Definition, Etiology, PathogenesisTop
In fetal circulation the foramen ovale provides the necessary anatomical and functional communication between the right and left atriums. The foramen ovale closes after birth in ~70% of people due to increased left atrial pressures; in the remaining individuals, it remains patent, which is considered a normal anatomical variant.
A patent foramen ovale (PFO) can cause an interatrial, mainly right-to-left shunt, which can predispose to paradoxical embolism, orthodeoxia-platypnea syndrome in susceptible patients, and decompression sickness in divers. The role of PFOs in pathophysiology of migraines is not well established, however its association has been implicated in a number of studies.
Clinical Features and DiagnosisTop
The presenting feature may be stroke or a transient ischemic attack, usually in young persons. There is occasional imaging evidence of cerebral embolization without the presence of symptoms. PFOs can be diagnosed using transthoracic echocardiography (with Doppler imaging); the sensitivity of detection can be increased using agitated bubble contrast injection with imaging at rest and with the release phase of the Valsalva maneuver. However, the gold standard for detection of a PFO remains transesophageal echocardiography with bubble contrast injection at rest and with the release phase of the Valsalva maneuver.
1. In the event of recurrent central nervous system embolism in younger individuals and in the absence of other etiologies after a comprehensive evaluation that should include assessment of thrombophilias, the patient can be referred for percutaneous PFO closure, particularly in the case of coexisting atrial septal aneurysm or large right-to-left shunt observed on transesophageal echocardiography.
2. Antiplatelet treatment and prevention of infective endocarditis is necessary for up to 6 months after device closure of a PFO.