Surgeons successfully inserted the heart of a genetically modified pig into a human patient in a first-of-its-kind operation, saving his life after he had previously been ruled ineligible for a regular heart transplant.

On Monday, David Bennett Sr, of Maryland, was in good health after the treatment, and his doctors at the University of Maryland Medical Center were keeping an eye on him.

Doctors say Bennett is doing well three days after the seven-hour experimental treatment in Baltimore.

Bennett’s life was thought to be on the verge of being saved by the transplant, albeit it is unclear how long he will live.

The US medical regulator granted a special dispensation to doctors at the University of Maryland Medical Center to carry out the procedure on the basis that Bennett – who has terminal cancer – had been deemed ineligible for a human transplant, a decision that is frequently made by doctors when the patient is in critical condition.

Three genes were removed from the donor pig to prevent human immune systems from rejecting pig organs, and one gene was removed to avoid excessive pig heart tissue growth. Six human genes involved in immunological acceptance were added.

The transplant is the culmination of years of research for the medical team who performed it, and it has the potential to impact lives all across the world.

Surgeon Bartley Griffith stated that the surgery was a step towards bringing the world “one step closer to solving the organ shortage crisis”. In the United States, 17 individuals die every day while waiting for a transplant, many of whom have heart disease and would have died otherwise.

Animal organs for so-called xenotransplantation have long been regarded as a way to meet demand, and pig heart valves are now widely used.

This historic moment raises the possibility of finding a solution to the ongoing scarcity of human organ donors. However, there is still much work to be done to evaluate whether or not giving people animal organs is the way to go.

Pig hearts are structurally comparable to human hearts, but they are not identical, as you might expect. However, they can be plugged in and made to work.

Organ rejection is the major problem. These pigs have been bred to be immune to rejection-causing genes.

They are cloned with specific genes “knocked out” and raised until their organs are large enough for donation.

It is too early to tell how Bennett’s pig heart will turn out. His doctors made it apparent that the procedure was a risky proposition. The stakes are high, but so are the rewards.