Atrial and ventricular septal defects

At a glance

• ASD is a pre-tricuspid shunt: it loads the right heart with volume and often presents in adult life with breathlessness, AF or a murmur found incidentally.
• VSD is post-tricuspid: small ones are loud and harmless apart from endocarditis; large ones load the left heart and the pulmonary circulation, and are closed in infancy.
• Untreated large shunts cause pulmonary vascular disease and, eventually, Eisenmenger syndrome. Once the shunt reverses, closure is harmful.