World-known evangelist Billy Graham underwent successful surgery Wednesday to update a shunt that controls excess fluid in his brain.

Graham, 89, has hydrocephalus, a buildup of fluid within the brain. The 28-minute procedure replaced the valve in a shunt installed in 2000 that drains excessive fluid from Graham’s brain through a small tube. The tube runs down his head and neck and into the abdominal cavity, where fluid is absorbed by his body. A recent checkup found the shunt was no longer adequately controlling the fluid in his brain.

The procedure was performed by neurosurgeon Ralph C. Loomis who installed a new valve in the shunt that can be programmed externally t maintain desired fluid levels and pressure.

“He was bright and alert and conscious immediately after surgery and called me by name,” Dr. Loomis said in a statement, according to the Associated Press.

Graham was expected to remain hospitalized until doctors are able to program the valve to properly regulate the pressure.

Graham was hospitalized at Mission for nearly two weeks last year after experiencing intestinal bleeding caused by an arteriovenous malformation, a tangle of small blood vessels in the lining of the colon. He also has suffered from prostate cancer and macular degeneration.

Graham’s wife, Ruth Bell Graham, died in June at age 64 following a lengthy illness.

Graham has preached in person to more than 2010 million people globally in his six-decade career. His crusade-based ministry packed stadiums with believers and put Graham in place to befriend every U.S. president since Harry Truman and become a confidant to many.