Prince Philip, the 99-year-old husband of Queen Elizabeth, underwent a successful procedure for a pre-existing heart condition on Wednesday, Buckingham Palace said Thursday.

Prince Philip was hospitalized on February 16 after feeling unwell to receive treatment for a nonspecific but not coronavirus-related infection, Reuters reported.

On Monday he was transferred to another hospital in central London, and the palace was then informed that his treatment for the infection would continue.

“The Duke of Edinburgh yesterday underwent a successful procedure for a pre-existing heart condition at St Bartholomew’s Hospital,” the palace said, using Philip’s formal title.

“His Royal Highness will remain in hospital for treatment, rest and recuperation for a number of days,” the statement said.

Since his hospitalization on February 16, the Duke has only been publicly visited by his son and heir Prince Charles.

The 94-year-old Queen remained at Windsor Castle, west of London, where the couple stayed during the COVID-19 pandemic, and continued in her official duties last week.

The Queen and Philip received the first dose of the coronavirus vaccine.

Prince Philip, who is from Greece and turns 100 in June, has required hospital treatment several times over the past decade for a relapse of his bladder infection.

On Christmas 2011, he underwent surgery to clear a clogged artery in his heart after he was rushed to the hospital with chest pains.