What is the most common cause of aortic stenosis in pediatric cases?

The most common cause of aortic stenosis in pediatric cases is associated with the failure of the bulbus to atrophy around the root of the aorta. This condition, often referred to as valvular aortic stenosis, typically arises due to abnormal development during fetal life, particularly affecting the aortic valve and surrounding structures. In normal embryologic development, the bulbus cordis transforms and contributes to the formation of the aorta and the aortic valve. If this process is disrupted, it can result in aortic stenosis, characterized by a narrowed valve that restricts blood flow from the heart into the aorta.

In pediatric patients, this congenital form of aortic stenosis is more prevalent than acquired causes. Other factors such as maternal drug exposure or viral infections during pregnancy may affect fetal development, but they are not as directly associated with the anatomical changes leading to aortic stenosis compared to the specific failure of the bulbus to undergo proper atrophy. While congenital heart disease can lead to various structural heart issues, the specific mechanism cited in the question directly correlates with the pathophysiology of aortic stenosis, making it the most common cause in infants and children.