioning properly. They have an increased risk of endocarditis
Endocarditis
Endocarditis is an inflammation of the inner layer of the heart, the endocardium. It usually involves the heart valves . Other structures that may be involved include the interventricular septum, the chordae tendineae, the mural endocardium, or even on intracardiac devices...
.
External links
- Pulmonary Atresia information from Seattle Children's Hospital Heart Center
- Information from Children's Hospital Boston
- Information from American Heart Association
- http://www.ctsnet.org/file/paivs_LETTER_06-25-03.pdf from Congenital Heart Surgenos' Society
- Information from Medline Plus
- Information from Texas Heart Institute