Many young transplant patients move from Great Ormond Street Hospital for Children (GOSH) to have their adult care at Harefield.
The two hospitals work together to ensure young people are familiar with their new services, and are ready to move on from GOSH.
Special events give the young patients the chance to become acquainted with their new clinical care and have a tour of Harefield Hospital.
They also give young people a chance to say goodbye to their GOSH clinicians, who attend to offer support and formally have over their care.
At this year's event Olivia Cotter, 17, and Ella Armitage-Brown, 16, were among the patients who attended. The girls have been friends since they were in hospital together as toddlers.
Olivia, who had a heart transplant when she was two years old, after experiencing cardiomyopathy (a disease of the heart muscle) with secondary pulmonary hypertension (a type of high blood pressure that affects the arteries in the lungs and right side of the heart) said: "I feel ready to move on. Great Ormond Street has been great, but it is a children's hospital and I'm no longer a child."
Ella, who also had a heart transplant because of cardiomyopathy, added: "The staff have been very thorough. I've found it helpful and so has my mum."
Ben Sporle, 18, also diagnosed with cardiomyopathy, had a heart transplant in 2011. Ben has significant learning disabilities and needs extra support to understand his conditions and make decisions about his care, so ensuring a smooth transition is vital. Ben's mum Kerry Adamson said: "This day has been really positive for us. The staff at Harefield can begin to get to know Ben and understand his specific needs."
Dr Helen Spencer, a respiratory physician from GOSH who specialises in cystic fibrosis, added: "This is an emotional time. We have often looked after these patients their whole lives. It feels like family. Transition is a big deal - for all of us."
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