system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do pacemakers know the heart rate needs to increase or decrease to keep the right pace, instead of just being a constant rate?
gpt
Asked a pacemaker rep this just a few weeks ago. A lot of the older models didn’t change their rate, so patients had to make sure they didn’t exert themselves too much. Sucks, but beats dying. Some people’s hearts still have a natural pacemaker that works, it’s just that the signal isn’t getting to where it needs to go. So the pacemaker picks up that signal, and copies it with implanted wires to where it needs to go. Some people have no working natural pacemaker. So the newer ones can sense increased activity. The rep said it kind of works on the same idea as a Fitbit. When it detects increased activity, it ups the pace.