Can laughing gas make your heart stop or make you feel like you died?

If you're referring to nitrous oxide as laughing gas it will not cause cardiac arrest. The dissociative feelings you had are common with any central nervous system anesthetic.

Laughing gas, or nitrous oxide, is quite safe.  We use it routinely for many patients undergoing Botox, fillers, and minor surgical procedures.  Most patients develop a "buzz" as if they have had a few margaritas, which makes potentially painful procedures much more easily tolerated.  Occasionally patients fall asleep or feel that they are in a trance for a few minutes.  However, all effects are quite temporary and resolve within minutes of removing the laughing gas.  As far as getting "too much," this is not physically possible with most setups. For example, our machine administers a maximum of 70% nitrous oxide and a minimum of 30% oxygen.  Since the air that we breathe is 21% oxygen, all patients always receive a higher percentage of oxygen while on nitrous oxide than they receive while breathing room air.