ABSTRACT
Closure of secundum atrial septal defects (ASDs) is indicated when there are typical clinical signs supported by diagnostic evidence of a significant left to right shunt. Such evidence includes an ECG pattern of rSR splintering in the right sided chest leads, enlargement of the right atrium seen on chest X-ray, and echocardiographic evidence of right atrial and right ventricular volume loading. Dilation of the right ventricle beyond two standard deviations from the mean is also usually associated with abnormal septal motion seen as dyskinesia, sometimes descibed as ‘paradoxical septal motion’. ASD closure is advocated to avoid the long term effects of right heart dilation. These include effort intolerance, atrial tachydysrhythmias, particularly atrial fibrillation, and right heart failure secondary to pulmonary hypertension progressing to pulmonary vascular disease. A very small number of patients with an ASD present with a paradoxic embolic event such as stroke, transient ischemic attack, or systemic arterial embolism. Whilst interventional closure of secundum ASDs with devices is commonplace, surgical closure is still required for very large defects.
