One of the best ways to identify the presence of a hole in the heart, such as Atrial Septal Defect (ASD) or a Patent Foramen Ovale (PFO) is to perform a bubble study.
Normally, the right (low pressure side of the heart) does not communicate with the left high pressure side of the heart. However, in individuals with an ASD or PFO blood can flow from right to left.
What happens during an Echocardiogram
A normal transthoracic Echocardiogram is performed. A small needle will be placed into the vein on the back of the hand. Some sterile saline will then be drawn up into a syringe and agitated so that microscopic bubbles are formed in the saline solution. These are then injected briskly into the vein, whilst the imaging takes place. The right side of the heart (connected to the venous system) opacifies very nicely, as the bubbles show very brightly on the Echocardiogram. You may be asked to strain to encourage bubbles to go across.
Bubble Test Results
No bubbles should be seen on the far side of the heart. However, if bubbles do appear on the left side of the heart, this is a positive test and strongly indicates the presence of a hole in the heart. Your cardiologist will probably then wish to perform a Transoesophageal echocardiogram (TOE) to delineate this and make decisions about whether closing the defect with a device is appropriate.