Clinical ReviewPatent foramen ovale and obstructive sleep apnea: A new association?
Introduction
Obstructive sleep apnea is a common condition affecting 9% of adult males and 4% of adult females.1 It is characterized by repetitive collapse of the pharyngeal airway during sleep, resulting in reduction or complete cessation of airflow despite respiratory effort. Patent foramen ovale (PFO) is also a common condition found in up to 27% of adults.2, 3 PFO is a remnant of the fetal circulation which allows potential communication between the right and left atria and thus provides the anatomical substrate for right to left intracardiac shunting. Given the high prevalence of both PFO and OSA in the population, the co-existence of both conditions in an individual would be a relatively common occurrence. The association between PFO and conditions such as cryptogenic stroke, migraine and decompression illness is well established.4, 5, 6, 7, 8, 9, 10, 11, 12 Recent literature has provided evidence to support a possible link between OSA and PFO. Furthermore, this link may also potentially contribute to the association between stroke and OSA. The focus of the article is to review the current emerging knowledge of the association between OSA and PFO with particular emphasis on 1) epidemiological studies supporting the existence of an association; 2) pathophysiological interactions between the two conditions which may underlie the association; 3) potential clinical consequences and implications in patients who have a co-existence of both conditions; 4) future research agendas in this area.
Section snippets
Patent foramen ovale
Patent foramen ovale is a congenital cardiac lesion which can persist into adulthood. It is a flap-like opening in the atrial septal wall and functions as an essential part of the fetal circulation to allow shunting of oxygenated blood across the atrial septum, thus bypassing the high resistance fetal pulmonary circulation. At birth, a fall in pulmonary vascular resistance and hence right atrial pressure along with a rise in left atrial pressure leads to closure of the PFO, and fusion is
The OSA and PFO association: biological plausibility?
An association between PFO and OSA is supported by epidemiological studies demonstrating a higher prevalence of PFO in the OSA population. Although evidence of a direct causal relationship between the two conditions is lacking, recent studies have demonstrated important pathophysiological interactions between PFO and OSA which may account for their association. We will review the epidemiological data available to date and the possible mechanisms proposed to explain the PFO and OSA association.
PFO and oxygen desaturation burden
Intermittent hypoxia during sleep is the hallmark of OSA. Intermittent hypoxia can activate pathways such as systemic inflammation, oxidative stress, endothelial dysfunction and sympathetic over-activity.26 These important pathways are thought to mediate, at least in part, the diverse cardiac and metabolic consequences of OSA.
As OSA and PFO are both prevalent conditions, the co-existence of both conditions in an individual would be commonplace. It would be expected that the prevalence of PFO in
Conclusion
Recent epidemiological, physiological and clinical studies have provided emerging evidence of a relationship between OSA and PFO. There appears to be a higher than expected prevalence of PFO in OSA patients, and that OSA patients with PFO may be susceptible to greater nocturnal oxygen desaturation during sleep. From a mechanistic viewpoint, an obstructive event can provoke the hemodynamic conditions necessary to favour right to left shunting, with intrathoracic pressure swings and hypoxic
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Cited by (28)
Cardiovascular implications of obstructive sleep apnea associated with the presence of a patent foramen ovale
2014, Sleep Medicine ReviewsCitation Excerpt :The size of PFOs increases with age while the prevalence decreases with age [3]. PFOs may be linked to strokes, transient ischemic attacks (TIAs), migraines, systemic embolism, or decompression illness [1,3,4]. Furthermore, PFO may have an association with obstructive sleep apnea (OSA) [1].
Prevalence of patent foramen ovale and its impact on oxygen desaturation in obstructive sleep apnea
2013, International Journal of CardiologyDramatic improvement in hypoxemic respiratory failure after patent foramen ovale closure in a patient with obesity hypoventilation syndrome
2012, Cardiovascular Revascularization MedicinePatent foramen ovale-obstructive sleep apnea relationships: Pro and cons
2012, Cardiovascular Revascularization MedicineCitation Excerpt :The obstructive sleep apnea syndrome (OSAS) is a common disorder in the middle-aged population [6]. An echocardiographically visible PFO was detected in 27%–69% of patients with documented OSAS [7,8], a clearly higher incidence than in non-OSAS patients, suggesting a relationship between PFO and OSAS, but the pathophysiology of this potential relationship is still unclear. The authors in this brief review attempted to clarify this controversy.
Patent foramen ovale and obstructive sleep apnoea: From pathophysiology to diagnosis of a potentially dangerous association
2011, Archives of Cardiovascular Diseases
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