Hello aunt scripty, this may be a really dumb question because it may or may not exist, but has there been a case of anyone that lived with two hearts? If so how do you think it would work? How would it work during CPR/etc? Would having two hearts hinder anyone? Would it pump too much blood because of two hearts!? (Doctor Who, amirite?) Haha... nope, jk, as much as I'm a fan, I'm just asking out of pure curiosity.
Okay, this ask is really, really cool. Thank you for this!
So there are two ways this comes into being.
One is a birth defect. The only report I was able to find of someone being born with two hearts is a guy by the name of George Lippert, who also had three legs. (The third leg had 6 toes, for a total of 16. The things I have learned for making this blog.) At autopsy it was discovered that he had two hearts as well, which…. Sure! That said, this was all in the 19th and very early 20th centuries, so we have no idea if a) it was true or one final prank/an attempt to make some cash by his family or doctors; b) the second heart worked or, like the third leg, if it was just…. there and useless. It was never studied or even discovered in vivo, so we don’t know how it worked.
It’s likely that he basically absorbed his twin in the womb but was left with some, well, leftovers. This is called a parasitic twin.
The other thing I’ve heard of regarding a human with two hearts is… adding a second heart.
There are two types of transplants: orthotopic transplants, in which an organ is straight-up removed and replaced, and a heterotropic transplant, in which a weak-but-still-functioning organ is augmented by adding in an extra. Sometimes this is done with kidneys, but occasionally, we graft a second heart into a human and send them back into the wild.
So there was a phenomenal case of a guy showing up to an Italian ER in cardiogenic shock from his two hearts having conflicting rhythm. He coded, got zapped, got a new pacemaker, and left the hospital. Dude was apparently 71, which is kind of badass: 71, two hearts, and death can’t touch him. This guy is clearly an action hero in the making.
Sometimes, the person recovers enough not to need their second heart anymore.
Hannah Clark is a teenager in South Wales who had serious cardiac complications when she was just a baby, had a second heart grafted in, and then had it removed when she was 16. She was suffering immune complications from the grafted tissue, and her native heart had had the time to grow strong enough to carry her itself. She’s the first person in the UK to have a transplant reversed.
In the heterotropic grafts, it seems like what happens is that the transplanted heart’s rhythm is basically paired to the native heart’s, so that one almost paces the other.
As for CPR, it’s unaffected by the number of hearts. Like our Italian man, your character might run into trouble if the two hearts beat at different rates.
This is an area of fiction where you can kind of make up what you want, because the two hearts idea functionally breaks the Rule of Reality. Just remember that if they were born with two hearts, they have to work together long enough and well enough to get that character out of the womb and into the world and raised to (whatever age they’re at), so however the system works at baseline, it has to work (at least until it goes wrong).
So best of luck with your story!!