The Texas Medical Center is moving ahead on its Bivacor rotary pump artificial heart.[0] It does not appear that Bivacor is a bridge to a transplant, but rather an end point. They kept a cow alive for many months a few years ago. Since it is a continuous rotary pump, the patient will have no pulse with this device.
One of the inventors behind Bivacor is Dr. Billy Cohn, an elite heart surgeon with a strong bent toward innovation. He would have an idea, hit his garage to cut up some plastic mesh, seal it, sterilize it, and be trying it in a patient in a few days. He jokes about Home Depot being his best source of medical equipment. In fact, he tells a hilarious Home Depot story in the middle of his standard talk on medical innovation.[1]
The Bivacor pump does have a pulse-like output, so I suspect some of the issues with earlier rotary pumps might not be so prevalent. Because it's a rotary pump though I suspect there's still issues with cell damage as they pass parts of the rotating assembly. The video claims that wide clearances reduce the risks of clotting from cell damage, but it's a reduction - not outright removal. See around the 3:40 to 4 minute mark on the video at https://www.bivacor.com/
The Carmat artificial heart was also developed as an end point, but it was easier for them to get it approved as a bridge to a transplant. One person had it at least for more than 2 years (it was in 2020 current fate is unknown).
This is not entirely correct. The default mode is pulse-less, but the bivacor can be spun up and down to simulate pulses (based on some articles I found looking at this a while back). I'm most curious about the auto rate adjustment. I'm assuming a built in oximeter? Also future revisions plan on a charge through skin internal battery. That'll be a killer (for lack of a better word) feature.
https://www.bivacor.com/ has a good explanation and video description of the system. It sounds really promising. The things I was most curious about are, it gets a charge from a battery you carry around on your person like a purse, and, it has a ten hour recharge time and comes with two batteries. I think I'd get a few more spares.
I would worry about something like the battery becoming disconnected when I sleep. Hopefully it has a very insistent alarm to alert the user. I'd also worry about getting mugged and having the mugger demand the battery from me.
One idea that seems cool is if you could manually control your blood flow rate. They say it does change but don't clarify if it's manual change or automatic. If it were manual, it would unlock some abilities. You could calm yourself by dialing down your heart rate or "warm up" by dialing it up.
Interesting to see that it uses bovine derived valves. Does anyone know the reason for that? Are real tissues less likely to cause issues with blood coagulation or have materials coatings caught up enough to solve that problem?
Does anyone know where modern thinking on the role of the heart is headed? I was intrigued to run across this article discussing the heart's role as more of a hydraulic ram and less of a pump:
Metal valves are only used in the young (i.e. under 50) because they are the most durable and can last a lifetime. The caveat is that lifelong blood thinners are needed because the metal provides a surface for clots to form. Bovine valves are the typical favorite because the body does not form clots on a bovine valve. They're usually sterilized and all cells killed so that it doesn't trigger tissue rejection. In the end, it's just a connective tissue matrix. Unfortunately, this means it is less durable and cannot heal from damage so they only last 10-15 years.
You’d need to ask a cardiologist of course, but I think for all intents and purposes, the science is in fact settled. The heart pumps blood.
In any field you see people using weak evidence to question strongly evidenced positions like in the linked article. I worked as a physicist for 7 years or so, and you frequently saw people using small deviations in experimental results to try and question general relativity, or parts of the standard model. Of course, when you see the few outliers lined up it seems convincing, but if you work professionally in the field you realize that that’s what they are - outliers. Just a handful of strange results in a literal flood of results that fit within and support the status quo.
And, fortunately or unfortunately, if you’ve seen it happen to someone, I think the evidence that the heart pumps blood is extremely convincing, having witnessed it first hand - if your heart stops, blood stops flowing. And we know that that is the correct order of causation, because to fix it, you shock the heart into pumping again.
You’d need FAR stronger evidence than failed drug trials (the vast majority of drug trials fail) or failed device trials (the vast majority of device trials fail) to seriously weaken that position, as far as I’m aware.
You use bovine or porcine generally. They last about 10 years. Metal valves last 30 years but require anti coagulation. Since porcine and bovine valves are zero from à immunogenicity standpoint, they’re ideal unless we could get human ones that are plugged into the circulatory system.
Although with a pump heart you’re going to be on blood thinners anyway. And probably a few other things.
The dream of where the heart is headed is to growing new ones. The best heart is a human heart suited to you
mechanical heart valves require patients to be on blood thinners for the rest of their life, bovine and porcine heart valves are most similar to human heart valves in size and shape and they have very good reliability without requiring the patient to continue taking blood thinners.
The vast majority of replacement valves implanted today also use animal tissue (bovine and pig). They are much more similar to the original valves than metal replacements.
As a layman creating a reliable pump that runs on a battery seems like it would be a fairly easy job for with modern technology. Of course anything mechanical is going to require regular maintenance, but again I wouldn't expect this to be a difficult problem.
What are the complications here? Size? Preventing infection? Does it need to adjust flow rate based on oxygen requirements?
The challenge isn't in building a reliable pump. The challenge is in the connection between the pump and the human body. If we just put a highly polished titanium tube in the circulation there will be blood clots, hemolysis, and other blood damage. Over time these problems become the main hurdle in getting these types of devices to work.
Does anyone have information about the 'external power supply' of the heart in the linked article? I've found some info that is years out of date and I'm wondering how unobtrusive the unit is now.
Yes, typically they include circuitry/ICs for brushless motor controller to spin the thing, plus a few more "motor" controllers if they have active magnetics for bearings, or other reasons. This needs to all be redundant, or otherwise safe in the mission critical sense. Then they have batteries, and all the stuff that goes with connecting the two (power regulation, conditioning, etc) and alarms, etc.
> The Duke patient ... was referred to Duke in June after a sudden, unexpected diagnosis of heart failure. Moore and his wife, Rachel, recently adopted their two-year-old foster son, Marshall, and arrived at Duke expecting only to undergo heart bypass surgery.
39-year-old admitted to the hospital with unexpected heart failure? Is there more to this story? Is this possibly related to the myocarditis being reported with some mRNA reactions?
The story I was told was that president Lyndon Johnson was having heart trouble. Coming right out of the Apollo age, the powers that be said "we can send a person to the moon, why can't we build an artificial heart". They thought it would be a relatively simple problem to solve. At that time the battery technology wasn't there, so the only way to make something work was nuclear power. They came up with an implanted sterling engine, powered by a nuclear thermopile with the cold side of the heat flow being the human body. In that case, the limiting factor for how much power could be generated was how much heat could we dump into the human body without causing things like internal burns and necrosis. They actually built several prototypes, tested them in animals, but never in humans. These devices were enormous, they typically had a large thermopile/sterling engine portion connected by a shaft or hydraulic connection to the pumping portion of the device. Both needed to be implanted in the body, and the devices were entirely mechanical, no electronics needed. The thermopile drove the sterling cycle engine, which then either acted on hydraulic working fluid to actuate the blood pump, or used a shaft or similar to actuate the blood pump from the sterling engine.
I have a feeling there isn’t enough power in nuclear at the scale that would fit inside the body with sufficient shielding. Nuclear is surely for low power devices, but human hearts would actually use a great deal of power (estimate 50-100W). It won’t last for years like you’d expect.
Even if you _can_ package it, still needs batteries for redundancy and clearly those don’t fit inside either. Patients with batteries carry around massive backpacks.
Brings a new meaning to ‘having a meltdown’ though. Overheating nuclear heart would literally boil your blood.
I just want something like this for my next kidney transplant, I'm so sick of the meds, yes I'm blessed to be alive and living a really good life, but man the 2nd kidney is starting to give me anxiety. Context: Transplant isn't a cure to my autoimmune disease, it will slowly pick away at the graft and have me needing another. Love reading about this kind of stuff.
Lots. The old gen, the only approved one, is actually the continuation of the Jarvik 7 made famous by the Barney Clark case. They've been making and using it all this time. It's now called Syncardia. It's pneumatic and the patients have to carry around a bit pneumatic driver that makes quite a bit of noise during every heartbeat. Patients have large air lines running in and out of their chest to carry the air in and out to drive the diaphragm based pump. It works, bit is not ideal in many ways.
I really feel for those that receive these implants and live with it for a few days more. The first such implant receiver lived for 3 months only. The next one maybe 1.5 years.
Personally I would have preferred to die rather than put a battery and pump inside my body as a heart.
Implanting an artificial heart is, like most surgical operations, a risky endeavor, especially for the first persons who are taking the most risks (and also helping the most to develop our knowledge).
The people choosing to have a new heart implanted do so with full knowledge of the risks, and potential reward (more time alive, helping to develop a new life saving technology/procedure, etc...).
If I get a serious disease that requires me to have a dangerous operation, I would love to have the choice to do so, instead of having to endure the disease with no choice.
I understand 'feeling' for people that have cardiac issues, but I cannot understand 'feeling' specifically for people that have cardiac issues and choose to undergo a risky and potentially saving surgery.
There are people with Heartmate II's (LVADS not artificial hearts, so a bit different) that have lived 10+ years on the devices, with a very high quality of life. That's worth it in my view.
[+] [-] tacon|4 years ago|reply
One of the inventors behind Bivacor is Dr. Billy Cohn, an elite heart surgeon with a strong bent toward innovation. He would have an idea, hit his garage to cut up some plastic mesh, seal it, sterilize it, and be trying it in a patient in a few days. He jokes about Home Depot being his best source of medical equipment. In fact, he tells a hilarious Home Depot story in the middle of his standard talk on medical innovation.[1]
[0] https://www.bizjournals.com/houston/news/2021/05/19/bivacor-...
[1] https://youtu.be/iHTVTU8PPGk?t=623
[+] [-] tech2|4 years ago|reply
[+] [-] lugged|4 years ago|reply
[+] [-] mahkeiro|4 years ago|reply
[+] [-] superbaconman|4 years ago|reply
[+] [-] ALittleLight|4 years ago|reply
I would worry about something like the battery becoming disconnected when I sleep. Hopefully it has a very insistent alarm to alert the user. I'd also worry about getting mugged and having the mugger demand the battery from me.
One idea that seems cool is if you could manually control your blood flow rate. They say it does change but don't clarify if it's manual change or automatic. If it were manual, it would unlock some abilities. You could calm yourself by dialing down your heart rate or "warm up" by dialing it up.
I hope this technology works!
[+] [-] EMM_386|4 years ago|reply
The former US Vice President Dick Cheney had a device (Heartmate II) that also resulted in him not having a pulse.
I'll refrain from any political jokes on HN.
[+] [-] 01100011|4 years ago|reply
Does anyone know where modern thinking on the role of the heart is headed? I was intrigued to run across this article discussing the heart's role as more of a hydraulic ram and less of a pump:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5215277/
I don't suppose the science is settled, but it is interesting that in the modern age we're still debating the function of such an important organ.
[+] [-] profile53|4 years ago|reply
[+] [-] atty|4 years ago|reply
In any field you see people using weak evidence to question strongly evidenced positions like in the linked article. I worked as a physicist for 7 years or so, and you frequently saw people using small deviations in experimental results to try and question general relativity, or parts of the standard model. Of course, when you see the few outliers lined up it seems convincing, but if you work professionally in the field you realize that that’s what they are - outliers. Just a handful of strange results in a literal flood of results that fit within and support the status quo.
And, fortunately or unfortunately, if you’ve seen it happen to someone, I think the evidence that the heart pumps blood is extremely convincing, having witnessed it first hand - if your heart stops, blood stops flowing. And we know that that is the correct order of causation, because to fix it, you shock the heart into pumping again.
You’d need FAR stronger evidence than failed drug trials (the vast majority of drug trials fail) or failed device trials (the vast majority of device trials fail) to seriously weaken that position, as far as I’m aware.
[+] [-] robbiep|4 years ago|reply
The dream of where the heart is headed is to growing new ones. The best heart is a human heart suited to you
[+] [-] c-slice|4 years ago|reply
[+] [-] superjan|4 years ago|reply
[+] [-] unknown|4 years ago|reply
[deleted]
[+] [-] kypro|4 years ago|reply
What are the complications here? Size? Preventing infection? Does it need to adjust flow rate based on oxygen requirements?
[+] [-] jstanley|4 years ago|reply
[+] [-] iancmceachern|4 years ago|reply
[+] [-] readams|4 years ago|reply
[+] [-] albertTJames|4 years ago|reply
[+] [-] korse|4 years ago|reply
[+] [-] iancmceachern|4 years ago|reply
[+] [-] ed25519FUUU|4 years ago|reply
39-year-old admitted to the hospital with unexpected heart failure? Is there more to this story? Is this possibly related to the myocarditis being reported with some mRNA reactions?
[+] [-] iancmceachern|4 years ago|reply
[+] [-] villgax|4 years ago|reply
[+] [-] iancmceachern|4 years ago|reply
The story I was told was that president Lyndon Johnson was having heart trouble. Coming right out of the Apollo age, the powers that be said "we can send a person to the moon, why can't we build an artificial heart". They thought it would be a relatively simple problem to solve. At that time the battery technology wasn't there, so the only way to make something work was nuclear power. They came up with an implanted sterling engine, powered by a nuclear thermopile with the cold side of the heat flow being the human body. In that case, the limiting factor for how much power could be generated was how much heat could we dump into the human body without causing things like internal burns and necrosis. They actually built several prototypes, tested them in animals, but never in humans. These devices were enormous, they typically had a large thermopile/sterling engine portion connected by a shaft or hydraulic connection to the pumping portion of the device. Both needed to be implanted in the body, and the devices were entirely mechanical, no electronics needed. The thermopile drove the sterling cycle engine, which then either acted on hydraulic working fluid to actuate the blood pump, or used a shaft or similar to actuate the blood pump from the sterling engine.
a few links: https://physicstoday.scitation.org/doi/full/10.1063/PT.3.316... https://ota.fas.org/reports/8232.pdf https://www.nytimes.com/1972/03/21/archives/nuclear-heart-pu... https://www.theatlantic.com/technology/archive/2013/03/the-t...
[+] [-] aetherspawn|4 years ago|reply
Even if you _can_ package it, still needs batteries for redundancy and clearly those don’t fit inside either. Patients with batteries carry around massive backpacks.
Brings a new meaning to ‘having a meltdown’ though. Overheating nuclear heart would literally boil your blood.
[+] [-] alod|4 years ago|reply
Unfortunately we moved away from the Jetson's future.
[+] [-] bserge|4 years ago|reply
[+] [-] 12bits|4 years ago|reply
[+] [-] throwitaway1235|4 years ago|reply
(Albeit non-human)
[+] [-] The_rationalist|4 years ago|reply
[+] [-] iancmceachern|4 years ago|reply
[+] [-] parsecs|4 years ago|reply
[+] [-] habibur|4 years ago|reply
Personally I would have preferred to die rather than put a battery and pump inside my body as a heart.
[+] [-] wetpaws|4 years ago|reply
You do, someone else would not. I don't see any issues with this, it's not a zero sum game.
[+] [-] bserge|4 years ago|reply
Sadly, all of that would likely be painful, so it's just a daydream.
[+] [-] Majestic121|4 years ago|reply
Implanting an artificial heart is, like most surgical operations, a risky endeavor, especially for the first persons who are taking the most risks (and also helping the most to develop our knowledge).
The people choosing to have a new heart implanted do so with full knowledge of the risks, and potential reward (more time alive, helping to develop a new life saving technology/procedure, etc...).
If I get a serious disease that requires me to have a dangerous operation, I would love to have the choice to do so, instead of having to endure the disease with no choice.
I understand 'feeling' for people that have cardiac issues, but I cannot understand 'feeling' specifically for people that have cardiac issues and choose to undergo a risky and potentially saving surgery.
[+] [-] iancmceachern|4 years ago|reply