Every year between 2,000 and 3,000 people in the United States get a new heart from an organ donor. About the same number of people remain on waiting lists and many die before they ever get a chance at a transplant.
Artificial hearts are currently used as a stopgap measure while patients wait to get a donor heart. By definition the hearts only last a certain amount of time. That can be years — one made by SynCardia Systems, Inc. has lasted up to 1,374 days — but it’s still not a permanent solution. On top of that, an artificial heart requires a “driver” that has to be worn outside the body and connects through the skin — increasing the chance for infection.
Paris-based Carmat has built the first implantable artificial heart that exists completely inside the chest cavity, with no external components. Locating everything inside the body cavity reduces the number of sites where infection can happen and could allow the replacement heart to last longer than current models.
The device has two chambers, each divided by a membrane. On one side of the membrane is hydraulic fluid, while the other side faces the blood.
A pump moves the fluid in and out of the chambers. The fluid moves the membrane, and that in turn pushes the blood in and out of a chamber, just like a real heart. The “blood” side of the membrane is made of tissue from a cow’s heart. The valves in the device are also made of cow tissue.
Using the animal tissue could, the designers say, make the patient less prone to blood clots, which cause strokes, among other problems, and reduce the need for anti-clotting medications.
Carnat’s device also uses a system of sensors to transmit data about the patient to a computer, which signals back to the device to adjust it’s pumping rate to match a patient’s level of exertion. It’s powered by a battery that is self-contained and charge via induction.
It’s not clear yet how long this device can last. The human body is not an easy place for any mechanical device. It’s salty, which causes corrosion. And a heart has to beat a lot — at a resting heart rate of 60 beats per minute, that adds up to 86,400 bets per day, or 31.5 million per year. Designing anything that can last that long with that much wear is a tough challenge. The device will be tested on patients in Europe and the Middle East.