In early July 2011, founding member Fatt developed arrhythmia and underwent "urgent but routine" heart surgery, when he was fitted with a pacemaker after feeling unwell for several weeks and blacking out. He missed the group's US tour as a result, after not missing a show in 20 years. Also in mid-2011, the Wiggles celebrated their 20th anniversary with circus-themed shows and performances throughout Australia and the outback in a circus tent, as well as a "physically grueling" birthday-themed tour of 90 shows throughout Australia, which Paul Field called "one of the biggest of their careers". Sydney's Powerhouse Museum commemorated the group's anniversary with an exhibit that displayed Wiggles memorabilia.