Former US vice president Dick Cheney has been admitted to the hospital in Washington DC after complaining of being uncomfortable, his spokesman said.
It is the latest health scare for the 69-year-old Republican, who has a long history of heart disease.
Mr Cheney was expected to remain at George Washington University Hospital over the weekend, said spokesman Peter Long.
It was not immediately clear whether Mr Cheney’s health concern was related to his previous heart troubles. He sustained his last heart attack, deemed a mild one, in February.
Mr Cheney was not feeling well yesterday and went to see his doctors. On their advice, he was admitted to the hospital for further testing.
Mr Cheney’s heart attack earlier this year was his fifth since age 37. A heart attack occurs when blood flow to the heart muscle is blocked. In that episode in February, Mr Cheney underwent a stress test and a heart catheterisation.
A face of his party for decades, Mr Cheney has remained a prominent voice of opposition to the Obama administration. His public career spanned decades, including service as defence secretary and White House chief of staff.
Mr Cheney had bypass surgery in 1988, as well as two later angioplasties to clear narrowed coronary arteries.
In 2001, he had a special pacemaker implanted in his chest. In addition, doctors in 2008 restored a normal rhythm to his heart with an electric shock. It was the second time in less than a year that Mr Cheney had experienced and been treated for an atrial fibrillation, an abnormal rhythm involving the upper chambers of the heart.
AP