A man from the United States got a heart transplant from a genetically-modified pig, in a world first.

According to the BBC News, David Bennett, 57, is continuing to do well three days after the surgery took place in Baltimore.

The transplant took place as it was considered the last hope of saving Mr Bennett's life, although it is unclear what his hopes of long-term survival might be.

He had initially been deemed ineligible for a human transplant, which is a decision usually taken if a patient has been in very poor health.

Redhill And Reigate Life: Surgeons spent seven hours on the procedure (PA)Surgeons spent seven hours on the procedure (PA)

As BBC News reported, Mr Bennett was happy to take the chance with this choice.

A day before the procedure he said: "It was either die or do this transplant. I know it's a shot in the dark, but it's my last choice."

The pig used in the transplant had been genetically modified to knock out several genes that would have led to the organ being rejected by Mr Bennett's body, the AFP news agency reports. 

For the medical team that carried out the transplant, it marks the culmination of years of research, as the use of animal organs in transplants like this has long been considered.