An ultrasound of the heart is called an “echocardiogram”. It is done to get pictures of the heart and the areas around the heart. Better pictures are sometimes seen if a material called “contrast” is used during the ultrasound. One type of contrast is saline (sterile salt water). When saline is used it is called a “bubble study”. During a bubble study the doctor or nurse will shake the saline water until it forms small bubbles. The bubbles are then injected into the vein through an intravenous line (IV). A bubble study lets us follow the path that the bubbles take through the bloodstream. In a normal heart the bubbles are filtered by the lungs and are seen only on the right side of the heart. If the bubbles are seen on the left side, it shows that there is an opening between the two sides of the heart, which is abnormal. The abnormality can be an atrial-septal defect or ventricular septal defect. The bubble study helps to identify those abnormalities. The bubble study is safe. The bubble solution is easily absorbed in the bloodstream.