I had a pacemaker implanted in mid 2016 at age 29, after suffering from an undiagnosed heart condition for around 4 years. It'd always start by me getting a sense of deja vu before becoming dizzy, pale and a little sweaty. I'd then pass out and come to after between 20 and 60 seconds.
I was admitted to hospital after collapsing in a chip shop and hitting my head against the metal bar. A night in hospital left me incorrectly diagnosed with epilepsy. Always question junior doctors!
After a couple years neurological and cardiological testing, the doctors still didn't know what caused it, but recommended I have a device implanted in my chest to recored my heart when these episodes occur.
It was about 6 months after having that put in that I learned what would happen. When I'd pass out, my heart rate would drop to around 30 beats per minute, before stopping completely. It would then remain that way for the 20 to 60 odd seconds, and then it would almost reboot itself and me. The human body is really remarkable.
After learning this, my cardiologist fitted me with a pacemaker that begins pacing when my heart rate falls to 50 bpm. The device then sends electricity to my heart to pace my heart rate back to a more normal 60 to 70 bpm.
Almost two years on, it seems to have done the job. The reason behind why it happens however is still unknown.