What Is Atrial Septal Defect (ASD)?

Atrial septal defect is the presence of an opening in the atrial septum.  It may be due to the failure of the foramen ovale to close.  Defects in this region of the atrial septum account for 9 – 10 % of all lesions.  Blood flows across the defect from left (high pressure) to right (low pressure) and causes increased pulmonary blood flow.  The increased volume and workload result in right sided hypertrophy and possibly mild to moderate pulmonary edema.  This defect is seen more frequently in females.

The signs are usually asymptomatic; may have audible systolic ejection murmur at left sternal border; mild exercise intolerance; mild to moderate cardiomegaly with pulmonary vascular disease gradually increasing.

Atrial septal defects are diagnosed with ECG which reveals atrial arrhythmias (prolonged P – R interval); CXR reveals pulmonary vasculature, prominent pulmonary artery and right ventricle and atrium; echocardiogram reveals abnormal septal motion, allows for visualization of ASD; angiography shows ASD; cardiac catheterization reveals increased O2 saturations in right atrium.   

Medication
Administer digitalis and diuretics if right or left ventricular failure occurs; administer antibiotics post operatively.
Treatment
It may close spontaneously; monitor for signs of complications.
Surgery
Surgical repair is performed only if the defect is large or causing symptoms in boys and should always be repaired in girls due to the high risk of paradoxical emboli in pregnancy.