[Patent foramen ovale, stroke, and echocardiography: diagnostic methodology and appropriateness of indications].

A patent foramen ovale is a frequent remnant of embryological development with clinical importance in stroke, decompression sickness, and migraine headache. The proposed mechanisms of stroke include paradoxical embolization, in situ thrombosis within the canal of the foramen, associated atrial arrhythmias. Cardiac right-to-left shunts can be identified by echocardiography and by transcranial Doppler ultrasound with the use of contrast agents and a Valsalva maneuver as provocation procedure. Relative value of different diagnostic tests, appropriate timing of the Valsalva maneuver, use of a diagnostic time window, and threshold in contrast agent microbubbles detection are thoroughly discussed. The value of echocardiography or of other diagnostic tests does not elucidate the effect of test results on patient management. The appropriate use of imaging requires an understanding of both the capabilities of the imaging technique and the value of therapy used to treat the identified condition. New information that does not improve outcome has no value. In patients with a cryptogenic stroke and an atrial septal abnormality the evidence is insufficient to determine whether warfarin or aspirin is superior in preventing recurrent stroke or death, but minor bleeding is more frequent with warfarin. There is insufficient evidence to evaluate the efficacy of surgical or endovascular closure.