New approaches to electromechanical artificial hearts involve the replacement of some portions of the machine with tissue, such as the cow heart tissue used in this case. The end result is a more durable apparatus that better interfaces with the body, though it's still the case that artificial heart technology cannot replace a biological heart for the long term:

A new kind of artificial heart that combines synthetic and biological materials as well as sensors and software to detect a patient's level of exertion and adjust output accordingly is to be tested in patients at four cardiac surgery centers in Europe and the Middle East. If the "bioprosthetic" device, made by the Paris-based Carmat, proves to be safe and effective, it could be given to patients waiting for a heart transplant.

In Carmat's design, two chambers are each divided by a membrane that holds hydraulic fluid on one side. A motorized pump moves hydraulic fluid in and out of the chambers, and that fluid causes the membrane to move; blood flows through the other side of each membrane. The blood-facing side of the membrane is made of tissue obtained from a sac that surrounds a cow's heart, to make the device more biocompatible. "The idea was to develop an artificial heart in which the moving parts that are in contact with blood are made of tissue that is [better suited] for the biological environment."

That could make patients less reliant on anti-coagulation medications. The Carmat device also uses valves made from cow heart tissue and has sensors to detect increased pressure within the device. That information is sent to an internal control system that can adjust the flow rate in response to increased demand, such as when a patient is exercising.

Link: http://www.technologyreview.com/news/515021/the-latest-artificial-heart-part-cow-part-machine/

Source:
http://www.fightaging.org/archives/2013/05/a-bioprosthetic-heart.php