Where is a split S2 heart sound best heard during auscultation?

A split S2 heart sound is best heard at the second intercostal space, right sternal border. This location corresponds to the auscultation point for the aortic valve and is optimal for detecting the splitting of the second heart sound, which occurs due to the delayed closure of the aortic and pulmonary valves.

The right sternal border is especially pertinent for identifying this phenomenon because it allows for a clearer differentiation between the sounds produced by the valves. The splitting of S2 is typically more pronounced during inhalation, and positioning the stethoscope in this area makes it easier to hear the subtle variations in heart sounds.

While the second intercostal space at the left sternal border is associated with the pulmonary valve and can also demonstrate a split S2, the right sternal border provides a better auditory context for the sounds based on normal physiological variations and helps highlight the differences in closure timing between the two heart valves during auscultation.