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 characterized 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 transcatheter 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 transthoracic echocardiography, dilatation of the ascending aorta (40 mm) and a mobile atrial septal aneurysm (ASA) were noted. Transcatheter aortic valve implantation 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. Transthoracic 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: Platypnoea-orthodeoxia syndrome 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. Platypnoea-orthodeoxia syndrome should be considered in patients with unexplained hypoxaemia after TAVI.