AVSD is defined by absence of which structure?

AVSD is defined by absence of which structure?

• A. Absence of atrioventricular septum, resulting in a single common atrium and ventricle
• B. Absence of interventricular septum with a normal atrial septum
• C. Narrowing of the pulmonary valve
• D. Coarctation of the aorta

Answer: (A)

AVSD arises when the atrioventricular septum fails to form, leaving a single common atrioventricular canal that connects both atria and both ventricles. The normal separation between the right and left sides at the AV junction is missing, so the heart ends up with a single common atrium and a single common ventricle, typically with a common AV valve. This embryologic defect reflects defective formation of the endocardial cushions that contribute to the AV septum. It’s distinct from issues like a simple interventricular septal defect, pulmonary valve stenosis, or coarctation of the aorta, which involve other structures.

AVSD arises when the atrioventricular septum fails to form, leaving a single common atrioventricular canal that connects both atria and both ventricles. The normal separation between the right and left sides at the AV junction is missing, so the heart ends up with a single common atrium and a single common ventricle, typically with a common AV valve. This embryologic defect reflects defective formation of the endocardial cushions that contribute to the AV septum. It’s distinct from issues like a simple interventricular septal defect, pulmonary valve stenosis, or coarctation of the aorta, which involve other structures.