Try contacting the Suzy Lamplugh Trust as they might know of organisations that could help. Offhand I can't think of any though some have a live link to a call centre operator and can record conversations etc and use GPS tracking so emergency services can locate the person. What type of work is the employee undertaking? Do they have a pre-existing heart condition that needs to be monitored hence the requirement for heartbeat detection? just curious as if the do have a pre-existing condition that may result in their demise, should they really be working on their own if there is a higher probability of them having an attack?

Not sure if they will have devices for detecting heart beats but I have used http://www.peoplesafe.co.uk/ for lone worker devices in the past, give them a call.

I think most lone worker devices such as Yellow Brick certainly don't have that facility. But they do have a lost communications facility along with the ability to send text messages.

Good luck with your search.

With nearly everyone in the UK having a smartphone you could look at one of the numerous Paid for Apps for Lone workers, Not only would they be able to "Check in" at certain times but you will be able to "Keep Tabs" on them via GPS and Google maps, Some even incorporate a "Panic Button" as a feature.

Ideally for those workers that travel around as part of their job