An artificial heart, also known as a cardiac implant, was a device able to completely replace a heart in case of a major injury. Artificial hearts were more susceptible to weapon blasts, such as those caused by a compressed teryon beam, than the Human heart.
The procedure of replacing a parthenogenetic cardiac implant was performed conforming to Van Doren's technique and had a mortality rate of 2.4%; any well-equipped medical facility could perform this procedure. Placing a cardiac implant was performed by a medical team of six:
Prior to the operation, a neural caliper was used to anesthetize the patient, after which the operation began. The cardiac implant was placed via a mid-line entry. When the operation was finished, the patient had to stay in post-op for at least four hours. (TNG: "Samaritan Snare")
In 2365, Picard needed to have it replaced for maintenance reasons, so he traveled to Starbase 515, not wanting the crew to know by having the operation performed aboard the USS Enterprise-D, despite the fact that Doctor Pulaski was more than capable of performing the surgery. After a complication, she was required to perform the surgery anyway. (TNG: "Samaritan Snare")