Max George became "nervous" when doctors told him he had to have a second operation on his heart

He told The Sun on Sunday newspaper: "I thought I was on the road to recovery but when I was told I needed a second operation I was nervous, as pulling the pacemaker wires out of the heart wall risks bleeding on the heart.

"I didn't have a choice, though. I had to have it done.

"I was trying to get back to good health but was still having a flickering sensation for weeks after I had my pacemaker fitted and it was gradually getting worse and worse.

"When my heart rate went up, it was causing a shock in my heart which was making me jump all the time. My chest was shaking."

Just before Christmas, it was discovered that Max had been suffering from an atrioventricular block, which caused his heart to beat abnormally.

The 'Glad You Came' hitmaker was booked to go in for surgery again in mid-January, but became increasingly worried about it all and lost sleep the night before.

He said: "The night before, I was really nervous, I didn't sleep much.

"I was worried it could go wrong again and felt anxious that it could bleed out."

Max then needed to undergo a lung biopsy after doctors found enlarged lymph, and he was warned that the invasive operation could damage his vocal cords permanently.

He said: "The doctor did warn me there is a small chance that I could lose my voice. That was pretty worrying, but I decided I needed to take the risk. The biopsy was pretty gnarly, it's a camera with prongs on the end that goes down your throat. It was painful. The recovery was tough, I had chest pain and was coughing up blood for five days."

In the end, Max received the all-clear, but he admitted that the "worst part" of the whole ordeal was seeing the pain it had caused his parents.

He said: "The worst part for me is seeing my parents go through this. My mum has found it traumatic. I've tried to hold back from being upset in front of them. I feel helpless and responsible."