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?
Having two pumps working together in a system where their output has to be adequately pressurized (instead of just filling a non- pressurized vessel) doesn’t sound easy to actually make work.
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 can imagine any time desynchronization of their work would occur, there would be a risk of heart valve damage. No matter if their connection would be serial or parallel. But then again, I have no idea if I correctly imagine how hearts work. (speaking out of my ass)
Desychronization will likely happen considering the heart rate is varying. Both must somehow increase by exactly the same rate. Any slight variation will cause them to go out of sync.
Once they’re out of sync, it’s going to be hard for them to get back in sync.
This is assuming both hearts are independent systems. Could be a different story if there dependent (like connected in series rather than parallel), but in that case it’s conceptually no different than having one heart.
The heart is a really simple contraption. The heart is broken down into 2 halves, and 2 more halves after that, for a total of 4 parts.
Focusing on one half, what most people would recognize as “the heart” and what it does. Blood enters the heart into a mini pump, that pump pushes blood into a second pump, making it a little extra full, so when that pump decides to squeeze, you get extra force leaving it to send blood to the rest of the body and back to the other half of the heart later.
Imagine filling a water balloon with half way some water and squeezing it out. It doesnt have as much “umph” as if you filled that same water balloon nearly to its popping point and squeezing.
The other half of the heart is the exact same, just weaker as it only sends blood a short distance to your lungs and back to the big half of the heart. Thats it, thats all the heart does. 2 pumps that load up the other 2 pumps with blood to be shot out to the rest of the body.
Sometimes things go wrong, youve very likely felt a small heart spasm before, but the heart is a mostly self correcting, fully autonomous system. I cannot see why adding in a 2nd heart would be a detriment, just makes blood go round and round more often.
I spent a few years studying as an EMT and Medical Assistant and I think I loved the circulatory system the most. However, Im no doctor and I simplified the heart a bit because I dont think needing to understand everything adds to the theoretical discussion of 2 hearts
My concern would be complexity.
More points to fail, and I’m not sure that it reduces single-points of failure much.
I understand the concern, but I see it as more redundancy, like kidneys. If 1 heart gives out, you have a spare, and considering that we only have 1 that can do its job for 100+ years i dont see complexity as being an issue.
Also Im just here to advocate the theoretical that you could have 2 hearts with no issues, rather than it being something completely impossible.
The problem comes in, what happens when a heart fails? depending on the failure mode, it may represent a total blockage, in which case you’re toast. You might be able to survive with one heart if you had two, but if you add a second heart, then your other heart will likely be less developed unable to perform at whatever peak performance you had before.
If your method of redundancy adds more single points of failures. Also, the addition of a second heart poses the problem of keeping them coordinated; with all sorts of problems coming up if they get out of sync. adding redundancy will always add complexity, especially as you work to remove single points of failure and try not to add extra. In some systems, it’s just unwise to add redundency because the complexity means it’s more likely to fail.
Famously, Charles Lindbergh, for example, opted for a single reliable engine over two engines. It kinda flew in the face at the time. But then he was the first to go from NY to Paris in a non stop flight, in the Spirit of St Louis. Similarly, we can expect, if there was in fact some significant advantage, that then, everybody would be doing it. Or, at least, lots.
Keep in mind, cephalopods have 3 hearts- 2 are single chamgered things that boost blood over gills, and the 3rd provides bloodflow to the rest of the body. Hagfish have one chambered heart and several boster things that aren’t really much of a heart. Earthworms aren’t possessed of true hearts (they lack chambers and valves,) cochroaches and leaches also don’t have true hearts.
But where we see 4 chambered hearts (birds, mammals, and crocodillian reptiles,) they all only have 1. That should tell you something.
I agree with what youre saying completely, Im just saying i theoretically could see how you could live with 2 hearts, not the efficiencies, intricacies, or failures of having 2.