Final answer:
The right atrium is the structure most commonly at risk during the surgical correction of an ASD, due to its connections and proximity to vital vessels and heart structures.
Step-by-step explanation:
During the surgical correction of an Atrial Septal Defect (ASD), the structure most commonly at risk of intraoperative injury is the right atrium. The right atrium receives blood from the systemic circuit through vessels such as the inferior vena cava and the coronary sinus. It is closely associated with structures like the fossa ovalis, the tricuspid valve, and nearby coronary arteries including the right coronary artery and the posterior interventricular artery. Care must be taken to protect these components, particularly the right atrium itself and its associated vessels and valves, to prevent complications.