The LVAD is implanted next to the heart to help its main pumping chamber, the left ventricle, pump blood through the body. Such devices are used mainly for short periods, to buy potential transplant candidates time as they await a donor organ.

Cardiologists said that in Cheney’s case, the pump is likely a “bridge” that will keep him alive until he can receive a heart transplant. Many cardiac experts said at the time of his surgery that Cheney may be only one step away from a transplant but could find himself on a wait list for “months or years.”

“The HeartMate II is used in situations where the patient’s native heart continues to pump, but not normally and effectively,” said Dr. Timothy J. Gardner, a heart surgeon at Christiana Care Health System in Wilmington, Delaware, and past president of the American Heart Association.