Original articlePlatypnea–orthodeoxia syndrome in the elderly treated by percutaneous patent foramen ovale closure: A case series and literature review☆
Introduction
Platypnea–orthodeoxia syndrome (POS) is a rare clinical phenomenon, associating normal oxygen saturation in the supine position (= platypnea) and arterial oxygen desaturation in an upright position (= orthodeoxia) [1]. The exact underlying mechanisms leading to this unusual condition are not fully understood, but most probably derive from one of the following three categories: intracardiac shunting, pulmonary vascular shunting, ventilation–perfusion mismatch or a combination of these mechanisms [2].
One of the typical issues associated with cardiac POS is the presence of an intracardiac right-to-left shunt through a patent foramen ovale (PFO) [3]. The PFO may remain clinically silent for decades, but when the right–left pressure equilibrium is challenged (e.g. after acute pulmonary injury) or when the heart–lung anatomy is distorted and redirects venous blood toward the PFO (e.g., after pulmonary surgery) [4], [5], [6] it may abruptly manifest itself by the development of POS.
Another known but atypical clinical scenario for cardiac POS is an increase in pulmonary vascular resistances and right ventricular and atrial pressures following pulmonary embolism (PE) which has subsequently opened the PFO and favored the right to left shunt. Since there is a physiological orthostatic increase in intrathoracic pressures [7], this phenomenon is accentuated in an upright position.
To correctly establish the diagnosis of POS, an arterial oxygen desaturation (i.e. < 95% while breathing ambient air) in an upright position needs to be observed, while measuring normal saturations in the supine position. Usually these positional arterial oxygen evaluations are performed using a standard pulse oximeter, which in stable patients correlates well with invasive blood-gas analysis [8], [9], [10].
Additionally, contrast echocardiography, invasive heart catheterization and thoracic computer tomography (CT)-scan are all used to identify the mechanisms leading to POS, to exclude other causes of hypoxemia as well as to locate and quantify the right-to-left shunt.
Presently, the only treatment to reduce the amount of de-oxygenated blood to the left heart chambers is to eliminate the shunt by surgical or percutaneous procedures, since neither pharmacological approaches nor changes in lifestyle have proved effective [11].
The following report describes five patients presenting with cardiac POS, the challenges of the diagnostic evaluation, as well as the positive outcomes obtained after percutaneous PFO closure and in addition it reviews current literature on the subject.
Section snippets
Materials and methods
From a prospectively maintained PFO database of 224 patients in whom PFO was percutaneously closed at our tertiary university hospital, we identified five patients between December 2002 and December 2012 with symptomatic cardiac POS (2.2%). Before considering these patients for PFO closure, they were evaluated by trained cardiologists and pneumologists who excluded other possible etiologies of dyspnea and hypoxemia, notably PE and other lung or cardiac diseases. All patients were investigated
Patient no. 1
Following knee surgery, an 83 year-old woman was referred for recurrent episodes of severe hypoxemia when in an upright position. The pulmonary work-up excluded PE and other parenchymal diseases. Standard TTE was normal, notably without any signs of pulmonary hypertension (PH), but contrast TEE revealed a large PFO associated with an atrial septal aneurysm (ASA) and a significant right-to-left shunt at rest, increasing during Valsalva. Cardiac catheterization confirmed normal pulmonary pressures
Discussion
POS is rarely diagnosed and its prevalence in the general population remains unknown [14]. Accordingly, only isolated case-reports and a few case-series have been reported so far, suggesting that POS may be largely under-diagnosed and/or under-reported [15]. The diagnosis of POS is difficult and our case-series confirms that in patients presenting with respiratory symptoms, POS is usually a “rule-out diagnosis” suspected only at the end of an extensive and non-standardized medical work-up. Once
Conclusions
Platypnea–orthodeoxia syndrome is a rare and complex clinical phenomenon that must be actively screened in the presence of unexplained positional hypoxemia. POS can be divided into three categories according to the underlying pathophysiological mechanism (i.e., intracardiac shunting, pulmonary vascular shunting or ventilation–perfusion mismatch). To confirm the diagnosis of cardiac POS, contrast TTE ± TEE must show the presence of a right-to-left shunt and orthodeoxia must be demonstrated with
Conflict of interests
No disclosure to be reported for the authors. There was no industry funding for this article.
Learning points
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Platypnea-orthodeoxia syndrome is a rare, complex and underdiagnosed clinical phenomenon.
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POS must be actively screened in the presence of unexplained positional hypoxemia.
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Percutaneous PFO closure should be considered the treatment of choice for cardiac POS.
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PFO closure immediately leads to significant improvement of hypoxemia and patient symptoms.
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The authors have no commercial associations or sources of support that might pose a conflict of interest.