What symptom might indicate the need for an evaluation of potential atrial septal defect?

Unexplained fatigue during exertion is a significant symptom that can indicate an atrial septal defect (ASD). This condition occurs when there's a hole in the wall (septum) separating the heart's upper chambers (the atria), which can lead to mixed oxygenated and deoxygenated blood. When individuals with an ASD engage in physical activity, the increased workload on the heart can result in an inadequate supply of oxygen-rich blood to the body, leading to fatigue. The body struggles to meet its oxygen demands, which manifests as tiredness or fatigue during exertion, making it a vital sign for potential heart-related issues.

In contrast, while frequent headaches, excessive sweating, and a persistent cough can be indicative of various health problems, they are less specific to the symptoms associated with an atrial septal defect. Headaches may arise from numerous causes unrelated to heart conditions, excessive sweating could be attributed to anxiety or other non-cardiac issues, and a persistent cough is commonly linked to respiratory conditions. Hence, fatigue during exertion directly correlates with the physiological processes influenced by an atrial septal defect, making it the most relevant symptom in this context.