system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
A 5-year-old girl is brought to the emergency depament because of difficulty breathing (dyspnea), palpitations, and shoness of breath. Doppler study of the hea reveals an atrial septal defect (ASD). This malformation usually results from incomplete closure of which of the following embryonic structures?
assistant
The correct answer is  An atrial septal defect (ASD) is a congenital defect in the interatrial septum. During paitioning of the two atria, the opening in the foramen secundum (the foramen ovale) usually closes at bih. If this foramen ovale is not closed completely, this would result in an ASD, shunting blood from the left atrium to the right atrium.