Sen. John Warner (R-Va.) was released from a hospital Wednesday following two days of observation for a previously diagnosed heart condition.

In a statement issued by his office, Warner said his heart rate had returned to a normal rhythm and that he had responded positively to new medications and treatments for atrial fibrillation. He was admitted to the hospital Tuesday at the direction of the Capitol physician.

Atrial fibrillation occurs when the heart’s two small upper chambers “quiver” instead of beating effectively. The condition develops in 3 to 5 percent of adults over 65, according to the American Heart Association.