D'Zhana Simmons, 14, suffered from dilated cardiomyopathy, a condition in which a patient's heart becomes weakened and enlarged, failing to pump blood efficiently.
She had heart transplant surgery in July, but the organ failed to thrive in its new body. Without a readily available second transplant heart, doctors kept the teen alive for weeks with an external artificial heart pump.
After hooking her up to the device, they removed the malfunctioning transplant heart, even though doctors typically maintain both the mechanical and human hearts in their transplant patients.
Doctors at Miami's Holtz Children's Hospital replaced the artificial heart device on October 29 after a compatible human heart was located for the girl.