Which congenital heart defect is characterized by an abnormal connection between the left and right atria?

An atrial septal defect is characterized by an abnormal connection between the left and right atria, resulting from a failure of the septum that separates these two chambers to completely form. This defect allows blood to flow from the left atrium, where pressure is typically higher, into the right atrium. This shunting of blood can lead to increased blood volume in the right atrium and right ventricle, which may ultimately cause complications such as right heart enlargement, pulmonary hypertension, or atrial arrhythmias if left untreated.

In contrast, a ventricular septal defect involves an opening between the ventricles, not the atria. Coarctation of the aorta is a narrowing of the aorta, which does not involve the atrial chambers directly. Patent ductus arteriosus refers to the failure of the ductus arteriosus to close after birth, creating an abnormal connection between the aorta and the pulmonary artery, also unrelated to the atrial septum. Understanding these distinctions is crucial for identifying and managing pediatric congenital heart defects.