A baby died at Birmingham Children's Hospital after "serious failures", a coroner has ruled.
Hayley Fullerton suffered heart failure following corrective surgery in November 2009, one month after her first birthday.
Recording a narrative verdict following an inquest into Hayley's death, Aidan Cotter, coroner for Birmingham and Solihull, said: "The failures by a number of the staff at Birmingham Children's Hospital were serious but not gross."
He said he could only make a finding of neglect if there had been a "gross" failure to provide medical attention .
Following the verdict, Hayley's mother, Paula Stevenson, said that she planned to sue the NHS over her daughter's "preventable and predictable" death.
She said: "Today is Hayley's day - I have been waiting three years to speak up.
"Hayley died like an abandoned animal - nobody listened to me while Hayley was dying and nobody listened to me when Hayley was dead."
Ms Stevenson, who flew to the UK from Australia to attend the hearing with Hayley's father Bobby Fullerton, added: "Our entire family has been completely devastated by what happened and continue to grieve for Hayley.
"I still cannot understand how trained medics could ignore the fact that she was slowly deteriorating before their eyes.
"They had seven days to spot that something was seriously wrong but all those precious opportunities were missed."
Hayley was born with a condition that restricted blood getting from her heart to her lungs.
After an operation at another hospital, she was sent to Birmingham for corrective heart surgery.
The operation was a success, but complications set in when Hayley's right lung collapsed.
Ms Stevenson, told the coroner's court earlier this year: "I was hoping she would be put in intensive care.
"I was waiting and waiting for someone to come so I was very aware and alert. I was telling her sorry I could not get help."
She also claimed that her child had been failed "abominably" and said her experience at the hands of some staff has been "brutal".
Ms Stevenson, who is originally from Northern Ireland but now lives in Australia, went on to allege that she gave a nurse a £100 gift voucher in an effort to secure better care for Hayley.
"I truly believe if the medical teams had listened to me and my parents, Hayley would still be alive today. They turned their back on her. She was overlooked and neglected," she said.
In an internal review of Hayley's death, the NHS found that a "hierarchy" among medics deterred junior staff from referring Hayley back to a paediatric intensive care unit in the days before her death on November 11.
In a statement issued after the coroner's verdict, the Birmingham Children's Hospital NHS Foundation Trust said: "When Hayley died we recognised that some of her care fell below our usual high standards and for this we offer a heartfelt apology for the distress that has been caused.
"We've taken all the steps possible to learn from this."
Ms Stevenson has now set up a website, heal-trust.org, which campaigns for the NHS to use Rapid Response Teams, which families, friends or patients can call if they feel their concerns over treatment aren't being heeded.