Akihito returned to the palace on Sunday after the tests and has scheduled the surgery for Feb. 18, the Imperial Household Agencysaid.

A medical team from the University of Tokyo and Juntendo hospital will carry out the surgery at University of Tokyo Hospital, as his heart condition had worsened compared to tests a year ago, the agency said.

The palace's statement said the surgery will help the emporer enjoy a relatively active life

Akihito has had various health problems in recent years, including pneumonia and prostate cancer. He has cut back on public duties but still appears regularly at events.