100% of people found this usefulThe gold standard test is a Transoesophageal Echocardiogram (TOE). An ultrasound probe is swallowed so that it is positioned behind the heart in the gullet. A peripheral vein is canulated and an injection of 'agitated saline' is made into the vein. The agitated saline contains thousands of tiny bubbles which show up as bright spots on the echocardiogram screen when they pass through the right side of the heart.
By getting the diver to perform a Valsalva manoeuvre (like an exaggerated ear clearing), bubbles may be forced through a patent PFO into the left atrium.
It should be noted that the usefulness of this test depends upon the skill and experience of the clinician doing the test. Several large PFO's have been missed on first testing by inexperienced doctors.
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