Sen. Johnny Isakson (R-Ga.) was hospitalized Monday for an irregular heartbeat, less than one week after the 65-year-old was treated for a bacterial infection. Isakson was admitted to Piedmont Hospital in Atlanta on Monday night after cardiologist Dr. Charles Brown III issued the latest diagnosis, according to a statement from the Senator's office. A second doctor had originally detected the irregular heartbeat when he treated Isakson's bacterial infection last week. Doctors also found a blood clot in Isakson's right calf, which according to spokeswoman Joan Kirchner developed as a result of Isakson "being sedentary for the past week while recovering from the bacterial infection." Isakson, currently serving in his first Senate term, is running for re-election this year.