HERKENBOSCH -- Four decades after being diagnosed with a serious heart condition and given just six months to live, Bert Janssen has set a Guinness World Record as the longest-surviving transplant patient.

"I want to be an example for people," said the Dutchman, who was 17 when he was diagnosed with cardiomyopathy, a heart muscle disease which makes it harder for the heart to pump blood around the body.

He says he is proof that living a long time with a heart transplant is possible.

In 1984, The Netherlands had yet to perform its first heart transplantation, so cardiologist Albert Mattart referred the teenager to Harefield Hospital in England.

Janssen underwent transplant surgery in June that year after a heart became available following a tragic car crash in which two young adults died.

The life-saving operation was carried out by transplant pioneer Magdi Yacoub.

"I consider that day more important than my birthday," said Janssen, who is now 57, married with two sons and a keen glider pilot.

"I've never really looked this far ahead."

While he is fit and healthy, his heart medication causes side effects and in recent years he has had to slow down.

"I still do more or less what I want (but) at a different pace," he said.

The average life expectancy for heart patients after a transplant is 16 years, according to Janssen's current cardiologist, Casper Eurlings.

Guinness World Records officially recognized Janssen's achievement of living for 39 years and 100 days after receiving his transplant.

The previous record was 34 years and 359 days set by Canadian Harold Sokyrka in 2021, according to Guinness.

Transplant patients "need to maintain a healthy lifestyle and be active. That's what Mr Janssen did," Earlings said.

Yacoub has since thanked Janssen for his achievements and dedication to global health.

"But it's really me who should be thanking him," Janssen said.