"I feel fine," the 63-year-old vice president said as he walked out with his wife, Lynne. Cheney smiled and waved. "Sorry we ruined your Saturday," Mrs. Cheney said. "We're great."
CBS News Correspondent Joie Chen reports the vice president left the hospital late Saturday afternoon as he arrived -- under his own power - and in his own limosine -- no ambulance needed.
A pacemaker implanted in Cheney's chest three years ago indicated no irregularities during the past 90 days, said Mary Matalin, a spokeswoman for the vice president. The device gives doctors a three-month readout. She said an electrocardiogram, which measures the heart's electrical activity, showed no change.
She said Cheney probably had a viral upper respiratory infection but there was no cardiac or pulmonary problem behind his shortness of breath.
The Early Show medical correspondent Dr. Emily Senay says shortness of breath is not to be taken lightly: "It is difficult to speculate on why Cheney needs emergency room treatment at this time. However, shortness of breath is a serious complaint and needs evaluation, especially when there is a history of cardiac disease, as there is in Cheney's case."
Cheney, who has had four heart attacks, although none as vice president, returned Thursday night from a pheasant hunting trip in South Dakota with a cold that left him short of breath, Matalin said.
The vice president, who joined President Bush on Friday for meetings with British Prime Minister Tony Blair, felt fine otherwise, but his cardiologist, Dr. Jonathan Reiner, recommended as a precaution that he go to George Washington University Hospital for tests.
"Everything looks great," Matalin said before Cheney was released. "He's walking around from room to room in his street clothes just waiting for the blood work."
She said Cheney was driven in a motorcade from his residence a few miles from the hospital and walked in under his own power.
"He was doing this just as a precaution," Matalin said, adding that Cheney did not need an ambulance.
The president was notified by his chief of staff, Andy Card, shortly after Bush returned from a bike ride Saturday at a Secret Service training facility outside Washington, White House spokesman Ken Lisaius said.
In June 2001, Cheney had a pacemaker implanted in his chest. At his annual heart checkup on May 11, doctors determined the pacemaker, called an implantable cardioverter defibrillator, was working fine and had never needed to assist his heart.
The device is designed to activate automatically if needed to regulate the patient's heartbeat.
Ahead of the fall presidential campaign, Cheney dismissed speculation that his health might keep him from running again with Bush. He said his health had been good and that he could not think of any circumstances that would prompt him to decline the role. He kept up a heavy travel schedule during Bush's re-election campaign, often traveling with his wife.
His first heart attack occurred in 1978, when he was 37. He had a second in 1984, and after suffering his third heart attack, in 1988, Cheney had quadruple bypass surgery to clear clogged arteries.
On Nov. 22, 2000, Cheney suffered what doctors called a "very slight" heart attack and had an angioplasty to open a clogged artery.
Cheney was back in the hospital on March 5, 2001, after complaining of chest pains. Doctors performed another angioplasty to reopen the same artery.
After his fourth heart attack, Cheney quit smoking, began regular daily exercises for 30 minutes on a treadmill and said he began watching his diet.