Biomedicine Update – Healing the Heart

The expression “in a heartbeat” may not have the same meaning in the future if technology under development has a say. Conventional thinking on replacing the heart with a device that works the same way as the heart is being turned on its head by devices that don’t beat at all. These new artificial hearts are turbines that push blood through the body, not in spurts but in a steady stream. Called continuous-flow devices they have been under development for the last two decades.

The model for continuous-flow is Archimedes’ screw, the 3rd century B.C. device designed to pump water from the Nile River to the fields that lined its banks. Archimedes’ screw is still in use in Egypt today and Richard Wampler, a surgeon and engineer, first encountered them in a trip to Egypt in 1976. A decade later he patented a device based on this ancient technology but instead of moving water his was designed to move blood.

In use since the 3rd century B.C., Archimedes

Initially the device was used to assist failing and post-surgical left ventricles (the primary pumping chamber for delivering blood through the ascending and descending aorta to the body). Before Wampler’s device left ventricle assist devices or LVADs required external compressors and pulsed like the heart. Wampler’s device didn’t. Many surgeons and cardiologists were skeptics. They were concerned that blood passing through a turbine would be damaged. But the continuous-flow turbines did no damage to blood cells when implanted in test animals.

In November 2003 a commercial version of the pump, called the HeartMate II was implanted in a young patient from Central America. He left the hospital and didn’t return. The young man’s heart prior to the surgery was weakened but still functioning. During the eight months he was away before coming back for a followup examination his heart pretty much stopped functioning. When examined he had no pulse and nothing that one would recognize as a heartbeat. But he was walking around and functioning and described himself as “feeling fine.”

The continuous-flow artificial heart consists of twin turbines designed to circulate blood throughout the body. Unlike prior artificial hearts, it doesn’t beat.

Since 2008 HeartMate II has been installed in 11,000 people worldwide. This device, an enhanced LVAD, has had a wonderful side effect in many patients. It reverses heart failure confounding cardiologists who assumed that any damage to the heart was permanent.

From LVAD to a continuous-flow artificial heart implanted in humans is a matter of less than a decade according to the developers of this technology and the medical teams that are implanting them. Currently these new devices are undergoing animal clinical trials with encouraging results. It is only a matter of time, not in a heartbeat, but certainly within a decade before artificial hearts will be commercially available for humans.

Len Rosen lives in Toronto, Ontario, Canada. He is a researcher and writer who has a fascination with science and technology. He is married with a daughter who works in radio, and a miniature red poodle who is his daily companion on walks of discovery. More...