For decades, the quest for the perfect artificial heart has been wrought with many technical challenges that have made it difficult to design a device that mimics the living, pumping organ.
But Drs. Billy Cohn and Bud Frazier of the Texas Heart Institute say that trying to copy the function of the living organ has been part of the problem. They’ve developed a non-beating, non-pumping machine that delivers blood through the body with the use of simple whirling rotors. Although such a device would leave a person without a pulse, it could work better than pumping devices, thereby prolonging the patient’s life while also reducing the chance of infection or other complications.
Inside the institute’s animal research laboratory resides an 8-month-old calf. The team has removed the calf’s heart and replaced it with two centrifugal pumps that ‘spin’ blood throughout the animal’s body.
“If you listened to her chest with a stethoscope, you wouldn’t hear a heartbeat,” Cohn told NPR station KUHF in Houston. “If you examined her arteries, there’s no pulse. If you hooked her up to an EKG, she’d be flat-lined.”
After practicing on 38 calves, in March the team tried their device on a human patient, 55-year-old Craig Lewis. Lewis was dying from amyloidosis, a disease that causes buildup of abnormal proteins that clog the organs until they stop functioning. When his heart became damaged, doctors gave Lewis 12 hours to live, so he opted to try the artificial heart.
Cohn and Frazier took two medical implants known as ventricular assist devices and joined them together. A ventricular assist device has a screw-like rotor of blades that propels the blood forward in a continuous flow.
Thousands of people, including former Vice President Dick Cheney, have one of these implanted near their hearts. But by using two, the doctors replaced both the right and left ventricles — essentially Lewis’ entire heart.
Although Craig Lewis died a month later, due to the underlying disease attacking his kidneys and liver, doctors not only said the pumps performed flawlessly, but that continuous-flow pumps should last longer than other artificial hearts and cause fewer problems because each side has just one moving part: the constantly whirling rotor.
“These pumps don’t wear out,” Frazier says. “We haven’t pumped one to failure to date.”
The doctors will have to decide on a final design before they can bring the pulse-less, continuous-flow artificial heart to the market. As well, they will need to find a manufacturer and get approval from the Food and DrugAdministration. But the promise of a better artificial heart could give the thousands of people on organ donor waiting lists a ray of hope.
Credit: Courtesy of the Texas Heart Institute