King Bhumibol Adulyadej of Thailand has undergone heart surgery, the Thai Royal Household Bureau announced.
The 88-year-old king, the world’s longest-reigning monarch, has had a lengthy spell in hospital in Bangkok and has not been seen in public for months.
King Bhumibol is widely revered and seen as an arbiter in the country’s divided political arena.
The king was treated for narrowing of the arteries with “satisfactory results”, the palace said in a statement.
Doctors performed a procedure known as balloon surgery to widen the arteries on June 7 after tests had shown insufficient blood in the heart muscles, the statement said.
In the past month, King Bhumibol has also been treated for a buildup of fluid surrounding the brain and a swollen lung.
An X-ray on June 4 showed less fluid around the brain, the statement said.
King Bhumibol’s health is closely watched in Thailand as he is seen as a unifying symbol and pillar of stability in a society that has suffered increased political divisions and violence.