An uncommon complication of an aortic root aneurysm

Abstract

Platypnea-orthodeoxia syndrome (POS) is an uncommon clinical syndrome consisting of dyspnea and deoxygenation accompanying a change from a recumbent to an upright position. The underlying mechanism requires both anatomical and functional features, which result in a right-toleft interatrial shunt. We present a case of POS in an elderly patient with patent foramen ovale (PFO) and aortic root dilatation. A 79-year-old woman, with a history of a healed breast cancer 30 years before, was admitted to the emergency room with increasing dyspnea and shortness of breath last month, especially when moving from supine to the erect position. On physical examination, in a recumbent position, she was eupneic, well perfused and her arterial blood oxygenation was 94 %. When standing up, she referred dyspnea and developed peripheral cyanosis with an arterial blood oxygenation of 63 % despite oxygen administration. On auscultation, a diastolic murmur of aortic regurgitation was heard. A chest X-ray showed dilatation of the aortic root without signs of heart failure. The electrocardiogram did not show abnormalities. An urgent transthoracic echocardiogram was performed revealing normal ventricles, moderate aortic regurgitation and the presence of a dilated ascending aorta and aortic root (48 mm) which compressed extrinsically the right atrium with a significant chamber reduction. Estimated systolic pulmonary pressure was 37 mmHg. An interatrial septum aneurysm was observed, and when agitated saline was injected intravenously in a lying position (Fig. 1a), no microbubbles were identified in left atrium. Nevertheless, when standing up, the aortic root compressed sharply the right atrium, and microbubbles appeared immediately in the left atrium (Fig 1b.), confirming the existence of a right-to-left intracardiac shunt. A CT scan proved dilatation of the aortic root with severe compression of the right atrium without signs of intrapulmonary arteriovenous malformations. The patient underwent closure of the PFO with a percutaneous device (Fig 1c). During the procedure, an aortography was performed showing the ascending aorta and aortic root dilatation and enabling its measurement. There was no evidence of right-to-left residual shunt in the echocardiographic control one week later. The patient was discharged and two years later remains asymptomatic. POS is a rare underdiagnosed clinical entity, first described by Burchell [1], consisting of dyspnea and hypoxemia induced by upright posture that is relieved by recumbency [2]. Its pathophysiology is controverted and has been related to hepatic, pulmonary and cardiac diseases. Nowadays, the most recognized underlying condition is the presence of a right-to-left interatrial shunt in the presence of a PFO or an atrial septal defect (ASD) [3]. In normal circumstances, due to the higher pressure of the left atrium, in the presence of either a PFO or an ASD, there is left-to-right shunt. When conditions that increase right atrial pressure and modify the position of the atrial septum concur, redirection of the flow from the vena cava towards the septum in the upright posture is possible. These conditions can be cardiac (pericardial effusion, constrictive pericarditis), pulmonary (arteriovenous malformations), hepatic (cirrhosis) or vascular (aortic aneurysms) in origin [2–4]. J. M. Montero Cabezas (&) M. de Riva Silva R. Martin Asenjo F. Hernandez Hernandez 12 de Octubre University Hospital, Madrid, Spain e-mail: jmmonterocabezas@hotmail.com