What congenital malformation presents as an opening between the atria?

An atrial septal defect is a congenital malformation characterized by an opening in the atrial septum, which is the wall dividing the left and right atria of the heart. This defect allows blood to flow from the left atrium to the right atrium, as there is typically higher pressure in the left atrium, leading to increased blood volume in the right atrium and right ventricle.

This condition can lead to various complications, such as right heart enlargement and pulmonary hypertension over time, as the increased blood flow can strain the right heart and the pulmonary circulation. The atrial septal defect is often asymptomatic in childhood but may present symptoms later in life, including fatigue or palpitations.

Other options refer to different types of cardiac anomalies; for example, a ventricular septal defect involves an opening in the septum between the ventricles, which has different hemodynamic effects. An endocardial cushion defect affects the common atrioventricular canal, involving both atrial and ventricular septum abnormalities along with valve issues. Mitral valve prolapse relates to the improper closure of the mitral valve rather than an opening between the atria. Thus, the specific description of an opening between the atria directly corresponds to