A baby whose death along with three others caused the suspension of heart surgery at a hospital died from natural causes, an inquest has ruled.
Nathalie Lo was 23 days old when she died after having surgery at Oxford's John Radcliffe Hospital last December.
Children's heart operations were suspended at the unit in March after three other babies subsequently died.
Recording a narrative verdict, the coroner said Nathalie died despite her treatment and not because of it.
The other three deaths will not be subject to inquests.
In July, a report by the South Central Strategic Health Authority recommended heart surgery should remain suspended at the hospital.
It said surgeon Caner Salih, who operated on all four babies, was not to blame for the deaths but found there were problems with his induction and mentoring.
Mr Salih told the inquest in Oxford there were no problems in the unit at the time of Nathalie's death.
He said that although there had been a postponement of her operation due to equipment, on the day of the operation everything was in place.
"At the time of the surgery I had the right equipment for the procedure," he said.
"There were no questions in my mind, not just in Nathalie's case but in any of the procedures I have done, that any of the procedures I have done were compromised by not having the right equipment.
"I would simply not have done it."
Asked about the atmosphere at the unit, Mr Salih - who was consultant paediatric cardiac surgeon at the hospital but now works at Guy's and St Thomas' Hospital in London - replied: "We were happy, we were a team. We had mutual respect for each other and we still do."
Nathalie was born on 29 November and weighed 7lbs 5oz (3.3kg) but seven hours after her birth medics noticed she had gone "blue".
She was diagnosed with a rare abnormality of the heart valve which, the inquest heard, was similar to a condition called Ebstein's malformation.
About two weeks later she underwent a procedure that was "common" for a number of heart problems and Mr Salih inserted a tube between the aorta and into the right pulmonary artery.
She was returned to intensive care in a stable condition but the surgeon was called a few hours later to find the baby in difficulties and she was later pronounced dead.
Mr Salih said: "We were at a loss to explain exactly what had happened."
He told the inquest he would not have treated the baby any differently in hindsight.
Coroner Nicholas Gardiner said there was no evidence Nathalie died because of her surgery.
He said: "It would be possible for me to record a verdict that she died of natural causes but I think it's necessary to expand on that to a rather greater extent.
"She was born with a congenital abnormality of the heart and possibly other less significant abnormalities.
"Appropriate surgery was undertaken but for reasons that are not entirely understood this did not produce the desired effect."
Speaking after the inquest, spokesman for the family Gayle Rossiter said: "As a family we would like to thank everyone at the hospital who was involved with Nathalie's care.
"We wanted to know why she died and although it's not exactly clear why, we have had a full explanation today.
"The family has been through a very difficult time and we are now relieved that this is all over."
A national review of paediatric heart centres in England said earlier this month that heart surgery should stop at the hospital, concluding it was the least likely out of 11 centres in England to meet new quality standards.
Its full recommendations are due early next year, but it is likely to say that the four or five smallest centres should stop carrying out operations.