Christine Mann, the hospital's matron and nursing services manager, apologised to them, saying one reason they were excluded was because of staff shortages.
She also apologised for the parents, feeling they were not given enough information about discussions involving Dylan.
She said: "I have no excuses.
"They should have been allowed to be with him throughout all the resuscitation.
"They should most definitely have been with him.
"We learnt from this case about communicating and documentation.
"We clearly didn't communicate with Dylan's family effectively when staff were adjusting and silencing his monitor.
"We should have been more clear to the family about what was happening at that time."
Though Dylan, of Uxbridge, was being treated at Hillingdon, Dr Barakat was in telephone contact with a children's heart specialist from Great Ormond Street Hospital to discuss the case.
Dr Shankar Sridharan, the medic from Great Ormond Street Hospital, said though an ECG would have helped, there was no reason to conduct one at the time.
He said that when he was contacted about Dylan's case on the day before he died there was no clinical evidence the youngster needed an ECG.
Dr Sridharan said: "If someone called this weekend with the same information we would do the same thing.
"We wouldn't arrange an urgent transfer if there were no clinical signs."
The specialist added, with hindsight, an ECG would have been beneficial and would have suggested other drugs might have benefited the child.
He also said Dylan had an ECG 12 months earlier which he had seen and which reassured him.
Edited by Sunita Patel-Carstairs
Source : http://telegraph.feedsportal.com/c/32726/f/568612/s/300865f7/sc/8/l/0L0Stelegraph0O0Chealth0Chealthnews0C10A2477610CToddler0Ewho0Edied0Ein0Ehospital0Ehad0Eno0Eheart0Etest0Eas0Eit0Ewas0Ethe0Eweekend0Bhtml/story01.htm