I have assisted with numerous TEE's.(Transesophagealechocardiograms)
An IV sedation is used such as Versed, Demerol, Diprivan or Morphine or a combination of these - but not all of them.

The patient is laying on his side, a bite block is placed in his mouth (to keep you from inadvertantly biting the tube and allowing your teeth to rest upon something while the scope in your mouth) and the back of his throat is sprayed with a numbing medication. The scope is a
good bit smaller than the diameter of my Buzz; that's the best I can offer since I can't show you my finger, lol.
The scope uses ultrasonic waves and is easily passed via the mouth into the esophagus - into the area where the heart is the closest. The screen in the room is a live action image and is recorded - the patient is usually awake enough to watch, but not always enough to remember.
The patient is kept comfortable throughout the procedure with additional medications as necessary as well as having a nurse, a tech, the sonographer and the physician at bedside. It generally takes 15 minutes from start to finish - if that long.
The half life of the sedatives are fairly short - and you will come around quickly - possibly being ready to go home within an hour of having the procedure completed. However, these meds have a rebound effect on some individuals and effect each person differently and you will not be able to drive, etc. until the next day.
Versed (midazolam) is infamous for amnesiac effects. You may not remember a thing, TT, even though you are walking, talking and drinking prior to discharge.
These folks are pros - it won't be anything near as uncomfortable, as risky, or as lengthy as heart catheterization.