More than 30 children who died after undergoing heart surgery in Bristol in the 1980s and early 1990s could have been saved, the Bristol Royal Infirmary inquiry was told last week.
But the hearing was also told that shortcomings could not just be blamed on the two surgeons at the heart of the tragedy.
James Wisheart and Janardan Dhasmana were found guilty of serious professional misconduct by the General Medical Council last year, after it found they had continued to perform complex heart surgery on young children when they should have known their death rates were too high.
But a review of 80 casenotes, selected from 1,800 children who had open or closed heart surgery at the hospital over 12 years showed that 'where the care was less than adequate, surgery does not feature very highly'.
Dr Eric Silove, a paediatric cardiologist at Birmingham Children's Hospital, said problems were also identified with diagnosis, treatment before surgery, the timing of operations and aftercare.
The inquiry took evidence last week on the data sources available to determine mortality and morbidity between 1984 and 1995.
Dr Paul Aylin, senior clinical lecturer at Imperial College school of medicine in London, said a study of hospital episode statistics suggested that children under 90 days old who underwent heart surgery at Bristol had a mortality rate of 63 per cent, four times that elsewhere.
Children aged 90 days to one year who underwent open heart surgery had a mortality rate of 20 per cent, three times higher than elsewhere.
He suggested that for all children under 16 years undergoing open and closed procedures, there were 35.3 excess deaths out of 67, although differing analysis produced a slighly lower figure.
The biggest problems showed up in just three procedures - operations to correct the transposition of the great arteries (switch operations), and to correct atrial ventricular spetal defects (AVSD) and atrial septal defects (ASD). These were the procedures at the heart of the GMC inquiry.
Gordon Murray, professor of medical statistics at Edinburgh University, said analysis of the UK cardiac surgical register showed 'the same areas of concern cropping up in other data sources'.
But the following day, Dr Silove said the casenotes review team raised concerns about diagnosis in 12 cases and concluded that in seven, 'wrong or incomplete diagnosis' could have affected the outcome. Delays were also identified before 21 procedures were carried out, and could have affected the outcome in six.
The inquiry has taken evidence about waiting-list problems, which struggled for a number of years to expand services to keep pace with demand against a background of financial constraints.
Dr Silove also said medical and anaesthetic post-operative care was 'less than adequate' following 19 procedures. One problem identified was poor nursing care of children in the intensive care unit .
The inquiry has also heard there were repeated calls to move paediatric cardiac surgery to Bristol Children's Hospital, to prevent children being placed in adult intensive care and then transferred to the children's hospital.
Brian Langstaff QC, inquiry counsel, asked Professor Stephen Evans, a consultant statistician: 'Would it be a mistake, then, to attribute the apparent difference in performance of Bristol compared with other centres to less than adequate surgery as opposed to possibly less than adequate care?'
'Yes, I think it would be inaccurate, ' said Professor Evans.