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Deepthought
07-05-2017, 02:09 AM
I'm looking into synthetic heart transplants, and I'm wondering about how the body would respond to emotional changes. For example, I know increased adrenaline will increase respiratory rate, shaking, etc. but will not trigger an increase in heartrate as it would in a natural heart. Some hearts are motorized so there wouldn't even be a heartbeat. What would someone with an artificial heart 'feel' in their heart if, for example, they heard something tragic or exciting?

Roxxsmom
07-05-2017, 03:01 AM
Oooh, that's a good question. Obviously, they wouldn't feel it pounding or racing, and artificial hearts can't currently respond to epinephrine. I imagine that even people with pacemakers wouldn't have the same cardiac response to stressful news or alarm, since their heart rate is artificially set/stimulated by the implanted device, and that would override physiological stimulation.

I am guessing that many of the sensations associated with stress, however, aren't really derived from the heart. That sinking feeling in the chest, for instance, but I don't know for sure.

I've never known anyone who had an artificial heart at any point. Currently, they're temporary devices, used to keep someone alive until a suitable transplant can be found. I believe the longest time someone has had one is four years. There are also size issues, since they are larger than actual hearts, so only larger adults can accommodate them readily. Though I just checked and there's a new, smaller model available now that was used successfully on a rather petite woman who needed one prior to a transplant.

http://newsroom.ucla.edu/releases/ucla-patient-is-first-to-successfully-receive-a-heart-transplant-after-using-experimental-50cc-total-artificial-heart

Nothing about what the things feel like, though. Here's one account, though it's anecdotal.

http://www.seattletimes.com/seattle-news/health/cold-reality-of-an-artificial-heart/

MDSchafer
07-05-2017, 03:01 AM
Artificial hearts aren't a thing... yet. Like we're just now using them in short term situations. The Total Artificial Heart only replaces the ventricles, not the entire heart.

So, yeah, you can do whatever you want here

Rachel
07-06-2017, 05:38 AM
I'm looking into synthetic heart transplants, and I'm wondering about how the body would respond to emotional changes. For example, I know increased adrenaline will increase respiratory rate, shaking, etc. but will not trigger an increase in heartrate as it would in a natural heart. Some hearts are motorized so there wouldn't even be a heartbeat. What would someone with an artificial heart 'feel' in their heart if, for example, they heard something tragic or exciting?

Crap, really? That's not very helpful. :(

I think you have to consider what the heart does, which is simply pump blood throughout the body. Adrenaline increases a natural heart rate so that you get faster blood flow > more oxygen delivery > more efficient use of energy > better ability to run or fight. Emotional cues don't directly affect the heart, regardless of the poets' opinions, but instead mimic other stresses that may increase chemical signals similar to adrenaline. Even if it simply makes you clench your hand into a fist, that stressor is technically requiring more energy of you, which you may not be able to supply.

As I mull over this, I'm thinking the first difference you'd notice is that you tire more quickly in response to any kind of stimulus (physical OR mental/emotional).

Deepthought
07-07-2017, 03:09 PM
I read a while back (not much in way of sample size, so take however many grains of salt you like) that a heart transplant had the effect of changing the personality of the patient closer to the donors. There is also the notion of the heart being able to think for itself. The heart has many neurons, is formed and functions before the brain is developed in a fetus, and even responds before the brain at times. I also discovered neurocardiology a little while ago. I just don't want to make the character act a certain way based on possibly false conclusions. I think I could write ambiguously and where the character himself is uncertain of his feelings and motivations.

Chris P
07-07-2017, 04:04 PM
I suspect there would be oxygen saturation sensors (or whatever they're called) that would cause the heart to circulate blood faster when the oxygen level drops or the body needs more, such as during exercise or excitement. Otherwise, the person would faint any time they exerted themselves beyond a certain level. I would totally believe that if I read it in a novel, even if it's not a real thing now.

Regarding your comment about a real heart transplant recipient's personality changing to resemble the donor, okay, I'm open to that idea but the scientist in me would look to the psychological effect of a major event (such as a heart transplant and the accompanying medical and emotional issues leading up to it) rather than the presence of a "thinking" organ. Comparing that to the person's loss of their own thinking organ and its replacement by a machine . . . hmmm. I think in some stories it would make a fascinating and deeply moving situation, and in others I think it would seem out of place.

As with anything in writing, it depends on what you want to say with the story and if this is the best way to show it.

Deepthought
07-07-2017, 06:00 PM
I'd want the character to be able to feel emotions normally. I think to myself how I'd feel hearing something that would make me feel strongly about something without my heart changing in response to what I heard. The heart and emotion are often linked, and there is no definite answer about it yet.