Vice President Dick Cheney, 60, checked himself in and was hospitalized in Washington on Monday to clear a partly blocked artery after he complained of chest pains. "Strictly a precautionary measure," President George W. Bush, assuaging fears about Cheney's condition, told reporters. Doctors at George Washington University said that a coronary artery that was opened last November had narrowed again by 90% because of scar tissue and that the tube was reopened with a balloon angioplasty. They added that he did not suffer a new heart attack (he has had four in the past). Cheney's cardiologist, Dr. Jonathan S. Resiner, said that Cheney is likely to be released from the hospital on Tuesday and resume his vice-presidential duties later this week.