A grandmother died after a heart valve was put in upside down during routine surgery, causing massive internal bleeding.
The operation caused irreversible damage to Sheila Hynes' heart and she never came round from surgery.
A second operation to try and get her heart working failed and the 71-year-old died in intensive care a week later.
Newcastle Upon Tyne Hospitals NHS Foundation Trust, which runs the Freeman Hospital where the operation was carried out, has admitted that the error caused Ms Hynes' death.
Consultant surgeon Asif Raza Shah who led the operation still works at the trust.
The great-grandmother's daughter, Jan Hopper, from Haltwhistle, Northumberland, said the family have been left distraught.
"My life has been destroyed by what happened to my mother," the 55-year-old explained.
"She was a very active woman and loved nothing more than going on holiday.
"The week before her operation we had been in Tenerife as her sister Carol had just been diagnosed with pancreatic cancer.
"It was a bittersweet time and mum had wanted to get her own operation over with so she could care for her sister.
"My mother was the picture of health that week and I can remember saying to her, 'mum, you look absolutely stunning'.
"Nothing was more important to my mum than family and she loved spending time with all of us.
"She was the heart of our family."
Ms Hynes had undergone the surgery to try and improve her breathing, which was being hampered by inadequate blood flow.
Following the complications during surgery Ms Hynes said the family felt "completely ignored and left in the dark."
She continued: "It took three days before we found out there had been an injury to her heart - that was dropped into conversation by one of the doctors.
"We asked what on earth that was all about, they'd never mentioned it before. He said it had been punctured.
"Then a doctor mentioned to my son about a valve being put in the wrong way. We were immediately suspicious as nobody had said this before...
"We were told that putting the heart valve on the wrong way had caused her heart to balloon up and expand, and then when it contracted the wall of her heart was pierced on an instrument.
"We still haven't come to terms with what happened. It's been traumatic."
The hospital trust has admitted full breach of duty, and that the error which caused Ms Hynes' death was the insertion of the heart valve the wrong way.
A trust statement said: "Our thoughts are with Mrs Hynes' family at this difficult time and we would like again to offer our sincere condolences to them.
"Our staff always try to provide the best possible care to all of our patients. So we take the death of any of our patients very seriously.
"Sadly, when providing complex treatment there may be rare occasions when something unexpected happens, and in those circumstances we always carry out an in-depth investigation and we have done so in this case."
Ms Hynes' family have launched legal action, and Nicola Evans, from Hudgell Solicitors who are representing them, said she believes Ms Hynes' right to life was breached under the Human Rights Act.
She said: "This is an absolutely shocking case.
"A family has been robbed of a much-loved mother, grandmother and great-grandmother simply because a surgeon has not taken the care to ensure he has fitted a heart valve the right way up.
"The heart valve was placed in an inverted manner, preventing the blood from being able to flow out of the heart as it should, there was therefore distension and tearing of the left ventricle.
"This error was not actually identified by the surgeon himself at the time and was only discovered after another surgeon came in to assist and discovered it.
"Such was the scale of this error, we applied for the Inquest into Mrs Hynes' death to have further scope to investigate the circumstances under the Human Rights Act, which has been agreed by the coroner."
An inquest into the April 2015 death has been scheduled for later in 2017.