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Comment by low_tech_punk | Hacker News Reader

It's cool and spooky that the patient will no longer have heart beat, because the rotor will deliver continuous blood flow.

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I've read a number of reports about that. Apparently it's a little unnerving at first, but the biggest problem is that they have to make sure that any medical professionals or people they know are aware that they don't have a heartbeat and that's expected and does not mean they need CPR.

Also, there's a long-term question of whether there are any processes within the body are keyed off of the heartbeat, because biological designs are often spaghetti and take full advantage of any random interaction and make it load-bearing.

The workings of our bodies are just the xkcd "holding spacebar makes the computer overheat" on a giant scale.

The regulation of any individual process in the body is a rube goldbergian nightmare of hormones and neurotransmitters and things that just happen to fire under the right conditions.

I have absolutely no doubt that something in the body relies on a periodic heartbeat in some fashion, but it seems so far to not be anything particularly critical.

Probably passive lymph pumping in organs that aren't muscular

CSF fluid too maybe.

Agreed. Hell, it wouldn't surprise me if some part of human neurology used heartbeat as a clock signal (particularly aspects that would benefit from speeding up in same situations the heart does).

>The regulation of any individual process in the body is a rube goldbergian nightmare of hormones and neurotransmitters and things that just happen to fire under the right conditions.

Yeah, it makes me wonder if would be possible to re-engineer some of this stuff to reduce the needless complexity and improve performance and reliability and service life. The problem is that there's so much spaghetti code that any change you make could have unintended consequences.

Ah, so like my codebase

I have a heart abnormality that shows up as an inverted T-wave on an echo cardiogram. Some physicians will immediately think I'm having some sort of heart attack, though I display no symptoms. It's actually that my heart fills fully and empties fully in a single cycle. I'm not a medical professional, so all I have are laymans explanations, but what it means is that my heart beats less frequently but stronger than the average heart. It was documented thoroughly throughout my time in the Marines and a cardiologist suggested it wasn't a defect. My heart rate remains much lower than other peoples when under stress and my heart rate at rest is only slightly lower than an average persons. When I asked him what all that meant he suggested that I probably won't die of anything heart related, but my body is otherwise normal.

If you don't mind me asking, what is your blood pressure with this abnormality? My gut feeling would be that it you have a much larger gap between your systolic and diastolic numbers than average?

It's actually less of a difference, I think. Systolic hovers around 110-115 and diastolic is anywhere from 80-90.

It almost sounds like an advantage? like, a positive mutation? does it allow you to push further while exercising?

If that's the case, I suggest having as many kids as partner will allow.

I was thinking that. Sounds like the OP has evolved.

So you're basically running a 2-stroke heart?

I would guess that, all things remaining the same, you'll have a life a lot longer than most people. I wonder if that behaviour could be induced in a normal heart, as it looks like it's a timing thing.

My guess was the opposite, that it would lead to scarring and eventual heart failure. Many top athletes end up with scarring on their heart from chronically working it so hard. My completely uneducated guess would be that the single power pulse would be a constant source of high impulse strain on the heart muscle, compared to two lower power pulses.

Get that tattooed on the chest.

My first thought also

That’s a tattoo that’d actually make sense.

And a deep meaning and usefulness

"Caution - rotating heart inside"

Make it with e-ink and attach a subcutaneous flexible PCB right below the pigmented layer so that the heart can communicate status in a visible way.

> Also, there's a long-term question of whether there are any processes within the body are keyed off of the heartbeat, because biological designs are often spaghetti and take full advantage of any random interaction and make it load-bearing.

I've heard it suggested that musicians keep time according to their heartbeat; I don't feel like I'm doing that when I'm playing music, but I'd be interested to see what a musician feels like after having this procedure.

I mean, with that level of heart failure that an artificial heart is required, there are a bunch of other medical concerns that should be reliably transmitted. As an example, people with diabetes might have tattoos.

Also, CPR is administered primarily when breathing is not sensed. If the patient is already in the hospital, they will surely check basic stuff, like a huge scar on the chest.

Though it would be very interesting if the machine would artificially output a potential vector that makes it very apparent to EKG and similar devices that it is operating, but it is not an ordinary heart (e.g. doing a square wave). It would require minuscule energy.

> Such a pump has no valves, so a patient using the Bivacor heart in its most basic mode would have no pulse. But we recently adapted our device to give it a pulsatile outflow option.

> The pump can run at constant speed, producing continuous blood flow at a constant pressure, and in our early experiments we concentrated on testing this “pulseless” mode. But it’s easy to change its speed, and our later experiments proved that controlled speed changes could produce a wide range of flow and pressure characteristics. Running the pump first at high speed (sending out more blood) and then at low speed (sending out less) creates something resembling a biological heart’s pulse; rapidly alternating these two speeds creates something that looks like a normal heartbeat.

> We’re now working primarily in that pulsatile mode. Within cardiology, there’s an open debate about whether a pulse is necessary for good health… [0]

The ieee.org article has significantly more detail and is a fascinating read.

- [0] https://spectrum.ieee.org/this-maglev-heart-could-keep-cardi...

The lack of pulsatile flow is associated with formation of AV malformations in the colon which can cause GI bleeding which is a more than a little problem when you have a piece of hardware in your chest which requires you take anticoagulants.

I wouldn't be surprised if the lack of pressure fluctuations would cause harm in the long run (although this isn't meant for the long run).

Hearts have been beating for a very, very long time, and I'm sure other biological structures have taken advantage of that.

I wonder if they prescribe something like walking or jogging as a substitute "repetitive movement" to get things moving.

This is a whole thing. Look up "pump head". Also check out:

https://ventriflo.com/

As I've understood it, not having a pulse creates all kinds of problems, blood clots and whatnot. It's simply not good for the blood, nor the blood flow. The body isn't made for it.

Pulsatile flow doesn't have such issues, so a Swedish company called Real Heart is making a TAH that pulses like a heart.

So far they've done successful tests with sheep and tons of testing of various blood parameters which look way better than traditional continuous-flow TAHs. Clinical trials on humans should be coming up relatively soon.

I hope they make it, and can improve it and make it smaller to fit children etc. It's pretty interesting technology.

Here is one from Carmat that is already in use in Europe

https://www.carmatsa.com/en/our_product/

Here's a video where Bivacor is working on making their impeller design simulate a pulse: https://youtu.be/3uV8XZcIBbk?si=I9Gf6pEd9v71Q7JJ. Also has nice interview with the inventor/founder Daniel Timms where he talks about the motivation for doing this companany i.e. when his dad got heart failure.

I’m sure it does cause some problems as the human body is very intricate, but in the capillaries blood flow is often approximated as a steady flow in medical science.

Even more spooky that if they died from, for example, a gunshot wound then their heart would continue to beat. apparently this is a serious issue for coroners when declaring death.m

Soon after the procedure a donor organ became available, so they no longer have the artificial heart.

Might it also have psychological effects?

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