What type of defect does the term "atrial septal defect" refer to?

The term "atrial septal defect" refers specifically to a hole in the septum that divides the heart's two upper chambers, known as the atria. This condition allows blood to flow improperly between the left and right atria, which can lead to increased blood flow to the lungs and pressure in the pulmonary circulation.

Atrial septal defects can vary in size and may not always cause symptoms, particularly in mild cases. However, if the defect is significant, it can lead to complications such as heart enlargement, arrhythmias, and heart failure if left untreated. Understanding this defect is crucial for diagnosing and managing congenital heart conditions effectively.

In contrast, the other choices describe different cardiovascular issues: narrowing of a valve pertains to stenosis, blockage in the coronary arteries refers to coronary artery disease, and malfunctions in the heart's electrical system describe arrhythmias. Each of these conditions is distinct from an atrial septal defect and involves different mechanisms and treatments.