Children facing heart surgery in Bristol could be at risk because of a lack of specialists, a report claims.
Ash Pawade said the trust tried to stop him speaking out
It comes after baby Abbie Hattam died in May 2006 when a member of staff made a mistake during a heart operation.
An inquiry into her death said there were not enough blood circulation specialists, and now a report has found there is still a shortage.
Bristol's Children's Hospital said it has a plan for adequate cover and no children were at risk.
After Abbie's death an investigation said there were not enough perfusionists - blood circulation specialists who operate heart and lung bypass equipment during surgery.
And now a report, which was commissioned by the United Bristol Healthcare Trust (UBHT) as part of its programme of review and improvement, said that while results were still good, there was still a shortage of perfusionists at the hospital which meant the few there had to cover both adult and child theatres with "potential conflict".
Ash Pawade, head of the cardiac unit at the Children's Hospital, is leaving over his claims the trust tried to stop him speaking out about the shortage.
He told the BBC: "I maintained throughout the inquest that there were critical shortages within the perfusion department.
"Management maintained the stance that that wasn't an issue. Things finally came to a head during the weekend after Abbie's inquest.
"Bad things were conveyed to me from somebody high up within the trust. Vile things which I can't repeat for legal reasons.
"I felt very vulnerable and psychologically that broke my back."
The trust denied it tried to intimidate Mr Pawad and said he was leaving on grounds of ill health.
UBHT spokesman Dr Jonathan Sheffield said: "Mr Pawade took out a grievance about something that actually when reflected upon in the grievance it was him that contacted the individual concerned out of hours at that person's home address.
"We are puzzled why he believes that that should be an example of intimidation."
The Paediatric Cardiac review also criticised management for the way they handled events surrounding Abbie's death and said morale was still low.
It said Mr Pawade's departure gave an impression of a surgical unit that lacked direction and the lack of perfusionists could put the small number of patients who needed heart bypasses for days on end at risk.
The review concluded there was significant concern that good results were masking a number of problems, which if not resolved, will impact on patient care.