atrial septal defects

this is a communication between the two atria. it can be high in the atrial septum at the superior vena caval-right atrial junction, a sinus venosus defect; in the region of the foramen ovale, a secundum defect, and in the lower part of the atrial septum, a so-called primum atrial septal defect, which is described under the section on atrioventricular septal defects. with the exception of primum atrial defects, atrial defects are rarely predictable prenatally. the foramen ovale is always widely patent in the fetus and it is the failure of the flap valve to close off this defect postnatally which creates a secundum asd. it appears impossible to predict this prenatally unless the foramen is very large, essentially in the setting of a common atrium. atrial septal defects present during childhood with an asymptomatic murmur and signs of a left to right shunt at atrial level. they are readily successfully repaired surgically with excellent long-term results.