The parents of Tiarna Middleton, the little girl who died while waiting for a heart transplant, have thanked the Freeman Hospital in Newcastle for all the help they gave their daughter.
Tiarna became the youngest person in the world to be fitted with an artificial heart.
She died on Monday, at just 18 days old. Gary Middleton and Sharney Gray say the hospital staff could not have done more:
Sally Johnson, director of organ donation and transplantation at NHS Blood and Transplant, said: "We would like to send our sincere condolences to Tiarna's family at this very difficult time following the loss of their daughter.
"It's so sad to hear that she didn't receive the vital organ she needed to give her a chance of life.
"It is always tragic when when anyone doesn't get the organ they need but, the sad reality is that until we are all prepared to agree to donate our organs of those of our children after death, people will sadly die waiting for a transplant.
"Current national guidelines for the diagnosis of brain death do not support donation from brain dead infants under the age of two months, so we would support the review of the current guidance in the light of medical advances and increased knowledge."
The father of baby Tiarna Gray, who died after waiting for a heart transplant, says the last 24 hours have been very difficult.
He told ITV News: "We are just trying to deal with it. Words cannot describe it really.
"We had to turn the machine off.
"The last 24 hours have been very difficult.
"Now I would like to start raising more awareness."
Tributes have been paid to baby Tiarna Middleton, the youngest patient in the world to be fitted witha Berlin Heart. Tiarna lost her fight after 18 days while waiting for a heart transplant.Her parents Sharney Gray and Gary Middleton were with her when she died on June 9.
– Rachael Brown via Facebook
People have been leaving messages on Sharney's Facebook page.
"Life can be so cruel. Thinking of you Sharney Gray and the rest of the family. RIP Tiarna xxxx"
– Sarah Carrick via Facebook
"My heart goes out to you, such heartbreaking news, a beautiful baby girl loved by so many."
Tiarna was born on May 22 and was suffering from congenital heart disease. She survived the first two weeks and became the youngest patient in the UK to need a heart transplant.She was fitted with a Berlin Heart while medics searched for a donor.
Since her birth Sharney, 22, and Gary, 25 have brought attention to current UK guidelines that mean babies under two months old cannot be organ donors.
– Gary Middleton, speaking before his daughter's death
"The next 48 hours following her operation are critical. We just want everyone out there to consider becoming an organ donor, I've signed up myself and if other people can do too that would be lovely."
Baby Tiarna Middleton, who last week became the youngest person in the world to be given a Berlin heart, has passed away at the Freeman Hospital in Newcastle
The 18-day-old baby girl was awaiting a heart transplant at the hospital.
The parents of a two-week-old baby, who is in urgent need of a heart transplant, are appealing to people sign up to the organ donor register.
Gary Middleton's daughter Tiarna is the the youngest baby in the world to be fitted with a mechanical Berlin heart, at Newcastle's Freeman Hospital.
Doctors on Tyneside say a Europe-wide appeal to find a new heart for a 15-day-old baby girl is becoming more urgent by the hour.
Earlier this week Tiarna Middleton became the youngest baby in the world to be fitted with a mechanical Berlin heart, at Newcastle's Freeman Hospital.
It acts as a second heart until a transplant can be arranged.
Her parents' plea for a donor has spread as far as New York.
However, an organ transport time limit of just five hours means the search is limited to Europe.
A baby has become the youngest in the world to be supported by a Berlin Heart device.
Tiarna Middleton, 14 days old, from Rowlands Gill in Gateshead was born on May 22 with an extremely rare heart condition.
It was decided she would not survive and doctors at the Freeman Hospital decided to use a new small Berlin Heart Ventricular Assist Device - which was delivered from The Berlin Heart Company in Germany where it is made.
On Tuesday, surgeon Massimo Griselli fitted Tiarna with this device which doctors hope can keep her alive until a donor heart is found.