Implantation of the LVAD is "major surgery," according to Aaronson, and patients are hospitalized, on average, for three to four weeks.
The pump is placed in the abdomen. It is connected to a controller outside the body, a small unit (6 inches long, 3 inches high) that's generally worn on one's belt.
The LVAD can be powered by external batteries, or, while they recharge, a power pack with a 20-foot cord that allows mobility, said Aaronson.
The main risks are blood clots, which can cause disabling strokes in about 12 percent of cases. Other problems reported are hemolysis, or damage to red blood cells from the force of pumping; and infection or bleeding.
LVADs are used in patients with end-stage heart failure -- heart failure does not improve with other medical therapy. It's typically called New York Heart Association Class IV Heart Failure.
These are patients "with very limited life spans -- the threshold is different at different centers. In general, though, these devices are used as destination therapy in patients who have a 50 percent or higher risk of dying in the next six months. Quite frequently, these patients are likely to die in the next days to weeks if the pump is not implanted," Aaronson said.
But for some, the device buys more time than they could have expected.
"We have a patient now who is over 5 years," said Aaronson. "That patient had to have the device replaced after 4 years."
ABC News Medical Unit researcher Jane E. Allen contributed to this report.