1982

Artificial Heart

Robert Jarvik (b. 1946)

In healthy people, the heart beats without pause for an entire lifetime, pumping 5 million gallons (19 million liters) of blood or more during 70 or 80 years of operation. But when something goes wrong and a heart needs to be replaced, the scarcity of natural replacement hearts creates a big problem. Thus engineers set about trying to design and build artificial mechanical hearts. However, nature’s pump is very difficult to duplicate.

There were four problems that doctors and engineers had to solve to make an artificial heart work: 1) Finding materials with the right chemistry and properties so that they did not cause an immune reaction or internal clotting in the patient, 2) Finding a pumping mechanism that did not damage blood cells, 3) Finding a way to power the device, 4) Making the device small enough to fit inside the chest cavity.

The Jarvik-7 heart, designed by American scientist Robert Jarvik and his team in 1982, was the first device to meet these requirements reliably. It features two ventricles like a natural heart. Its materials avoided rejection and were smooth and seamless enough to prevent clotting. The pumping mechanism used a balloon-like diaphragm in each ventricle that, as they inflated, pushed blood through the one-way valve without damaging blood cells. The only compromise was the air compressor, which remained outside the body and transmitted air pulses to the heart with hoses running through the abdominal wall. The basic design was successful and has since been improved as the Syncardia heart, used in over 1,000 patients. One patient lived almost four years with the heart before receiving a transplant. The Abiocor heart uses a different approach that allows batteries and an inductive charging system to be implanted completely inside the body. It also has a diaphragm arrangement but fluid flow rather than air fills the diaphragms. The fluid flow comes from a small electric motor embedded inside the heart.

Two different engineering approaches: One goes for complete embedding. But if something goes wrong, it probably means death. In the other, much of the system is outside the body for easy access and repair, but tubes pass into the body from outside.

SEE ALSO Defibrillator (1899), Heart-Lung Machine (1926), Lithium Ion Battery (1991).

The CardioWest TAH-t, pictured, is the first and only FDA, Health Canada, and CE-approved temporary Total Artificial Heart in the world.