[mamelukesabre]

Do these artificial hearts have any sort of ability to vary the flow rates in response to physical exertion?

[MonroeDNA]

The more advanced ones do, but the trouble is, they all break. All of them.

It's nice to be able to vary the flow rate for different things (sleeping, walking, running), but first we must have one that doesn't break. The electronics is way ahead of the mechanics. Blood clots, and components wear out.

Also, too much flow closes the Aortic valve. Not good.

Thanks for asking.

[MonroeDNA]

In a nutshell, you can't have any bearings inside, which either traumatize blood cells, or clot, and lead to failure.

All of the most advanced ones (Jarvik, Medtronic) know this, and are trying to overcome it. Problem is, if you reduce the flow for really sick folks, they tend to clot faster. Can't have blood cells lingering long enough to attack.