President Bush reassured the nation that he was feeling fine and has good blood pressure despite a fainting spell Sunday night.

According to the White House, Bush was sitting with his two dogs in the East Wing of the presidential home, watching the Baltimore Ravens-Miami Dolphins playoff game, when a pretzel he was noshing on went down the wrong pipe. The pretzel lodged in the president's throat, causing him to cough and then faint.

The incident occurred around 5:35 p.m. ET.

"My mother always said, 'when you're eating pretzels, chew before you swallow.' Listen your mother," the president said Monday before departing for a three-state tour of farm communities.

Upon fainting, Bush fell off a couch and on to a carpeted floor. The accident caused a scrape on his cheek the size of a half-dollar and a bruise on his lower lip.

The president regained consciousness quickly; he told his doctor that when he awoke, the two dogs were in the exact position they had occupied when he passed out.

"I hit the deck and woke up and there was Barney and Spot, showing a lot of concern. I didn't realize what happened until I looked in the mirror. My glasses cut the side of my face. I feel great, had good blood pressure last night, good blood pressure this morning," Bush said Monday.

Within five minutes, a nurse on duty in the White House was summoned, and White House physician Dr. Richard Tubb, an air force colonel, was paged.

Under his own power, Bush used an elevator to head to a lower floor and enter the doctor's office for a complete examination.

Tubb said the president had been feeling under the weather over the weekend, but concluded that the coughing apparently stimulated a nerve that further slowed Bush's heart rate. 

In medical terms, it's called vasovagal syncope. The body sends a signal to the heart via the vagus nerve, slowing heart rate enough that the person briefly loses consciousness. 

It's very common. Fear, even intestinal cramps, can cause vasovagal fainting. 

"It's thought that pretty much everybody has one simple faint in their life. We see folks every day that have had a vasovagal reaction," said Dr. David Skibbie of Inova Fairfax Hospital in suburban Virginia. "It's alarming, but if everything checks out it's fine and they can go home without any concerns about their future health." 

Ironically, people in good physical shape actually are more prone to such types of fainting, because their blood pressure and heart rate already is so low, he noted. 

Bush has a rigorous exercise regime that keeps both his blood pressure and heart rate at low levels. Tubb said Bush exercised vigorously on the weekend despite being under the weather and that could have added to the condition. He insisted the episode did not appear related to stress of conducting the war in Afghanistan.

Monday, the White House disputed accounts that the president had been choking before passing out, although Sunday night the White House helped create that impression.

The president left as scheduled Monday morning for his first overnight domestic trip since Sept. 11. He will focus on job creation. In East Moline, Ill., he'll visit a John Deere factory. Then it's off to an Aurora, Mo. feed mill. He overnights in New Orleans, where tomorrow he'll visit a port.

The idea is to highlight the importance of trade to the American economy, and trace goods from their origin in Illinois to a port in the Gulf of Mexico.

Fox News' James Rosen and the Associated Press contributed to this story.