Japan's Imperial Household Agency says Empress Emerita Michiko has been diagnosed with heart disease.
The 84-year-old Empress Emerita underwent a heart examination on Saturday after a blood test showed an increased level of a cardiac hormone called BNP, which points to a higher risk of heart failure.
Agency officials say Saturday's test revealed that the Empress Emerita has moderate tricuspid valve regurgitation --- a disorder in which the valve does not close tight enough each time the heart contracts.
The Empress Emerita was also found to have an irregular pulse.
The officials say the test results indicate stress has increased the load on her heart. They say it's necessary for her to avoid stress in daily life, as well as to continue regular health checkups.
From Tuesday, the Empress Emerita is set to begin a three-day visit to Kyoto as scheduled, accompanying Emperor Emeritus Akihito as part of his abdication rituals. The itinerary includes a visit to the mausoleum of Emperor Meiji.
The Empress Emerita is also scheduled to undergo cataract surgery on June 16 and 23 at a hospital in Tokyo.