In the US legal system, judicial decisions create legal precedents that guide judges in deciding similar future cases. The decisions of the highest court in a jurisdiction create mandatory precedent that must be followed by lower courts in that jurisdiction.
Usually a bubble echo is looking for an opening between the top 2 chambers in the heart. During a regular echo, which is totally noninvasive, they inject some saline with a small amount of air into an IV. That is the only invasive part of the test. They then look at the screen and see where the bubbles go. In a negative study, they all go over to the left side of the heart. In a positive study, some don't go to the left side, indicating a possible connection or small hole in the heart. It is totally painless; I have had 2 done.
There are several types of echocardiograms: Echocardiogram with bubble study: A bubble echocardiogram is the same procedure as an echocardiogram, except an IV is placed in the patient's arm. During certain portions of the imaging, saline with bubbles is injected into the vein.