There are excellent books out there that talks about Heaven and people who have had NDE’s and who have lived to talked about it.
Evidence of the Afterlife: The Science of Near-Death Experiences"
In it he gives the scientific part about what happened to the patient, and then the patient's story of their NDE.
Fascinating!
There are also many bad books out there on NDE’s and the Heaven Experience.
The most popular one of all was written by a person who the Virginia medical board investigated and fined for his changing medical records to cover up for his operating on the wrong vertebrae.
Assuming that what they witnessed was in fact heaven, the people with NDEs who visited heaven have something in common: they visited heaven but were not permitted to stay, not unlike Elijah and John (of the Book of Revelations).