A Bristol hospital's "continued system failure" contributed to the death of a patient, an inquest jury has ruled.
John Stratton was wrongly given an overdose of Heparin, an anti-blood clotting drug, at Bristol Royal Infirmary in January 2004.
Mr Stratton, 57, of Easton-in-Gordano, in North Somerset, later died from a brain haemorrhage.
The inquest heard the hospital had been busy and staff were under pressure. A narrative verdict was returned.
The inquest was told that when Mr Stratton was admitted to hospital after suffering a heart attack, staff nurse Kelly Cousins told a fellow nurse to administer 1,400 units of Heparin per hour.
This was over the maximum dosage. The error was noticed by a nurse after Mr Stratton's transferral to the hospital's coronary care unit, but the inquest was told she forgot about it.
'Lack of intervention'
Staff nurse Cousins, who admitted misjudging the dosage, said: "There was the immense pressure of management problems placed on me."
Siobhan Goodrich, for the United Bristol Healthcare Trust, accepted an overdose was given but argued this had not caused Mr Stratton's death.
Consultant histopathologist Dr Edward Sheffield carried out a post-mortem examination and concluded Mr Stratton's brain haemorrhage was due to the anti-clotting treatment.
The jury said hospital staff were working under extreme pressure and this resulted in nursing errors but it did not excuse the lack of staff intervention which could have prolonged Mr Stratton's life.
"The continued system failure, combined with the increased dose of Heparin, contributed to Mr Stratton's death," the jury said.
In a statement, Lindsey Scott, the United Bristol Healthcare NHS Trust's director of nursing, said that however good the staff and systems at the hospital were, there was always room for human error.
"We have learnt from this case and implemented changes to further reduce the opportunity for human error," she said.