A seven-year-old boy recovering from heart surgery died after suffering a "sudden catastrophic haemorrhage", a coroner ruled today.

Avon Coroner Maria Voisin said she had heard no evidence that there had been any "gross failures" in the care Luke Jenkins, from Cardiff, received at Bristol Children's Hospital.

Ms Voisin recorded a narrative conclusion, ruling that Luke died from a combination of a hypoxic ischemic brain injury, post-operative bleeding and a congenital heart defect.

She also said that having heard evidence of changes the hospital trust had made in the wake of Luke's death she would not be writing a report to prevent future deaths.

Warminster couple Yolanda and Steve Turner, whose four-year-old son Sean died just weeks before Luke on same ward at the hospital, attended the inquest several times over the seven days.

Sean died in March last year, six weeks after corrective surgery for a congenital heart condition, while Luke died just weeks later in April, following surgery to correct a heart complaint he had suffered since birth.

During the inquest, the coroner heard from more than 30 witnesses, including many of the doctors and nurses who treated Luke.

His parents, Stephen Jenkins, 31, and Faye Valentine, 28, spoke of their concerns about staffing levels and the amount of care he was receiving on Ward 32.

A report published last year revealed a series of errors - including bank holiday staff shortages and staff not knowing where to find resuscitation equipment after he suffered a cardiac arrest - that contributed to Luke's death.

The ward was also the subject of an unannounced inspection by the Care Quality Commission (CQC), the patient safety watchdog.

The CQC issued a formal warning to the hospital, declaring that it failed to meet three essential standards of patient safety, on staffing levels, staff training and support, and overall care and welfare of patients.

The inquest heard that following Luke's death numerous changes have been made by the University Hospitals Bristol NHS Foundation Trust to patient record keeping, staffing levels and protocols for responding to parents' concerns.

Luke was born in November 2004 with a congenital heart defect and underwent a series of operations during his short life.

During surgery in Bristol in 2009 he suffered damage to his spinal cord and his parents were told he had become quadriplegic.

Over the next two years the little boy battled through his difficulties from being paralysed and managed to walk again with the use of a frame.

His family returned to Bristol for the procedure because they trusted his surgeon Andrew Parry, who had performed two previous operations on Luke.

In the aftermath of Luke's death it emerged that Mr Parry had supervised Luke's final operation, but a colleague carried out the procedure.

The inquest at Flax Bourton heard Luke underwent successful corrective surgery on March 30 and was expected to make a full recovery.

His parents thought he would be spending three days on a high dependency unit but was transferred to Ward 32 the following day.

Nurses told the inquest that there was "quite a lot of stress" from working on the ward but insisted staffing levels did not compromise Luke's care.

Luke's parents noticed that his chest drain, which collected fluid from his lungs and chest cavity as a result of the surgery, was filling up with a significant amount of blood and fluid.

On April 2 Luke returned to the operating theatre to have an additional chest drain fitted but he continued to lose fluid.

The inquest heard that although medics admitted there was blood in the fluid, they said there was no evidence of fresh bleeding and that it could have come from capillaries around the heart weakened by surgery.

They said that in their opinion the fluid in the drain was a mix of possibly old blood and fluid found in various body cavities.

The inquest heard that the drainage of fluid from the body in patients following heart surgery at times could be "significant".

Doctors took the decision not to return Luke to surgery and open up his chest to check for any bleeding.

Zoe Farr, an outreach nurse, said she was concerned about the amount of fluid draining from Luke's chest and asked two senior staff four times to check on him before they visited his bed.

On April 6 Luke began complaining of severe chest pains and while an echocardiogram machine was being collected he suffered a cardiac arrest, with his heart stopping for more than 40 minutes, and then brain damage.

Three days later his parents took the heartbreaking decision to switch off Luke's life support machine after having him christened.

Consultant cardiac surgeon Serban Stoica, who carried out the Fontan operation on Luke, said he could not explain why the boy died.

Dr Duncan Macrae, a consultant in paediatric intensive care at Royal Brompton Hospital in London, gave evidence to the inquest as an expert. He described the bleed Luke suffered on the morning of April 6 as "very sudden".

The inquest heard that had the artery been damaged during surgery, "immediate bleeding" would have been seen.

But Dr Macrae added it was "possible" that the damage to the mammary artery was done during the operation on March 30.

A post-mortem examination concluded that Luke had died from a hypoxic ischemic brain injury, post-operative bleeding and a congenital heart defect.

Up to 10 families are believed to be taking legal action against the University Hospitals Bristol NHS Foundation Trust over its treatment of newborn babies and young children who died or suffered complications during treatment on Ward 32.

The trust is accused of a catalogue of neglect and mistreatment of babies and children with heart problems, over a four-year period from 2008.

The claim is thought to centre on up to 10 families - including seven whose children died following treatment at the hospital. They include the Turners, who claim their son Sean's case is not isolated.

The inquest into the death of Sean has been scheduled for January 14 next year.