Echocardiography is a scan that uses ultrasound (sound waves) to produce pictures of the heart. The Bubble Study involves a small amount of micro bubbles being sent to the heart via a vein to watch how they travel through the heart. If you have a hole between the left atrium and right atrium (patent foramen ovale), some bubbles will appear on the left side of the heart. The test informs the doctor whether there are any congenital defects affecting the chambers of the heart. The test requires putting a small cannula in your vein. It does not use radioactivity and is without side effects.