At times there is abnormal development of the fetal heart in infants due to some defects coming about during the first 7 or 8 weeks of pregnancy .When  one persists this problem, blood flow from the right ventricle to the lungs get obstructed. A child may have varying degrees of pulmonary stenosis, those with the mild ones do not exhibit the symptoms at all while those with severe cases can be seriously ill.
 
Although there is no precise explanation for the abnormal development of the fetal heart, many believe that heart defects that are congenital are caused due to gene or chromosome defects and sometimes also the environmental factors can be the reason of your heart disease.

Moderate cases are not so much a matter of concern but severe ones do need special care as due to the blockage, proper flow of blood is restricted and so the right ventricle has to do extra work and eventually there is swelling which it cannot handle the extra pressure. Bacterial endocarditis is a type of infection you might earn due to pulmonary stenosis.

In order to determine whether one is suffering from pulmonary stenosis or not, you should look out for the following symptoms. Rapid breathing as well as shortness and difficulties in breathing are some common symptoms. Fatigue and abnormal heart rates are also some useful signs. Frequent urgency to urine and swelling in the ankles, face, eyelids abdomen are some symptoms which may help you to detect the disease.

As for treatment, moderate or mild cases are cured without going into lengthy treatment. But severe cases do require special attention. A doctor would go for a treatment keeping in mind the severity of the problem of the patient, his medical history, his response to different types of medicines and accordingly would treat the child. In some cases there is even need to repair the valve. Valvotomy and ballon dilation are some of the repair options available.