I work with cardiac patients. Often, we'll have to implant a pump that supports or takes over the function of a heart until a transplant is available. There used to be only two long-term devices available for this... a Thoratec, which uses a console the size of a fridge that shuttles air to pumps laying outside the body, continually attached, you have to use anticlotting drugs so the risk for internal bleeding is always a danger.
The second is the implantable Heartmate, a dinner-plate sized device that gets implanted in your abdomen, fed either air or electricity through a line exiting the right lower portion of your belly. More portable, and the textured titanium surfaces mean only an aspirin a day is needed to keep clots from forming. It's big though, can't be used in small people or kids.
Now there's this... The Heartmate II. Tiny, it gets away from the idea that blood flow has to be pulsatile, using a continually spinning impeller to maintain a constant blood flow, much like a jet boat's drive.

Here's the impeller...it spins at 6000-10000 rpm to provide a "normal" cardiac output.

Here it is in place.

I think the weirdest part with these new patients is that they'll neither have a pulse or a measurable blood pressure, since both of these are dependant on pulsatile flow. Interesting stuff.