Stroke is a devastating condition that leads to disability. Following a stroke, tests are conducted to identify condition where preventive measures can be instituted to reduce recurrence.
One such test: Bubble Contrast Transcranial Doppler TCD is a particularly useful test in diagnosing certain conditions, such as a patent foramen ovale (PFO), which is a small hole between the heart’s upper chambers. This hole can allow blood clots or other substances to travel from the veins to the arteries, potentially leading to strokes or other problems.
In this test, a contrast agent, typically tiny bubbles, is injected into a vein, usually in the arm. These bubbles are very small and harmless. As the bubbles travel through your bloodstream, they pass into the heart. In a structurally normal heart, these bubbles stay within the right side of the heart and subsequently travel to the lung where they are filtered. If a PFO (or defect) is present, the bubbles can cross through this defect and make their way into the blood vessels of the brain. (Video 1). This bubble imaging mimics the pathway of clots which can travel in the same fashion to the brain, occluding
the arteries and causing stroke.
A technician places an ultrasound detector on the surface of the head which can detect these bubbles as they pass through the blood vessels in your brain. We call these HITS (high-intensity transient signals).