Atrial right-to-left shunting causing severe hypoxaemia despite normal right-sided pressures. Report of 11...

Hypoxaemia resulting from a right-to-left shunt occurs in patients with atrial septal defects and high pulmonary vascular resistance, but it is uncommon without pulmonary hypertension.

We report on 11 consecutive patients (age: 59-78 years) in whom a patent foramen ovale or a small atrial septal defect with normal right-sided pressures led to significant cyanosis with clinical symptoms. Six of them had associated platypnoea and orthodeoxia. The diagnosis was confirmed by contrast transoesophageal echocardiography showing an atrial right-to-left shunt.

All but one were successfully treated by percutaneous closure of the inter-atrial defect. In one patient, delivery of the occluder failed due to kinking of the introducing sheath. Four complications were observed following the procedure: two supraventricular arrhythmias and a cerebrovascular accident, all resolved without sequelae; one patient died from a septic shock unrelated to the procedure. During follow-up (up to 30 months), no patient experienced any episode of desaturation due to inter-atrial shunting.

Cyanosis without pulmonary arterial hypertension in the adult should prompt the performance of contrast transoesophageal echocardiography to identify a possible atrial right-to-left shunt. Percutaneous closure of the defect allows efficient and rapid correction of the hypoxaemia and avoids the need for surgical closure.