Ramana Maharshi shares his experience of (temporarily) dying, in which he had a direct understanding of the location of the Heart Center:

I had been saying all along that the Heart centre was on the right, notwithstanding the refutation by some learned men that physiology taught them otherwise. I speak from experience. I knew it even in my home during my trances. Again during the incident related in the book Self-Realisation I had a very clear vision and experience. All of a sudden a light came from one side erasing the world vision in its course until it spread all round when the vision of the world was completely cut out. I felt the muscular organ on the left had stopped work; I could understand that the body was like a corpse, that the circulation of blood had stopped and the body became blue and motionless. Vasudeva Sastri embraced the body, wept over my death, but I could not speak. All the time I was feeling that the Heart centre on the right was working as well as ever. This state continued 15 or 20 minutes. Then suddenly something shot out from the right to the left resembling a rocket bursting in air. The blood circulation was resumed and normal condition restored. I then asked Vasudeva Sastri to move along with me and we reached our residence.

Image by G. G. Welling, 1948 [Public domain], via Wikimedia Commons