Absent pulmonary valve
Definition
Absent pulmonary valve is a rare defect in which the pulmonary valve that carries oxygen-poor blood from the heart to the lungs is either missing or poorly formed. This condition is present at birth (congenital).
See also: Tetralogy of Fallot
Causes
Absent pulmonary valve occurs when the pulmonary valve doesn’t develop properly while the baby is in the mother’s womb. It often occurs as part of a rare condition called tetralogy of Fallot.
The pulmonary valve is either absent or poorly formed and the ring that holds the valve in place (annulus) is usually small. This leads to a blockage in the flow of blood across the valve, and valve leakage.
There is also usually a hole between the left and right ventricles of the heart (ventricular septal defect). One of the most important parts of this syndrome is very enlarged (dilated) branch pulmonary arteries, which press on the tubes that bring air to the lungs (bronchi).
Other heart defects that can occur with absent pulmonary valve include:
- Abnormal tricuspid valve
- Atrial septal defect
- Double outlet right ventricle
- Ductus arteriosis
- Endocardial cushion defect
- Marfans syndrome
- Tricuspid atresia
Heart problems that occur with absent pulmonary valve may be due to defects of the genes (chromosomes).
Symptoms
When the pulmonary valve is missing, the branch pulmonary arteries are very enlarged and press down on the airways in the lung (bronchial tubes), causing breathing problems.
Symptoms can vary depending on which other defects the infant has, but may include:
- Blue coloring to the skin (cyanosis)
- Coughing
- Rapid breathing
- Respiratory infections
- Wheezing
Treatment
Infants who have breathing symptoms should have surgery as quickly as possible. Even infants without symptoms should have surgery within the first 3-6 months of life.
Depending on the type of heart defects the infant has, surgery may involve:
- Closing the hole in the wall between the left and right ventricles of the heart (ventricular septal defect)
- Correcting a blood vessel that connects the aorta of the heart to the pulmonary artery (ductus arteriosis)
- Enlarging the flow from the right ventricle to the lungs
Types of surgery for absent pulmonary valve include:
- Moving the pulmonary artery to the front of the aorta and away from the airways
- Rebuilding the artery wall in the lungs to reduce pressure on the airways (reduction pulmonary arterioplasty)
- Rebuilding the windpipe and breathing tubes to the lungs
- Replacing the abnormal pulmonary valve with one taken from human or animal tissue
Infants with severe breathing symptoms may need to get oxygen or be put on a breathing machine.
Prognosis
Without surgery, most infants who have severe lung complications will die.
Surgery can treat the condition and relieve symptoms in many cases.
Prevention
There is no way to prevent this condition; however, families can have genetic testing to determine their risk of certain related heart defects.