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What is pulmonary valve stenosis?


Pulmonary valve stenosis describes a condition that causes narrowing of the pulmonary valve. The pulmonary valve is an outlet valve that is located in the outlet from the heart towards the lung arteries and lung circulation. A normal pulmonary valve is made of three leaflets, that open widely to allow blood to flow to the lungs when the heart pumps, and closes to prevent any blood from returning back through it when the heart relaxes. When the valve is abnormal, either the edges of the leaflets are stuck or thickened or both, or there is a smaller size and structure of the valve. The valve often has only 2 leaflets and in severe condition only one. It may be associated with narrowing above the valve (supravalvular pulmonary stenosis).



What causes pulmonary valve stenosis?

The cause is not known in most cases, but it can be associated with genetic defects such as Noonan syndrome. It can be associated with other heart conditions such as hole in the heart or more complex condition. Rare causes are infection such as Rubella during pregnancy that are transmitted to babies causing heart defects. Pulmonary valve stenosis can occur in families and there seems to be genetic basis that has not yet been identified. Screening of children born to parents with pulmonary stenosis or any congenital heart disease  is recommended.


What are the symptoms?

Babies born with very severe narrowing of pulmonary valve tend to get sick soon after birth and need urgent treatment. They may have structural problems of other valves on the right side of the heart. Most infants and children with less severe forms are diagnosed with a heart murmur picked up during assessment of non-cardiac problems. Generally, they do not have symptoms. When the valve stenosis is progressive and goes undetected, it can lead to symptoms of fatigue, breathlessness, poor exercise ability, palpitations or even fainting (syncope). Mild cases that do not progress can lead a completely normal life without needing any procedures, but regular follow-up is neccessary.


How is it diagnosed?

The diagnosis is made by clinical examination and confirmed by echocardiography. Echocardiography helps in assessing the severity of pulmonary stenosis and its effect on the heart to determine whether it needs immediate treatment. CT scan or MRI are necessary only in some patients. With the advent of fetal echocardiography, it can be diagnosed before birth particularly when moderate or severe and a care plan can be made to avoid babies from becoming too sick.


How is it treated?

When treatment is necessary, a keyhole procedure called cardiac catheterization and balloon pulmonary valvotomy (stretching the valve with a balloon catheter) is the most common way of treating the narrow valve. Although it does not change the valve, the balloon valvotomy improves its function by relieving the narrowing. It often causes the valve to be leaky to varying degrees. This is well tolerated by most patients and they can lead a normal active life. Mild to moderate pulmonary stenosis needs regular follow up and meticulous dental, skin and personal hygiene to reduce the burden of infection of the valve called endocarditis.


In some severe cases, the valve itself is underdeveloped and small, and they may need surgery to enlarge it with a patch across the valve. This invariably leads to a leaky valve and a higher chance of needing future procedures to insert a new valve by percutaneous pulmonary valve implantation or by open surgery. None of these valves last for a lifetime with a highly likely possibility of more procedures.



What is the prognosis?

Patients with a mild to moderate pulmonary valve stenosis can lead a normal active life with regular monitoring. Those with severe pulmonary stenosis need treatment but the long term outcome is very good. Despite the need for keyhole (catheterization) or open heart surgery, with regular monitoring children can have a good quality of life with normal or near normal life span.

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