Approximately 1 in 50,000 babies are diagnosed with absent pulmonary valve, with most of these diagnoses occurring before birth. The more common type of APVS, Fallot type APVS occurs in 0.2–0.4% of infants born with congenital heart disease. Non-Fallot type APVS is rare with unknown frequency.

Absent pulmonary valve syndrome (APVS) is caused by an abnormal formation of the pulmonary valve in an infant during pregnancy. It often resembles a hole between the left ventricle and right ventricle in the heart, preventing adequate blood flow from one chamber to another. APVS is often associated with other heart complications, especially those combined to make up the disorder Tetralogy of Fallot (see this disease summary). While the cause of this abnormal formation is not known, there are certain chromosomal abnormalities (or abnormal mutations, additions, or deletions of genes within a person’s chromosome) that are associated with absent pulmonary valve syndrome:

1. About 25% of cases have either Trisomy 13 (Trisomy is an extra chromosome in addition to the two inherited from parents), Trisomy 21, or chromosome 6 or 7 deletions

2. Another 25% of cases have a chromosome 22q11 microdeletion

These conditions do not necessarily always contribute to APVS in infants, but they have been seen in cases of APVS and may somehow be tied to abnormal heart development.

The symptoms of absent pulmonary valve syndrome are centered around cardiac complications and the lack of oxygen available in the blood for distribution into the body. Low levels of oxygen in the blood leads the body’s skin to have a bluish color (cyanosis). Additionally, if the absence or malformation of the pulmonary valve leads to an enlarged branch of the pulmonary arteries, this compresses bronchi in the lungs and can cause difficulty breathing. Other physical symptoms that may appear in infants with absent pulmonary valve syndrome include coughing, poor appetite, rapid breathing or wheezing, and a failure to thrive. There are other heart defects that can be experienced in combination with absent pulmonary valve and may indicate the presence of a genetic mutation leading to heart complications:

• Abnormal tricuspid valve

• Atrial septal defect

• Double outlet right ventricle

• Ductus arteriosis

• Endocardial cushion defect

• Marfan syndrome

• Tricuspid atresia

• Absent left pulmonary artery

About 42.8% of infants with APVS are born with other physical characteristics including an abnormal opening in the diaphragm (diaphragmatic hernia), facial features such as cleft lip and palate, more than 5 fingers and/or toes (polydactyly), brain and spinal cord abnormalities known as neural tube defects, blockage between the stomach and small intestine (duodenal atresia), and stretched or swollen kidneys due to the build-up of urine (hydronephrosis).

Infants with absent pulmonary valve syndrome have a higher chance of survival if the diagnosis of this rare disease is made before birth. This evaluates the health of the fetus to identify and avoid potential complications. APVS can coincide with other heart complications in infants such as Tetralogy of Fallot, and tests for diagnosis should be run in the case of other identified heart problems. 

In order to monitor the health of the developing fetus, ultrasounds and echocardiograms are performed. An echocardiogram uses sound waves to construct an image of the heart of a baby in the uterus (in utero). If the pulmonary arteries have a “bow-tie” or a “balloon-like” shape, APVS is suspected. Diagnosis is more difficult during early pregnancy and infant heart development must be monitored as the pregnancy progresses. The following tests are performed once the baby is born to diagnose potential heart problems:

• Electrocardiogram - measures the electrical activity of the heart

• Heart CT scan

• Chest x-ray

• MRI of the heart

The only treatment for absent pulmonary valve syndrome is to reconstruct the heart through surgery to enable better blood flow to the lungs. The degree of malformation of the heart and the effect on an infant’s breathing determines how early heart surgery must be performed, with some newborns requiring repairs to their heart right after birth and some developing and needing it after 3-6 months of life. The surgery itself depends on how the valves of the heart have formed and some possible surgery options are described below: 

• Ventricle septal defect - closing the hole between the left and right ventricles in the heart

• Ductus arteriosus - closing the blood vessel connecting the aorta to the pulmonary artery

• Redirecting the flow of blood or enlarging the valve that allows blood to flow from the right ventricle to the lungs

• Moving the pulmonary artery to the front of the aorta and away from the lungs to prevent blocking the airway

• Pulmonary plication and reduction arterioplasty - rebuilding the artery wall of the lungs to open up airways

• Rebuilding windpipe and adding breathing tubes to the lungs

• Replacing damaged or nonexistent pulmonary valve with a newly rebuilt one from human/animal tissue

Some infants may require breathing tubes and/or a ventilator to aid their breathing if the pressure of abnormal blood flow is affecting the airways leading to their lungs. This respiratory intervention can occur before or after surgery.

Surgery is necessary for infants born with absent pulmonary valve syndrome (APVS) to enable proper function of the heart and the flow of oxygen into the blood. Without surgery, there is a very poor chance of infant survival, and cardiac and respiratory problems will occur and lead to a multitude of complications. Surgery is often successful, with an overall 10-year survival rate of 82% and a rate of no longer needing any physical intervention to maintain heart function of 81%. A successful surgery can reverse symptoms of APVS and prevent long-lasting complications, leading to a positive outlook.

1. Grewal DS, Chamoli SC, Saxena S. Absent pulmonary valve syndrome - Antenatal diagnosis. Med J Armed Forces India. 2014 Apr;70(2):198-200. doi: 10.1016/j.mjafi.2013.07.002. Epub 2013 Sep 26. PMID: 24843213; PMCID: PMC4017172. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4017172/#:~:text=Absent%20pulmonary%20valve%20syndrome%20(APVS)%20also%20known%20as%20congenital%20absence,(MPA)%20is%20always%20present. 

2. Nair AK, Haranal M, Elkhatim IM, Dillon J, Hew CC, Sivalingam S. Surgical outcomes of absent pulmonary valve syndrome: An institutional experience. Ann Pediatr Cardiol. 2020 Jul-Sep;13(3):212-219. doi: 10.4103/apc.APC_111_19. Epub 2020 Jun 23. PMID: 32863656; PMCID: PMC7437628. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7437628/#:~:text=Results%3A,monocusp%2C%20or%20transannular%20patch%20techniques. 

3. https://www.mountsinai.org/health-library/diseases-conditions/absent-pulmonary-valve

4. https://adc.bmj.com/content/106/9/877 

5. https://my.clevelandclinic.org/health/body/24273-pulmonary-valve