Officials from the so-called Imperial Household Agency said a medical team from the University of Tokyo Hospital decided to operate on the 78-year-old monarch after recent tests showed that Akihito's heart condition had grown worse over the last year.
The surgery will help ensure the emperor enjoys a relatively active life, officials said.
Akihito has suffered numerous health setbacks including surgery for prostate cancer in 2003 and stress-related health issues in late 2008. He is still seen at numerous events but has cut back on his ceremonial public duties, such as offering speeches and meeting foreign dignitaries.
Despite ancient dynastic roots, the monarchy has changed with the times, to a certain extent. No longer is the emperor regarded as a living god, as was the case for centuries. Still, Akihito is a much-revered figure.
Although Japan's modern-day tabloids sometimes strike a gossipy tone when talking about members of the current royal family -- aggressively dissecting Empress Michiko's stress-related ailments, or the failure of her daughter-in-law, Crown Princess Masako, to produce a male heir -- there is rarely, if ever, a disrespectful word uttered of Akihito.
Following last year’s deadly earthquake and tsunami, Akihito delivered an unprecedented imperial pep talks to his people in which he urged calm, perseverance and solidarity in "the difficult days that lie ahead."
Akihito assumed the throne in 1989 following the death of his father, Emperor Hirohito.
After the emperor spent nearly three weeks in the hospital in 2011, Prince Akishino, who is second in line to the throne, called for debate on a retirement age for the head of state.
Under Japan's 1947 Imperial House Law, the emperor is succeeded on his death by a male relative. Crown Prince Naruhito is first in line to the throne, followed by his younger brother.
-- John M. Glionna
Photo: Japanese Emperor Akihito, right, is greeted by doctors on his arrival at University of Tokyo Hospital on Friday. Credit: Toshifumi Kitamura / Getty Images