U.S. Vice President Dick Cheney left a Washington hospital Saturday after undergoing tests ordered by his doctor following shortness of breath he suffered earlier in the day, news reports said. Cheney, 63, was shown on U.S. television leaving the hospital with his wife, Lynne, and waving to reporters as he got into his motorcade. Cheney, who has a history of heart problems, underwent an electrocardiogram and other tests at the city's George Washington University hospital. The White House confirmed that Cheney went to the hospital after calling his doctor Saturday morning to inform him of the problems. "Everything looks great," said Mary Matalin, a spokeswoman for the vice president, before he was released. She told The New York Times Cheney went to the hospital on his own and walked in under his own power. Cheney returned Thursday night from a pheasant hunting trip in South Dakota with a cold that left him short of breath, Matalin said. His cardiologist, Dr. Jonathan Reiner, said Cheney's problems most likely were caused by a respiratory infection. "The vice president, complaining of a productive cough and shortness of breath, was evaluated at George Washington Medical Center today," Reiner said in a statement issued by the White House. "Tests ruled out any cardiac cause of the vice president's symptoms. Tests also ruled out pneumonia and other pulmonary causes. The vice president likely has a viral, upper respiratory infection." The result of the electrocardiogram, which measures the heart's electrical activity, was normal, and a readout taken from Cheney's heart defibrillator unit - a device implanted more than three years ago to monitor Cheney's heart rhythm - also showed that Cheney's heart was functioning normally, news reports said. The device gives doctors a three-month readout. President George W. Bush was informed of Cheney's visit to the hospital, and was apprised of the tests he underwent, news reports said. Cheney has had four heart attacks, the first occurring in 1978 when he was just 37 years old. None of the heart attacks occurred during his stint as vice president. Doctors implanted the defibrillator, which also is designed to slow his heart down if it begins beating rapidly, in 2001. Cheney was given a clean bill of health after his annual heart checkup in May, CNN reported. But he travelled frequently during the recent presidential campaign, including a trip to Hawaii.