New aspects of paradoxical embolism.

Paradoxical emboli have their origin in the low-pressure venous system and can cause ischemic stroke or peripheral arterial embolism through a cardiac or pulmonary shunt. In most cases, a patent foramen ovale (PFO) is found. About 20 % of the population has a patent foramen ovale. This review gives insight into publications concerning the association between the presence of a patent foramen ovale and cryptogenic stroke; the association of PFO, coagulation disorders and stroke; and recurrence rates of stroke in patients with PFO. Diagnostic features are discussed, as are the different therapy modalities, taking existing national and international guidelines into account. Also, our own recommendations are given. In addition some new information on the potential improvement of migraine after PFO closure is discussed. It is widely accepted that the optimal therapy for the prevention of recurrent stroke in patients with PFO and cryptogenic stroke has not yet been found. Randomized, controlled clinical studies are ongoing in the United States and will give even more insight and answer open questions in the future.