What are the qualities of an ASD murmur?

An atrial septal defect (ASD) murmur is characterized primarily by being a systolic murmur. This occurs because the left-to-right shunt created by the defect leads to increased blood flow across the pulmonary valve during systole, which generates a typical sound associated with this condition. The murmur is usually described as a "fixed split" S2, which can be an important diagnostic feature.

Additionally, the sound associated with an ASD tends to be soft and may be heard best at the left upper sternal border, but its primary classification is as a systolic murmur, which is crucial for recognizing the defect. Understanding these qualities helps in differentiating an ASD murmur from other cardiac murmurs that might have different characteristics, such as those associated with other congenital heart defects or valvular issues.

Recognizing the nature of the ASD murmur as predominantly systolic distinguishes it clearly from murmurs that are diastolic, pulsatile, or continuous, which have different hemodynamic implications and clinical relevance.