Primary Interatrial Foramen - Clinical Significance

Clinical Significance

Failure of the septum primum to fuse with the atrio-ventricular cushion can lead to an ostium primum atrial septal defect. This is the second most common type of atrial septal defect and is commonly seen in Down's syndrome. Typically this defect will cause a shunt to occur from the left atrium to the right atrium. Children born with this defect may be asymptomatic, however, over time pulmonary hypertension and the resulting hypertrophy of the right side of the heart will lead to a reversal of this shunt. This reversal is called Eisenmenger syndrome.