3d ago

Would having two hearts be better or worse for the human body?

Let's imagine that organs can be perfectly grown in a lab and installed into a body without any chance of rejection or other complications usually associated with organ transplant.

You, a perfectly healthy adult human, go to the doctor and have them put a second heart in your chest that is connected to the circulatory system with your original heart.

What would be the effects of this? Could it even be done in this hypothetical situation at all?

31 comments

It’s better, which is why we already do.
Mammals have a double circulatory system, with the left and right ventricles effectively acting as separate hearts that happen to be physically connected.
- Citation needed. The junctions in cardiac cells make electrical signals propagate through them all, so acting independently isn’t something that’s normal. There’s two loops, but one pump. It’s a single system.
  
  Even if they were physically separated you’d want them to pump in sync, to maximize the pressure. So having them share electrical signals is just the optimal setup for two hearts.
  
  You're being needlessly pedantic
  The reality is that they're two hearts
  If they were to be carefully separated, but with the SA & AV nodes still connected somehow (ignoring the fact that the Perkinje fibres and bundle of hiss can also act as pacemakers), you'd have two separate hearts doing their thing

You'd also have to solve the problems of them working with each other instead of against each other.
What happens to your blood pressure? Do they beat at the same time then how do you mitigate the pressure spike. You now have twice the capacity your blood vessels are meant to handle.
If they don't beat at the same time how do you make sure blood does not just go back and forth between the hearts, but actually does something useful?
- If they're in series the pressure will increase, if they're in parallel the flow would increase. Just have a pacemaker organ connected to both to time the pumps. You could reduce blood pressure but increase the amount of blood flowing, therefore less wear and tear on the hearts, arteries, organs, etc.
- Not a hole Keisha. A VALVE.

- Adequately pressurized doesnt seem like a problem here, over pressurization does seem like an issue, the body is very good at self regulation.
  If you had 2 hearts, i can imagine each heart only needing to work half as hard to keep a person alive, except for times when the blood vessels themselves become "unnaturally" over pressurized, such as the case of regularly high blood pressure, then both hearts have to work harder, regardless of how many hearts you have.
  I dont theoretically see an issue with 2 hearts

- i was gonna say, there have been a couple times my vision got grey and i thought i was going to pass out, but i just pumped my legs for 10 seconds and i was fine.

Perfectly healthy? Probably the only real advantage is redundancy, but that comes at the cost of complexity, and on balance, I’d guess that it’s a net negative.
Mostly because I can’t think of any organism that normally has 2 hearts. If there were real advantages, it seems, I dunno. Inevitable?
- Pretty sure giraffes have 2 hearts, I think the brachiosaurus also had 2 hearts too. I have a feeling there was a fish or other ocean creature with multiple hearts and maybe another mammal?
  Heres some info I found real quick. No giraffe, several sea creatures, a couple land animals, one dino maybe, and some vague ambiguity.
  
  Giraffes are mammals and only have 1 heart. It's freaking huge, though, at 11 kilos.
  octopus and cuddlefish and similar frequently have multiple "hearts" but they're not the same as mammalian hearts. Briachiosaurus probably had an even larger heart than a giraffe, but it was still a singular, 4 chambered hear.

I dont think it will be beneficial. It w would probably cause hypertension. And it's not like bodies have a lot of extra space now where you can fit a heart, so you'd be suppressing other organs.

As others have pointed out the issues, I will answer a different question.
It would be cool to have a backup heart. It sits unused and quite until needed. Clearly some issues with experiencing the same conditions as the first heart. If it were biological, then it would weaken without use.
But a small pump to survive a heart attack would be nice.
- NAD.
  Having said that, if your "primary" heart is having issues it's usually something that a second heart wouldn't be able to bypass.
  For example, if the heart chambers are just fluttering then your second heart could try to take over, but I imagine that if the primary failing one would cause so much ruckus that the secondary wouldn't be able to keep up normal blood flow.
  I imagine a better system with some electronics that can either work as a pacemaker or take over completely in an emergency situation by just plain stopping the heart and taking over until help arrives, or something like that.
  Again, NAD

Worse if you're not a Time Lord or an octopus (or other multi hearted animal). They'd probably beat out of sync and cause turbulence in blood flow, which is quite bad.

The proverbial "two hearts in one chest" indicate a split mind, and create much pain.
It won't do no good. The two would work against each other.
Not only in the holistic meaning, also from a strictly materialistical / technical point of view, there is no way to make them work synchronized. It is the very nature of the heart to determine it's own rhythm.
- And even a singular heart can have some weirdness when it's own timing signals find alternate paths, like in some arrythmias.
  I can only imagine the chaos of trying to keep signals synchronized between two hearts.

Without your body evolving to require it? It would be worse.

31 comments