Which physical finding is commonly associated with an atrial septal defect?

The physical finding that is commonly associated with an atrial septal defect is a fixed split S2. In individuals with an atrial septal defect, the left-to-right shunt causes increased blood flow to the right atrium and subsequently to the right ventricle and pulmonary arteries. This increased volume leads to prolonged right ventricular systole, which causes the second heart sound (S2) to split and remain fixed regardless of the timing of respiration. This is a classic auscultatory finding in patients with atrial septal defects.

The other findings typically do not correlate with atrial septal defects. Increased pulse pressure is more often associated with conditions that affect arterial compliance or volume status rather than a simple septal defect. A continuous mechanical murmur is suggestive of a patent ductus arteriosus, while a difference in blood pressure between the arms can indicate coarctation of the aorta or other vascular anomalies, but is not a feature of an atrial septal defect.