we're now learning dick cheney's hospital stay after chest pains is more serious than originally thought. the former vice president actually had a heart attack. it's cheney's fifth heart attack. doctors gave him a stress test and inserted a catheter. his office says cheney is feeling good and should be out of the hospital soon, but they're not saying when. a source tells cnn that vice president joe biden and former president george w. bush both called dick cheney with well wishes. let's bring in our chief medical correspondent, sanjay gupta. they say, sanjay, it was a mild heart attack. what does all this say to you? a fifth heart attack has to be a serious issue. >> there's no question, any kind of heart attack is going to be a serious issue. what they looked at specifically, and it's interesting, if there is a concern about a heart attack, a certain muscle within the heart attack actually, some of the enzymes will be released into the blood, and that can actually be measured. so you can measure if someone had a heart attack and the