Synopsis
Distinguish haemodynamically important atrial septal defects from a usually incidental PFO and route closure decisions through specialist congenital or stroke services.
- A secundum ASD is a true deficiency of atrial septal tissue; a PFO is a flap-like persistence of fetal communication and usually has no resting shunt.
- A significant ASD produces right-atrial and right-ventricular volume loading, often with a wide fixed split second heart sound and pulmonary flow murmur.
- A PFO is common and usually incidental; do not assume causality after stroke until alternative mechanisms have been excluded.
Key red flags
Cyanosis, clubbing and advanced pulmonary hypertension suggest right-to-left shunting and make routine closure dangerous.
Investigation priorities
Identify right-heart effects and atrial arrhythmia.
Management branches
Murmur, right-heart dilatation, unexplained hypoxaemia or incidental septal communication.
- Confirm anatomy and physiology with expert echocardiography rather than labelling every communication a PFO.
- Assess symptoms, oxygen saturation, rhythm, right-heart size, pulmonary pressure and associated anomalous veins or valves.