In the worst cases, the only treatment is a transplant. But with more hearts failing than being donated, patients can spend years on a waiting list.To help people awaiting a transplant, French company Carmat has developed a “total artificial heart” — a device to replace the whole heart until a donor can be found. Similar in shape to a human heart and weighing 4 kilograms, it is powered by two battery packs that provide around four hours of charge before the device needs to be connected to a mains power supply. This 'snake robot' can fix pipelines on the ocean floorSensors detect blood pressure and in response, an algorithm controls the blood flow in real time. “It works like a human heart so if the patient walks, the blood flow increases and if the patient is at rest, the blood flow is stable and low,” Carmat CEO Stéphane Piat tells CNN Business.Read MoreThe parts in contact with the patient’s blood are made from material that’s compatible with the human body, to reduce the risk of adverse reactions. Once surgically implanted, the device requires no maintenance, says Piat. Ready for marketNineteen patients have so far received the device in trials and in December, the company received a CE marking, allowing Carmat to sell the product in the European Union. Last month, it received authorization to start a feasibility study to gain approval from the US Food and Drug Administration.Carmat hopes to start selling its artificial heart in Germany by the end of June. By the end of the year, Piat aims for Carmat to have made 20 hearts, which will be sold to hospitals for over €160,000 each ($190,000). While its suitable for most men, the current design is too big for most women.An app that measures pain could help people with dementiaCarmat was established in 2008 but French surgeon Alain Carpentier started developing its artificial heart 25 years ago. The company now has around 190 employees and has received more than €250 million ($300 million) in funding.Martin Cowie, a professor of cardiology at Imperial College London, says researchers have been trying for decades to create a mechanical pump that can completely replace a heart. He says past attempts frequently caused strokes, blood clots, and infections, but the materials used by Carmat are a step in the right direction. He adds that the design is an interesting concept. “Time will tell … but I like their ideas,” he tells CNN Business. Other devicesThe cardiovascular disease technology market will be worth more than $40 billion by 2030, according to market research company IDTechEx.Other total artificial hearts are in development, but the only one currently on the market is produced by Arizona-based SynCardia. It has a fixed beat rate, rather than autonomously adjusting to the patient’s physical activity. Another French company — CorWave — is developing a device for people with less severe heart failure. It helps pump blood from one of the heart’s four chambers, rather than replacing the whole heart.CorWave’s “left ventricular assist device.”CEO Louis de Lillers says CorWave has secured about €80 million ($96 million) in funding, including €15 million ($17.9 million) from the European Commission, and is preparing for clinical trials in the United States and Europe. A number of devices that help pump blood from one chamber already exist, but de Lillers says CorWave uses new technology that makes it more responsive to a patient’s activity.”We’re able to track the activity of the patient and are able to adapt the flow to the patient’s needs,” he says.A device for life Although Carmat and CorWave will initially market their devices as temporary measures for patients awaiting a transplant, the long-term goal for both companies is to make devices that can be used permanently.”The vision is (for it) to be used as … a device for life,” says Piat. “But that means collecting longer term data, so it takes more time.” Cowie is pleased to see companies trying new approaches, and believes many people could benefit.”I think we could get to the stage where we could honestly say to patients that you’re as likely to do well with a mechanical pump as you are with a transplantation,” he says.