The now-abandoned review created rivalry between Leeds and Newcastle hospitals and a “strained relationship” between medics.
The criticisms were made in a long-awaited report into the temporary suspension of surgery at the Leeds General Infirmary unit last year.
It also found that a legal case launched by Leeds campaigners caused tension, while a consultant from Newcastle said they would doubt the accuracy of patient notes written by Leeds.
The reports’ authors call for a rebuilding of trust and confidence, saying “NHS England should act to dispel the almost morbid sense of spectatorship and foreboding that hangs over these services”.
Mike Bewick, deputy medical director of NHS England, told The Yorkshire Post that efforts were being made.
“Already we’ve started a dialogue between the two centres,” he said. “We will be doing this more frequently to make sure professional differences are put to bed and they can work together to provide a seamless service.”
The suspension of surgery came after concerns about mortality rates at the LGI unit and doctors from the Newcastle unit had given NHS heads a dossier of 14 Leeds cases which they said showed issues.
One of the newly-published reports found there were issues with risk assessments in two and with communication in five.
No evidence was found to support criticisms that Leeds doctors were reluctant to refer patients to Newcastle or anywhere else.
The report, by private firm Verita, said the allegations raised by Newcastle doctors were “not whistleblowing”, there were “inconsistencies” and the North- East medics should have made it clearer that they were repeating concerns of other people.
And the authors said in only two of the 14 cases did they fully agree with the accuracy of the case summaries written by the Newcastle trust.
Dr Yvette Oade, chief medical officer at Leeds Teaching Hospitals NHS Trust, said: “We recognise that in a small number of specific instances over a 10-year period, the report finds our unit did not match the high standards our patients rightly expect – this is not acceptable and we apologise to those families.
“Significant improvements have already been made at the unit over the last 18 months.”
A spokesman for Newcastle upon Tyne Hospitals NHS Foundation Trust, which runs the Freeman Hospital where their children’s heart surgery unit is based, said they “exercised freedom and a responsibility to patients and the NHS to fulfil the duty of candour, that for whatever the prevailing circumstances, were not receiving the appropriate care and treatment”.
Supporters of the Leeds unit said the reports vindicated their backing for the service.
Sharon Cheng, CEO of charity the Children’s Heart Surgery Fund, said: “The Verita report finally provides the balanced investigation and viewpoint that clinicians and families have been waiting for.”
Lindsay Clarkson, mother of Leeds patient Renee-May Lock who had an operation there in July, added that she “couldn’t speak highly enough” of care.
But families who had raised concerns about standards said they were “unhappy” about the findings. Michelle Elliott, from South Yorkshire, said: “Had the Freeman Hospital not operated, my child would be dead now.”