Congenital Abnormalities Atrial Septal Defect Lesson Waveform Anatomy play pause Table of Contents 1Coarctation of the Aorta 2Patent Ductus Arteriosus 3Atrial Septal Defect 4Ventricular Septal Defect 5Tetralogy of Fallot 6Ebstein's Anomaly Quiz This video is an animation of Atrial Septal Defect A#29 (lesson# 3) within course number 3. This is an auscultation example of an atrial septal defect as heard at the pulmonic position.Atrial Septal Defect is a congenital condition associated with abnormal blood flow between the left atrium and the right atrium. Before birth there is a large connection between right and left atria. During development of the fetus the connection gradually disappears. However, in some cases the opening persists and is known as an atrial septal defect.Both the first and second heart sounds are split. The second heart sound splitting is fixed at 80 millisceconds.There is a brief diamond shaped murmur in early systole and another brief diamond shaped murmur in early diastoleIn the anatomy tab you see an enlarged right atrium and right ventricle. You see turbulent blood flow across the tricuspid valve between the right atrium and the right ventricle (the diastolic murmur). This is caused by blood flow from the left atrium into the right atrium through the atrial septal defect. There is further turbulent flow into the pulmonary artery causing the systolic murmur.