Should one use echocardiography or contrast transcranial Doppler ultrasound for the detection of a patent foramen ovale after an ischemic cerebrovascular accident?

Patent foramen ovale is frequently associated with embolic cerebrovascular accidents. The diagnosis of patent foramen ovale is easier since the advent of transesophageal echocardiography. However, this method is semi-invasive and is not readily available in all units. Contrast transcranial Doppler ultrasound enables the detection of the passage of a contrast material injected into a peripheral vein to the cerebral circulation across an orifice which is most often a patent foramen ovale. Contrast transcranial Doppler ultrasound may facilitate, with a high sensitivity and specificity, the diagnosis of a patent foramen ovale when a transesophageal echo is not possible. However, transesophageal echocardiography remains the preferred test especially in the young since other potentially embolic sources, such as a thrombus in the left atrium, may be demonstrable.