An infant has a crescendo-decrescendo systolic ejection murmur located between the second and third intercostal spaces along the left sternal border. These findings are consistent with which congenital heart defect?

The presence of a crescendo-decrescendo systolic ejection murmur, particularly in the location mentioned (between the second and third intercostal spaces along the left sternal border), is characteristic of blood flow across the left ventricular outflow tract, often associated with pulmonary stenosis. While atrial septal defect (ASD) can produce some turbulent flow sounds due to increased blood flow through the right atrium and ventricle, the typical murmur associated with ASD is more of a fixed split S2 and is not specifically described as crescendo-decrescendo. Therefore, while ASD can create a murmuring sound, the specific characteristics of this murmur and its location are more indicative of conditions associated with left ventricular outflow obstruction such as pulmonary stenosis, which is not one of the listed choices.

In evaluating the other congenital heart defects presented, a ventricular septal defect (VSD) typically results in a holosystolic murmur rather than a crescendo-decrescendo pattern. An atrioventricular canal (AVC) defect also has a distinct murmur pattern that does not fit the description provided. Finally, patent ductus arteriosus (PDA) usually creates a continuous “machine-like” murmur, rather than