how do you/ or what does it mean to "swallow your tongue" when you get a heart attack?

Answer 1

No, you can not swallow your tongue. If you become unconscious and are laying on your back, the muscles that control your tongue will relax and the tongue will fall back, blocking your airway. But you can not swallow your tongue.
It is a diagnostic criteria weather a person is having fits/convulsions/epileptic/traffic accidents etc. or not.
Important in first aid.

Answer 2

Swallowing your tongue is a layman's term that simply means that the tongue falls back in the throat when a person is unconcious. They don't actually "swallow" it. When they are unconcious they don't have control of their muscles (especially during a heart attack, seizure, fainting, etc) and the tongue will become limp and fall backward in the throat and block the airway. You can learn regular CPR at the YMCA or any local community center so you can know how to fix this if it happens when you're around.

Good question.