CHANGSHA - A pair of conjoined twin sisters, who shared the same heart and liver, died on Monday in Central China's Hunan province as medical attempts to save them failed.

The twins survived for only 11 days. They died because of their deformed heart, which could not guarantee a normal blood supply and meant they lacked oxygen, said Li Bixiang, a surgeon with the Hunan Provincial Children's Hospital.

It was impossible to operate on the twins as their deformed heart left them in serious illness, said Li.

The twins were born on August 30 in Yanling county with a weight of 4.5 kg and were transferred to the Hunan Provincial Children's Hospital the next day.

Conjoined twins are identical twins joined in utero. The occurrence is estimated to range from 1 in 50,000 births to 1 in 100,000 births, with a somewhat higher incidence in southwest Asia and Africa.

Most conjoined twins are stillborn and many of the pairs born alive have seriously debilitating abnormalities.