Platypnoea-orthodeoxia syndrome following transcatheter aortic valve implantation complicated by aortic annular rupture: a case report

Background Platypnoea-orthodeoxia syndrome (POS) is a rare disorder characterised by dyspnoea and hypoxaemia occurring while upright and improving while recumbent, most often caused by inter-atrial shunting. Diagnosis is challenging, and the syndrome carries considerable morbidity if left untreated. In patients with inter-atrial communications such as a patent foramen ovale (PFO), haemodynamic and structural changes occurring after trans-catheter aortic valve implantation (TAVI) can lead to platypnoea-orthodeoxia. Case Summary A 77-year-old patient with severe aortic stenosis was referred for TAVI at our institution. On trans-thoracic echocardiography, dilatation of the ascending aorta (40mm) and a mobile atrial septal aneurysm (ASA) were noted. TAVI was complicated by annular rupture and aortic intramural haematoma (IMH), managed conservatively. Three weeks after discharge, the patient re-presented with cholecystitis and underwent cholecystectomy. Post-operatively, marked hypoxaemia was noted during orthostasis. Trans-thoracic echocardiography showed the ASA bulging into the left atrium, with a strongly positive saline contrast study while upright. A PFO was identified on transoesophageal echocardiography and successfully percutaneously closed, with hypoxaemia resolving. Discussion POS is a rare complication of TAVI, not previously reported after annular rupture. Aortic dilatation is often implicated in platypnoea-orthodeoxia, likely by compressing the interatrial septum and potentiating right-to-left shunting. In our patient, with a mildly dilated aorta prior to intervention, annular rupture and IMH may have further distorted atrial anatomy. Furthermore, rapid improvements in left ventricular compliance and left-sided filling pressures after TAVI may have facilitated the new onset of right-to-left shunting. POS should be considered in patients with unexplained hypoxaemia after TAVI.