But such pumps are often used as a bridge for patients who need a heart transplant, medical correspondent Dr. Jennifer Ashton said Wednesday on CBS' "The Early Show".
The heart pump, known as a ventricular assist device, pushes blood continuously through the body in place of a normal heartbeat, creating the oddity of a patient with no pulse. Some patients live with the pumps for years; others use them only as a crutch while waiting for a full transplant.
"This device can be used as a bridge to transplant in some cases for patients who are so sick they will not survive until they receive a heart transplant," Ashton said. "In other cases it can be used as destination therapy where no transplant is planned and they expect to live the rest of their lives with this device."
Only Cheney and his doctors know which scenario best describes him, but Cheney appears drastically thinner - and it is likely a symptom of late-stage heart failure known as "cardiac wasting," Ashton said, and not simply the trimmer figure of someone who has tried to shed weight.
Cheney, 69, can still qualify for a heart transplant, but "all organ transplants go through a network and you have no priority based on celebrity status or wealth," Ashton said. "What you do have priority status is based on how sick you are. The sickest patients are at the top of the list."