How does Hearbeat security work?

That's quite an open ended question but hopefully some of the info you require can be found here:

https://community.sophos.com/kb/en-us/122880

https://vimeo.com/144419337

https://news.sophos.com/en-us/2015/11/09/xg-firewall-security-heartbeat/

https://www.youtube.com/watch?v=DeeKumt9BaE

https://www.sophos.com/en-us/lp/synchronized-security.aspx links to a white paper - "Synchronized Security: Best-of-breed defense that’s more coordinated than attacks"

Regards,

Jak