A man has survived a motorcycle accident in Italy which caused his heart to turn around inside his body and enter the right side of his chest.

Doctors at the emergency department who treated the 48-year-old man discovered that his heart was in the wrong place when they tried to check his heart sounds and rhythms. An X-ray and CT scan showed that his heart had turned 90 degrees to the right.

The new report on the case in the New England Journal of Medicine revealed the anatomical finding.

"This is a very interesting anatomical finding, and it's very unusual," Dr Gregory Fontana, of Lenox Hill Hospital in New York City, who wasn't involved in the case, told Live Science.

"I had never seen anything like it. What's unique about this case is the way the heart rotated so far in the other direction, and the patient was still awake and alert."

Initially, it was thought the man's heart rotated in the violent twisting motion of his body. Yet Fontana said the heart turned around after the accident.

The report revealed that injuries to the man's lungs at the time of the accident caused air to leak from the lungs and build up in the space in the chest. The build up of air pressure pushed the heart, causing it to turn to the right.

Around 24 hours after doctors had removed the air, the heart had returned back to its original position.

"The structures in the back of the heart, and the big arteries, are fixed to the spine and to the tissue, but the heart kind of floats around in the sac around it," Fontana said. "It's possible that some looseness in the sac or an injury to the sac around the heart allowed the mobile part of the heart to rotate on the fixed parts and end up on the wrong side of the chest."

The man suffered punctured lungs, broken ribs and a ruptured spleen. The rotation of the heart also obstructed blood vessels, which caused a drop in his blood pressure.