Patent foramen ovale is the most frequent remnant of normal fetal communication between the atria in adult population. In most cases, it is clinically silent and therefore detected incidentally, however, it may manifest as transient ischemic attack, cerebrovascular insult,
migraine with aura and rarely as decompression sickness, peripheral embolism and platypnea-orthodeoxia syndrome. It may be accompanied by different structures such as atrial septal aneurysm and Eustachian valve. Their presence is often associated with substantial right-to-left shunt through the patent foramen ovale, more pronounced symptoms and more technically challenging percutaneous closure. Patent foramen ovale is diagnosed by echocardiography and transcranial Doppler. Transesophageal echocardiography is the gold standard for the diagnosis due to its high sensitivity and specificity. It is the only investigation which shows the right-to-left transit of contrast as well as the morphology of the patent foramen ovale and the surrounding structures. It must therefore always be carried out before deciding for percutaneous closure of patent foramen ovale. When a patent foramen ovale is found incidentally, primary prevention is not indicated. Secondary prevention, which includes medical therapy or percutaneous closure of patent foramen ovale, is indicated in patients with previous cryptogenic stroke, recurrent transient ischemic attacks, and peripheral embolism. Generally, percutaneous closure does not significantly reduce the risk of recurrent ischemic event compared to drug therapy; however, it may be beneficial for a selected group of younger patients with high risk for an ischemic event.