For years, medical researchers have developed one device after another to replace diseased or damaged parts of the human body. One of the biggest hurdles was the heart: There are some devices on the market today, but they are only approved for temporary use in patients who are awaiting heart transplants.

So it was a major breakthrough when, on Dec. 18, doctors in Paris implanted an artificial heart that is expected to last five years. The patient was soon conscious and talking to relatives. The manufacturer, Carmat, a French startup with about 40 employees, was rewarded with a thank-you letter from French President Francois Hollande and a 10 percent surge in its share price on Monday, the first full trading day after the operation was reported.

The Carmat heart is a two-pound device powered by a watchlike battery that can be worn outside the body. Because it is bigger and heavier than a human heart, it isn't suitable for smaller patients. It is, however, a replica of the heart in functional terms: Thanks to an array of sensors, it speeds up blood circulation during exertion and slows it down during sleep. It uses some animal tissue to make sure it isn't rejected by the body, but otherwise it's a man-made mechanical device operated by sensitive electronics.

The French government approved the first four implants of the Carmat device in September. Belgium, Poland, Slovenia and Saudi Arabia came through with their approvals even earlier.

SynCardia Systems Inc., a closely held company based in Tucson, Arizona, makes a device very similar to Carmat's. It too regulates blood flow according to activity. The major difference is that SynCardia's model isn't approved for permanent use, though it is awaiting Food and Drug Administration approval for "destination therapy."

Another pioneering prosthetic, the Argus II artificial eye, was unveiled earlier this year by Second Sight, a closely held company based in Sylmar, California. The device treats blindness in people suffering from retinitis pigmentosa, a genetic condition that damages retinal cells. The Argus II is implanted in the eye, and glasses fitted with a video camera transmit visual information to it via a wireless connection, bypassing the damaged cells. By the time Second Sight announced Argus II, it had the FDA's approval, but it still isn't marketed in the U.S. because of further regulatory hurdles. Because it contains a radio device, it needs the Federal Communication Commission's OK, too. The company hopes to secure it in January. Meanwhile, the Argus II is available in Europe.

Indeed, Europe often leads the U.S. in bringing replacement body parts to the market -- not because its researchers have much of an edge but because its health-care regulations are less cumbersome.

According to the United Network for Organ Sharing, there are 121,291 people in the U.S. on the waiting list for life-saving transplants. The U.S. Department of Health and Human Services says 18 people die each day due to a shortage of donated organs. While there are some ethical concerns with the man-made replacement parts -- such as the prospect of creating super-beings with organs that work better than the originals -- at this point the devices are urgently needed to save lives or dramatically improve the quality of life of suffering patients. Thousands of people could benefit from a single global system of approving vital technology for medical use, or even from a rule allowing the universal adoption of such technology after two or three countries issue approvals.

(Leonid Bershidsky, an editor and novelist, is a Bloomberg View contributor. Follow him on Twitter.)