[Clinical relevance of patent foramen ovale and right-to-left shunt]

A frequent finding in healthy individuals, patent foramen ovale (PFO) with right-to-left shunt (RLSh), is an embrionary residue that has been linked with cryptogenic stroke and peripheral ischemia. Pulmonary hypertension and entities like decompression illness, migraine with aura or plathypnea-orthodeoxia have been found to have a higher prevalence of PFO with RLSh. Some dementias and unexplained syncopes could also have some relationship. Paradoxical embolism, thrombosis of the foramen channel or the atrial structures with subsequent embolism, transient arrhythmias, prothrombotic states and vasoactive substances passage have been proposed as physiopathologic mechanisms involved. Contrast-enhanced transesophageal echocardiography is the standard reference diagnostic procedure but contrast-enhanced transcranial Doppler is a good non-invasive alternative diagnostic tool that is highly sensitive and specific.