Martinelli E1*, Di Stefano A1, Sapone P1, Padulo F1, Mondino S1, Carlucci R1 and Cotroneo AM2
Received: October 16, 2023; Published: October 27, 2023
*Corresponding author: Elisa Martinelli, Complex Geriatric Unit Maria Vittoria Hospital Turin, Italy
Platypnea-Orthodeoxia Syndrome [POS] is dyspnea and hypoxemia in the upright position that improves in the supine position. Cardiac POS is predominantly caused by congenital interatrial communications [CIC] paired with changes in the thoracic anatomy, allowing orthostatic right to left cardiac shunting. High suspicion, especially with hypoxemia without significant pulmonary disease, that does not easily correct with supplemental oxygen, should lead the clinician to obtain echocardiographic imaging, documenting right to left shunting, typically through a patent foramen ovale [PFO]. Transcatheter closure of the CIC is highly successful in relieving symptoms of dyspnea and resolving hypoxemia in the majority of patients.
Keywords: Platypnea-Orthodeoxia Syndrome; Patent Foramen Ovale; Hypoxemia; Intracardiac Shunts
Abbreviations: POS: Platypnea-Orthodeoxia Syndrome; ASD: Atrial Septal Defect; TTE: Transthoracic Echo-Cardiogram; CIC: Congenital Interatrial Communications; PFO: Patent Foramen Ovale
Platypnea-orthodeoxia syndrome [POS] is a rare condition, characterized by positional dyspnea and hypoxemia, described for the first time in 1949 by Burchell . It is uncommon, and occurs predominantly in the elderly, being more prevalent in women than men . It is characterized by the appearance of dyspnea and desaturation in upright position, relieved by recumbency. It is considered to be caused by a temporary increase in intracardiac right-to-left shunt . Four main causes of POS can be recognised: intracardiac shunt, pulmonary shunt, ventilation-perfusion mismatch or a combination of these [3,4]. POS occurs due to the presence of a right-to-left shunt through a PFO, less commonly through an atrial septal defect [ASD] [2,5]. More rarely, POS can be caused by ventilation/perfusion imbalances of the lung parenchyma, observed in chronic obstructive pulmonary disease, interstitial lung disease, hepatopulmonary syndrome, and pulmonary arteriovenous malformations. POS of cardiac origin can manifest insidiously as worsening dyspnea on exertion over the course of months or years, or with an episode of apparently unexplained acute dyspnea that puts the patient’s life at risk .
Mrs ZD, an 85-year-old woman with a history of hyperthyroidism, arterial hypertension, vascular neurocognitive disorder, previous cerebral ischemic stroke, anxious-depressive syndrome, obesity, presented to our hospital for repeated falls and episodes of disorientation, hallucinations and cyanosis associated with new onset of hypoxemia and dyspnea. She had no history of lung disease or tobacco smoking. Upon arrival in the emergency room, the patient was alert, uncooperative. Her physical examination findings on admission were as follows: diffusely reduced vesicular murmur, rhythmic, paraphonic heart tones and severe hypoxia and cyanosis. Arterial blood gas values were: PH 7.48, pCO2 31, pO2 41, HCO3- 23, Lac 1.42. She required 10L/min of oxygen via face mask to maintain oxygen saturation in the low 90s. On chest x-ray, elevation of the right hemidiaphragm. Contrast- enhanced CT excluded the diagnosis of cerebral infarction, pulmonary embolism, pneumonia, and lung parenchymal abnormalities.
On further evaluation, she was found to have worsening oxygen needs when changing from a lying to seated position and standing up from a recumbent position. The clinical picture was consistent with platypnea-orthodeoxia. A transthoracic echo-cardiogram [TTE] revealed a normal ejection fraction, mid-apical septal hypo-akinesia; grade I diastolic dysfunction, ventricular filling pressures within limits; normal atria and interatrial septum with aneurysm of the oval fossa in the absence of visible shunts; so a TTE with intra-venously administered agitated saline contrast solution was performed and it showed a right-to-left shunt, probably through the patent foramen ovale, in the absence of signs of pulmonary hypertension and excessive dilatation of the right sections of the myocardium (Figures 1 & 2; Video 1).
Considering these results, we concluded that the cause of hypoxia was POS with right-to-left interatrial shunt through PFO. POS can be treated with the closure of the interatrial shunt by thoracotomy or percutaneous cardiac catheterization . Surgical closure of PFO was not performed due to the age of our patient and the clinical general condition, surgical difficulties, and failure to obtain informed consent. For these reasons she was discharged after receiving oxygen, medical therapy and advice about her posture.
The most important clue for diagnosis of POS is the emergence of hypoxia with postural changes. Several previous cases have demonstrated that the increased shunt flow across PFO or ASD with posture changes from supine to upright induce hypoxia . The standing upright position can directly change the anatomical route from the vena cava to an intracardiac defect in a straight line, which increases rightto- left shunt . POS is caused by the coexistence of anatomical and functional abnormalities . Anatomical abnormalities include ASD, PFO, or fenestrated atrial septal aneurysm. However, the presence of only these anatomical factors cannot induce POS because they usually cause left-to-right shunting. In addition, functional factors, such as right hemidiaphragmatic paralysis, pericardial effusion, constrictive pericarditis, emphysema, arteriovenous malformation, pneumonectomy, liver cirrhosis, aortic aneurysm, or elongation changes of shunt flow can determine POS . The causes can be or a hemodynamic phenomenon with an interatrial pressure gradient, or a selective blood flow from the vena cava to the left atrium passing through an intercardiac defect . TTE has low sensitivity for small shunts and so the prevalence of PFO observed in the general population was reported to be lower than that observed by transoesophageal echocardiogram [TOE] [14.9% versus 24.3%] ; this indicates that only TTE can fail the diagnosis of ASD or PFO. POS caused by PFO can be clearly demonstrated by the technique of contrast TOE .
There are previous reports where surgical closure of ASD or PFO were successfully performed [12-14]; however, percutaneous transcatheter closure devices have recently come into use because of their reduced invasiveness and are easy and safe compared with open surgery [11,15].
The pathophysiology of POS is not yet well clarified; however it is believed that age-related mechanical and physiological factors are able to act on a pre-existing congenital interatrial communication, determining a right-left interatrial shunt. This shunt would become more conspicuous with the assumption of the upright position due to the presence of tethering forces capable of making the communication between the two atria wider .
Normally in adults, the pressure in the left atrium is slightly higher than the pressure in the right atrium so, even in the presence of interatrial communications, a right-left shunt does not occur. This shunt becomes evident when the pressure in the right atrium becomes acutely [for example in the case of pulmonary embolism, ventricular acute myocardial infarction, acute pericardial effusion] or chronically [any condition of chronic pulmonary hypertension] greater than that in force in the left atrium . However, in the majority of patients with POS of cardiac origin, the pressure in the right atrium is not elevated [18,19]; this eventuality should therefore not distract from the possible diagnosis of POS.
It should also be taken into account that not all people with atrial septal defect will develop POS. So, what happens in patients suffering from this syndrome? It is not always possible to identify the triggering event, however it is necessary to consider the possibility of POS for every patient with dyspnea and desaturation in orthostatism, especially when the symptoms are poorly responsive to oxygen therapy and are alleviated by assuming the supine position. In such patients, although it may seem absurd to look for a congenital pathology at an advanced age, the presence of atrial septal defects must be firmly investigated. These conditions are in fact often susceptible to treatment percutaneously [transcatheter implantation of a closure device] or surgically with resolution of the symptoms [20-22]. In patients in whom POS is due to extracardiac causes [rarer], depending on the pathogenesis, the treatment may be represented by arterial embolization of pulmonary arteriovenous malformations, surgery/lung transplant and, in cases of hepato-venous syndrome lung in liver transplantation.
The authors sincerely thank the patient, who gave consent for publication of this case report. The authors sincerely thank Doctor Davide Forno, Cardiologist of Maria Vittoria Hospital for the kind and precious collaboration.
The authors declare that they have no competing interests.