But as he turned 15 his condition deteriorated and a heart transplant operation was carried out last month.

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In a news conference on Monday, the Birmingham hospital's medical director Dr Dave Rosser said everything had gone "very well" in Saturday's operation and said the teenager's condition was continuing to improve.

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The star, whose hits include I'm Outta Love, also suffers from the bowel condition Crohn's disease and had an operation for this at the age of 13 for the illness.

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