An inquest into the death of a four-year-old boy at Bristol Children's Hospital will begin today.
Sean Turner died in March 2012 from a brain haemorrhage after previously suffering a cardiac arrest while a patient at the hospital - six weeks after he underwent vital corrective heart surgery.
Sean's parents, Stephen and Yolanda from Warminster, Wiltshire, claim their son's death was not isolated and other children with heart problems died at the hospital.
In November last year, Avon Coroner Maria Voisin recorded a narrative conclusion at the inquest of Luke Jenkins, seven, who died in April 2012 following surgery there.
Mrs Turner, along with her husband, claims children on Ward 32 - where both Luke and Sean were treated - are in danger due to staff shortages and a lack of proper training.
Speaking ahead of her son's inquest, Mrs Turner told the Wiltshire Times she was concerned it could also result in a narrative conclusion.
"We feel that it was obvious from the first week after Sean's surgery that there were things that could have been done," Mrs Turner said.
"We believe he would still be here if something had been done sooner."
Following the coroner's conclusion, Luke's mother Faye Valentine, 28, said she believed the hospital could have done more to save his life.
Miss Valentine, from St Mellons, Cardiff, claimed Ward 32 was understaffed and accused doctors and nurses of ignoring her concerns.
"It's been hard listening to what they've said," Miss Valentine said. "There's quite a few we disagree with and that's been difficult to listen to but we've had to do it to come to where we are now."
T he coroner ruled she had not heard evidence of "gross failures" in Luke's care and recorded a narrative conclusion, ruling that he died from a combination of hypoxic ischemic brain injury, post-operative bleeding and a congenital heart defect.
"Whereas Luke was in a dependent position due to age and illness, I have heard no evidence that a gross failure has led to or contributed to his death," she said.
Up 10 families, including those of Luke and Sean, are believed to be taking legal action against the University Hospitals Bristol NHS Foundation Trust over treatment on Ward 32.
Two more inquests involving the hospital are scheduled for February and March.