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Comment by typest | Hacker News Reader

The heart is fundamentally a pump. Are we not able to build a replacement? I understand it’s not simple at all, and that people have tried and failed in the past, but is an artificial heart something that we should be able to build?

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It might be a significantly hard problem: for instance, artificial heart valves tend to get infected by bacteria, and if it were the case for a whole artificial heart to get infected, perhaps it could spread and cause damage to the mediastinum (or), maybe, sepsis.

Significantly, the body does a poor job of fighting infection that occurs in artificial heart valves.

Why?

From what I have read, artificial heart valves, being artificial, are simply not really covered by the immune system. In other words, you get white blood cells to the point of infection because you have blood supply and mechanical parts don't have blood vessels running through them.

It's foreign matter, not really part of a living body.

Very likely, they probably also attract infections that like eating plastics and such. These are inherently hard for the human body to combat if they get traction, from what I gather. They aren't a normal infection in humans and tend to be deadly when they do take root.

IIRC, the problem with conventional mechanical pumps is that they're continuous-flow. Various other systems in the human body rely in the ebb-and-flow of a pumping heart to function correctly, and different activities require different flow speeds. Yes, we can probably engineer a variflow pump as well, and maybe also one that increases and decreases its flow based on hormonal signaling, but it's not as simple as taking your average aquarium pump and connecting it in-place. AFAIK, we have no idea how the heart determines its flow rate.

I was under the impression there were implantable impeller style pumps that people used to replace the heart while waiting for a transplant.

They don't replace, they assist. Longest one has lasted is seven years. https://en.wikipedia.org/wiki/Ventricular_assist_device

Artificial hearts already exist. But they usually are only used while waiting for transplants, because they're not as good as the real deal.

Hearts are critical infrastructure in the body, with 100% uptime requirements and not-insignificant energy consumption.

Carmat has been working on it for a few decades. I believe they have not been approved yet by the FDA but are in the clinical trials phase.

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

Artificial hearts have existed for years but require an external power source to operate the pump. They can generally only be used for a limited time while waiting for a transplant.

https://syncardia.com/clinicians/our-products/freedom-portab...

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