From what I read in the past the lining of the lumens is in some flavour of frictionless material. They also generate faster and continous flows (there is no actual pulsing).

The physical layout will likely be designed to avoid turbulent flow.

Also I am not certain but they will probably put the patients on blood thinners to have some margin.

There's a different doctor that is using turbines to continually move blood. They have special bearings that prevent shredding and clots. Interesting note: a patient with this system will have no detectable pulse!

https://www.popsci.com/science/article/2012-02/no-pulse-how-...

Also, it seems that this doctor was pushing the turbine heart system on patients that didn't actually need it in order to further research.

https://www.houstonchronicle.com/news/investigations/article...

That was my first thought too. Clotting and mechanical shredding of red blood cells. These can be problems even over the span of a single operation where bypass is used.