What type of congenital heart defect does not shunt blood flow but causes obstruction?

Aortic stenosis is a type of congenital heart defect characterized by an obstruction of blood flow, specifically at the level of the aortic valve. This obstruction can occur due to various factors, including a malformed valve that may be too narrow (stenotic) or consists of two leaflets instead of three (bicuspid aortic valve).

When the aortic valve is narrowed, it restricts the flow of blood from the left ventricle into the aorta during systole, leading to increased pressure within the left ventricle. This is different from defects that shunt blood flow, such as ventricular septal defect or atrial septal defect, where blood is redirected from one chamber to another, either mixing oxygenated and deoxygenated blood or overloading the pulmonary circulation. In contrast, aortic stenosis results directly from a physical blockage, which can have significant consequences on cardiac function, leading potentially to heart failure if the condition is severe and untreated.

Understanding that aortic stenosis does not cause a shunt but rather a significant obstruction helps differentiate it from other types of congenital heart defects, emphasizing the importance of recognizing the distinct hemodynamic consequences associated with each defect.